Effect of labetalol on continuous ambulatory blood pressure.

1 The hypotensive action of labetalol was evaluated during 24 h by continuous intra-arterial ambulatory monitoring in 14 patients. The dose used ranged from 300--1800 mg daily. 2 The drug caused a significant reduction of systolic BP in 19 and diastolic BP in 20 of the 24 h of monitoring. Heart rate was also reduced but less markedly than BP. 3 The rapid early morning increase in BP was also effectively controlled. 4 The mild pre-waking increase in BP was not significantly reduced. 5 Labetalol treatment reduced the variation in systolic BP from the lowest observed quarter-hourly mean as compared with pre-treatment values. 6 The quarter hourly mean values were consistently smooth and revealed no sudden variations which might have resulted from postural hypotension.


Monotherapy with labetalol for hypertensive patients with normal and impaired renal function.

1 Labetalol was given to 41 hypertensive patients in a divided dosage of 150--2,400 mg daily for periods ranging from 1--64 months. 2 Monotherapy with labetalol was adequate in 12 out of 19 patients with essential hypertension and in 15 out of the 22 with renal hypertension. 3 Following a single dose of labetalol 200 mg orally a hypotensive response was seen between 1.5 and 2 hours. 4 In the doses used there was no exercise or postural hypotension. 5 No reduction in overall renal function attributable to labetalol was seen.


Labetalol in severe and resistant hypertension.

1 The efficacy of labetalol in the treatment of severe hypertension (diastolic greater than or equal to 115 mm Hg) was studied retrospectively. Ten patients were followed for more than 6 months. At 6 months, eight were well controlled and the mean dose in those was 975 mg daily. Four of these were receiving labetalol alone; two were on labetalol and diuretic only. 2 Three patients were resistant to doses of 1600, 1800 and 2400 mg daily respectively; two of these were controlled with increased doses of vasodilator drugs. In two cases labetalol had produced large falls in the standing BP while not influencing the supine BP. 3 Three other resistant patients were seen, of whom one merely required an increase in dose to 2200 mg daily and the addition of a diuretic. Both the others were elderly, had severe vascular disease, and suffered disabling postural hypotension on a dose of labetalol which did not influence the supine BP. 4 Labetalol can control severe hypertension. There remain patients whose supine BP is not influenced by a dose of labetalol which produces marked postural hypotension.


Mean steady-state plasma concentrations of labetalol in patients undergoing antihypertensive therapy.

1 Mean steady-state plasma concentrations of labetalol (labetalol Css) in 17 hypertensive patients undergoing chronic treatment with this drug, have been examined in relation to dose, fall in BP, and beta-blockade. 2 A significant relationship (rs = 0.81, P less than 0.001) was observed between labetalol Css and daily dose. 3 No correlation was found between labetalol Css and antihypertensive response. 4 In thirteen patients, there seemed to be significant relationship between labetalol Css and beta-blockade (rs = 0.72, P less than 0.005). In three patients, the degree of beta-blockade was disproportionate to the drug concentration.


Pharmacokinetics and pharmacodynamic studies of labetalol in hypertensive subjects.

1 The pharmacokinetics of labetalol were studied in twelve hypertensive patients, ten of whom were not receiving other therapy. 2 Following intravenous administration there was a three- to fourfold variation in terminal elimination half-life, volume of distribution and total plasma clearance. The mean elimination half-life was 3.25 hours. 3 Following oral administration the drug was absorbed rapidly. Systemic availability varied from 11-86% (mean 33%). 4 Plasma levels correlated poorly with the acute effect on BP, raising the possibility of labetalol acting in a deep tissue compartment or alternatively an active metabolite contributing to its effect.


Long-term treatment of hypertension with labetalol.

1 Thirty-two hypertensive patients have been treated with labetalol for periods of up to 7 years. 2 Ten patients observed for 6 years from time of stabilization of dosage, did not show any tolerance to labetalol. 3 Postural and exercise hypotension were not seen in these patients over this prolonged follow-up, although they were seen in other patients given over 2 g labetalol daily.


A comparison and an investigation of a potential synergistic effect of labetalol and bethanidine in patients with mild hypertension.

1 The effects of labetalol, bethanidine and combined treatment with both drugs were compared in a within-patient randomized cross-over study in mild essential hypertension. Attention was directed to whether or not labetalol and bethanidine differed in their pattern of effect on arterial BP and whether evidence of synergism was apparent. 2 At the doses used labetalol significantly lowered systolic and diastolic BPs and heart rate lying, sitting, standing and after exercise. The dose of bethanidine used did not affect heart rate significantly while lowering systolic and diastolic BPs only after exercise and less clearly on standing. Combined treatment lowered BPs on standing and after exercise and heart rate after exercise. 3 The type and frequency of side-effects were similar with bethanidine and labetalol but were much less with combined treatment. 4 No evidence of synergism was observed.


Acute management of severe hypertension with oral labetalol.

1 Six previously untreated emergency admissions to hospital with severe hypertension were given oral treatment with labetalol. 2 Pre-treatment diastolic BP exceeded 130 mmHg, and clinical evidence of either accelerated hypertension or encephalopathy was present. 3 Hypotensive response after treatment followed two patterns. 4 Quick-responders (n = 3) showed a sharp fall in BP to normal levels within 2 h, which was subsequently sustained for 10 or more hours. The daily dose of labetalol eventually required to achieve good BP control in this group was relatively low: 600--1200 mg. 5 Slow-responders (n = 3) showed a gradual, less marked fall in BP, which was sustained for many hours. These patients required further doses of labetalol to reduce BP to normal. The eventual daily dose of labetalol that ensured good BP control was high: 1200--2400 mg. 6 Heart rate was little changed by treatment. 7 Complications or side-effects were not observed.


Comparison of effects on cerebral blood flow of rapid reduction in systemic arterial pressure by diazoxide and labetalol in hypertensive patients: preliminary findings.

1 Diazoxide 300 mg and labetalol 150 mg were each injected intravenously on separate occasions into five patients with essentail hypertension. The reduction in BP caused by labetalol was slightly greater than that produced by diazoxide. 2 In contrast the reduction in cerebral blood flow (CBF) by labetalol was not statistically significant, whereas diazoxide gave a greater and statistically significant reduction in CBF. 3 These observations suggest that labetalol may have an advantage over diazoxide for the rapid reduction in BP.


Open evaluation of labetalol in the treatment of angina pectoris occurring in hypertensive patients.

1 In nine hypertensive subjects with angina pectoris, labetalol diminished the incidence of chest pain occurring spontaneously or induced by exercise. 2 Labetalol lowered BP in all subjects. 3 Exercise tolerance at maximum levels was increased by labetalol. 4 Improved cardiac function by labetalol may be related to decreased afterload on the left ventricle, and diminished oxygen utilization by the myocardium.


Use of labetalol in the treatment of severe hypertension during pregnancy.

1 Labetalol, a hypotensive agent combining alpha- and beta-adrenoceptor antagonist properties, was used to treat severe hypertensive disease complicating pregnancy. 2 Effective reduction in BP was achieved in all but 3 of the 25 patients treated. Careful monitoring of feto-placental function was undertaken to ensure the maintenance of fetal well-being. Maternal and fetal side-effects were minimal and it was not necessary to discontinue the drug in any patient. 3 Labetalol was estimated in the cord blood of the fetus at delivery as well as in the breast milk of mothers on day 3 post partum. There were no adverse effects of the drug on the infants and significant hypotension did not occur. 4 The reults suggest that labetalol has a direct action on fetal lung maturation and this, together with its effective hypotensive effect, contributes to the low perinatal mortality (3.5%) observed. 5 Oculotoxicity due to the labetalol was not observed in the infants delivered. 6 It is concluded that the efficient hypotensive action of labetalol, together with apparent freedom from maternal and fetal side-effects, and consequent improved perinatal mortality, suggest that it is a suitable drug for use in pregnancy complicated by hypertension.


Use of labetalol and methyldopa in pregnancy-induced hypertension.

1 Nineteen pregnant patients whose mean arterial pressure (MAP) was persistently greater than or equal to 103.3 mmHg were given labetalol or methyldopa. 2 Singificant falls (P less than 0.001) in BP only occurred in the group treated with labetalol, and daily BP control was better in this group. 3 Two severely hypertensive patients were successfully treated with intravenous labetalol. 4 There was a higher incidence of spontaneous labour in the labetalol group and a significant difference (P less than 0.05) in the Bishop score of the cervix between the two groups. 5 There were no apparent detrimental effects on the foetus antenatally, during labour or post partum. 6 Slight breathlessness in one patient treated with labetalol was the only side-effect observed but drowsiness, headache and postural hypotension were reported in patients receiving methyldopa.


Use of labetalol during hypotensive anaesthesia and in the management of phaeochromocytoma.

1 The circulatory effects of labetalol have been studied in 88 patients undergoing plastic surgery, 8 patients with carcinoma of the breast, 10 with carcinoma in the head and neck, and in 2 patients with phaeochromocytoma, each anaesthetized twice. 2 The use of labetalol intravenously produced hypotension and a bloodless operating field in patients undergoing plastic surgery and in those undergoing radical surgery for the removal of carcinoma. 3 Two patients with phaeochromocytoma pre-treated with oral labetalol before anaesthesia, had well controlled BPs and heart rates during surgery, although in one instance additional intravenous labetalol was required. 4 Pre-operative preparation of patients with phaeochromocytoma with labetalol seems to be simpler and safer than previous techniques involving drugs with separate alpha- and beta-adrenoceptor-blocking effects.


Labetalol infusion in acute myocardial infarction with systemic hypertension.

1 Fifteen patients with suspected acute myocardial infarction and systemic BP of greater than 160/110 mmHg were treated with an incremental infusion of labetalol. 2 Systemic BPs were safely and effectively lowered to less than 130 mm Hg systolic or 90 mmHg diastolic in all pateints. 3 Heart rate, mean pulmonary artery wedge pressure cardiac index and stroke work index were significantly reduced. 4 The dose of labetalol varied from 30 mg--440 mg and was significantly higher (mean 295 mg) in those patients with pre-existing systemic hypertension compared with others (mean 133 mg). 5 No side-effects occurred and all patients survived to leave hospital.


Effect of labetalol in hypertension during exercise and postural changes.

1 Fourteen hypertensive patients were studied by intra-arterial BP monitoring to quantify the effects of standardized physiological stresses: Valsalva manoeuvre, isometric, treadmill and bicycle exercise, and 60 degree tilting before and after labetalol treatment. 2 The dose of labetalol ranged from 100--600 mg three times daily and the response was judged on outpatient clinic recordings. 3 The drug produced a sustained reduction of BP and heart rate responses during dynamic exercise and the Valsalva manoeuvre, but the degree of change from the lowered baseline were not changed by labetalol. The fall in BP on cessation of exercise was decreased rather than increased. 4 The response to controlled isometric muscle contraction was affected in a similar fashion. 5 Tilting produced a fall in BP after treatment, and this was most marked in those patients on the highest doses. However, compensatory increases in diastolic BP were observed.


Natural cytotoxic macrophages in the peritoneal cavity of mice.

Many strains of mice from various breeding institutes have natural cytotoxic macrophages. These macrophages can also be present in nude mice, suggesting that this cytotoxicity can be acquired without invovlvement of T cells. The natural cytotoxicity was non-specific for tumour cells, was not sensitive to trypsin treatment, was lost after 5 days incubation, but could be enhanced by foetal bovine serum. The presence of cytotoxic macrophages in the peritoneal cavity was not genetically or age controlled. Natural cytotoxic macrophages did not occur in germ-free mice. The possible causes of natural cytotoxicity are discussed.


Cell-cycle distribution of urothelial tumour cells as measured by flow cytometry.

The fraction of cells in S + G2 + mitosis from 54 urothelial tumours was calculated by flow cytometry after acridine orange (AO) staining of cells obtained by bladder irrigation or biopsy. Fluorescence signals emitted by the AO-stained DNA and RNA of each cell were separated optically and measured for 5,000 cells per specimen. The patients were classified by the histology of their tumours and clinical data into 5 diagnostic categories: NED (no evidence of disease, but history of bladder tumour), 3; papilloma, 8; non-invasive papillary carcinoma, 8; carcinoma in situ, 17 and invasive carcinoma, 18. The fraction of cells with DNA values in S + G2 + M of the cell cycle varied between 7 and 57% of the total, with a wide range within each diagnostic category, but no statistically significant differences between the groups. The proportion of cells in S + G2 + M from an individual tumour was not correlated with histologic grade or clinical behaviour. The possibility that some tumour cells with DNA values above G1 level are quiescent cells arrested at S or G2 is discussed.


Influence of hyperthermia on the oxygen enhancement ratio for x-rays, measured in vivo.

The skin of mouse tail has been used to study the effect of hyperthermia on the oxygen enhancement ratio (OER). Heating was by immersion of a portion of the tail in hot water. Radiation was given either immediately before or after hyperthermia. The average skin reaction between 15 and 50 days after treatment was taken as the end-point. The OER in the absence of hyperthermia was 1.77, suggesting significant hypoxia of the skin. When hyperthermia was given after irradiation the measured value for the OER was not significantly different, but with prior hyperthermia the OER was increased to an average value of 2.3. This increase in OER is probably due to a transient increase in blood circulation following hyperthermia and causing improved tissue oxygenation during irradiation. As a consequence we would expect a greater thermal enhancement ratio for heat given before irradiation than afterwards, and this has frequently been observed with other normal tissues. There was no evidence that heat reduces OER, as has been reported by some authors on the basis of experiments performed on cells in vitro.


The quantitative response of human tumours to radiation and misonidazole.

Eleven patients with measurable subcutaneous or pulmonary metastases were selected for a study of the effectiveness of the radiosensitizer misonidazole (MIS). Evaluable data were obtained in 6 patients and radiosensitization demonstrated in 5. Patients were irradiated either before or after MIS, and each patient acted as his own control. Response to treatment in 5 cases was assessed in terms of growth delay, and radiation doses were selected in expectation of enhancement ratios of 1.2 to 1.5. In 1 case evidence of sensitization was obtained from differential tumour clearance from 2 areas of skin irradiated before or after MIS. Results in 4/5 growth-delay studies indicated enhancement ratios ranging from 1.1 to greater than 1.5. An enhancement ratio of 1.3 was measured in a case of squamous carcinoma treated by a 10-fraction course of irradiation. Evidence of sensitization was obtained in breast carcinoma, osteosarcoma, leiomyosarcoma, prostatic carcinoma and synoviosarcoma. The results of this study support the view that MIS may improve the radiotherapeutic management of a wide range of tumours, although more extensive data are required to identify those categories of disease in which greatest benefit will be obtained, and to indicate the optimum radiation schedule.


Changes in NMR relaxation times of adjacent muscle after implantation of malignant and normal tissue.

In separate experiments, normal foreign tissue and malignant tumour were implanted s.c. into the rat thigh. NMR T1 values of the adjacent normal muscle, resulting from local inflammatory reactions or from malignant invasion, were measured. Elevations in T1 of the underlying muscle occurred within 24 h in both experiments, and it is believed these were caused by rapid inflammatory and immunological reactions to the implants. However the T1 values of muscle samples adjacent to the non-malignant implants decreased during the 11 days after implantation, dropping to values within the normal range. In the second experiment there was progressive malignant invasion into the normal adjacent tissue and the elevated T1 values were maintained throughout the 12-day period. The effects of the implantation on tissue water content are discussed in relation to NMR T1 relaxation times, and the relevance to whole-body NMR imaging of elevated T1 values due to nonmalignant pathological states is considered.


The carcinogenicity of 15,16-dihydro-11-methyl-cyclopenta[a]phenanthren-17-one.

Direct comparison of skin-tumour induction by 15,16-dihydro-11-methylcyclopenta[a]phenanthren-17-one (I) and by benzo[a]pyrene on mouse skin, both by repeated application or by initiation with a single dose followed by promotion with croton oil, demonstrated that these two carcinogens have similar potency. After repeated application of (I) the mean latent period for skin-tumour induction was linearly related to the logarithm of the dose over a 10-fold dose range. Under these conditions, application of the aryl-hydrocarbon-hydroxylase inhibitor 7,8-benzoflavone together with (I) inhibited tumour induction by about 40%. By contrast, in the 2-stage experiment, little effect on tumour incidence or latent period was observed when this inhibitor was applied with the single initiating dose of (I). Co-administration of the epoxide-hydratase inhibitor 1,1,1-trichloropropene oxide caused enhancement by shortening the latent period. After s.c. injection of (I) into mice, a similar number of tumours was induced on skin remote from the site of injection by promotion with corton oil begun either one week or 6 months after initiation. Gastric instillation of (I) into female rats induced mammary adenocarcinomas.


Carcinogenicity of betel quid ingredients: feeding mice with aqueous extract and the polyphenol fraction of betel nut.

Male mice of inbred strains Swiss and C17 were fed daily 5 times a week by intragastric tube 0.1 ml of betel-nut aqueous extract, betel-leaf aqueous extract and the polyphenol fraction of betel nut. Male mice of corresponding strains fed 0.1 ml of distilled water served as controls. Treated and control mice were kept under observation and killed when moribund. Betel-nut aqueous extract induced tumours of the gastrointestinal tract in 58% Swiss mice and 25% C17 mice. The polyphenol fraction by the same route induced tumours at other sites in 17% of the mice. Betel-leaf aqueous extract failed to induce any tumour in the treated mice, which supports an earlier report of the lack of any carcinogenic principle in betel leaf, an essential constituent of betel quid. Results are discussed in relation to the relevant literature.


Neutrophil marrow profiles in patients with rheumatoid arthritis and neutropenia.

Neutrophil marrow cellularity was determined in 14 neutropenic patients with rheumatoid arthritis (RA) from measurements of neutrophil-normoblast ratios in marrow biopsies and ferrokinetic estimates of marrow normoblasts. A marrow profile was developed for each patient comprising the numbers of promyelocytes and myelocytes, of metamyelocytes and bands, and of segmented neutrophils in whole marrow. In each case a maturation ratio was calculated by dividing the number of metamyelocytes and bands by the number of promyelocytes and myelocytes. The physiologic marrow response to loss of neutrophils from circulation was assumed to be an increase in promyelocytes and myelocytes due to proliferation and influx, a reduction in segmented cells due to early release, and a normal maturation ratio. The results were interpreted in the light of the 95% confidence limits for data previously obtained from 13 normal subjects: in patients with neutropenia reduced or basal numbers of promyelocytes and myelocytes were interpreted as absence of the anticipated proliferative response; increased numbers of marrow segmented cells were attributed to failure of release; a low maturation ratio was assessed to reflect intramedullary cell loss. The pattern in two patients with Felty's syndrome was consistent with a physiological response to neutrophil destruction. The other 12 patients had neutrophil marrow abnormalities. Seven patients with Felty's syndrome and four patients without splenomegaly had absolute or relative hypoplasia of neutrophil marrow or low maturation ratios. One patient with a normal spleen size had an increased number of marrow segmented cells yet failed to mobilize cells normally in response to dialysis coil-activation of C3. Abnormalities of neutrophil marrow may contribute to neutropenia in RA irrespective of the presence of splenomegaly. Recognition of neutrophil marrow abnormalities in these patients may be of value in prognosis and management.


A method for the investigation of reticuloendothelial iron kinetics in man.

A colloidal suspension of hydrolysed radio-iron of high specific activity has been developed for the investigation of reticuloendothelial (RE) iron kinetics in man. Following intravenous injection this material is cleared rapidly by the RE system and the iron released intn to the endogenous RE iron load, and it has proved possible to measure RE iron release without disturbing the normal iron flow.


Transplacental transport in the rabbit of vitamin B12 bound to human transcobalamin I, II and III.

Transcobalamins I, II and III (TCI, TCII, TCIII) were purified from human serum, saturated with 57Co-vitamin B12 (57Co-B12), and injected into pregnant rabbits. Whole body retention of the 57Co-B12 averaged 91% and was similar for each of the three vitamin B12 binders. A maximum of 62% of the injected 57Co-B12 was found in fetal tissues when the vitamin was injected bound to TCII, but only 6--7% when bound to TCI or TCIII. Thus TCII is responsible for the delivery of vitamin B12 to the fetus.


Mean cell volume in a working population: the effects of age, smoking, alcohol and oral contraception.

The effects of mean cell volume (MCV) of age, smoking habit, alcohol consumption, menopausal status, and use of oral contraceptives have been studied as appropriate in 1596 white men and 892 white women in working populations in North-West London. In men, increasing age, smoking and alcohol consumption each make an independent contribution to MCV. In women, the effect of smoking is similar to that in men; the effect of alcohol is less obvious, possibly because of the low stated alcohol intake in women. The effect of alcohol on MCV in the population studied is not as marked as in hospital patients who admit to excessive alcohol consumption; this may partly be due to differences in methods of eliciting intake. There is a small increase in MCV following the menopause. Women on oral contraceptives show a rise in MCV with increasing age; this is not seen in women not on oral contraceptives. There is a strong inverse association between MCV and red blood cell count, which may be part of a mechanism to ensure constant oxygen carrying capactiy.


Effect of fibrin degradation products and thrombin on fibrinogen synthesis.

The effect of intravenous administration of homologous fibrin degradation products and thrombin on fibrinogen synthesis was assessed in rabbits. The relative fibrinogen synthesis rate was calculated as a ratio of the amount of radiolabelled lysine incorporated into fibrinogen to the amount incorporated into albumin during the same measurement period. An increase in this ratio above control would indicate a relatively specific stimulation of fibrinogen synthesis as compared with albumin, which is not an acute-phase reactant. Injection of 45 mg of 'early' or 'late' fibrin degradation products failed to produce a significant increase in the relative fibrinogen synthesis rate, suggesting that fibrin degradation products play no feedback role in controlling fibrinogen synthesis. Infusion of small amounts of homologous thrombin (15--25 NIH u) was followed by a small but statistically significant elevation of the relative fibrinogen synthesis rate. This was not accompanied by any increase in the levels of fibrinogen degradation products in plasma, or by any decrease in plasma fibrinogen concentration, possibly suggesting that thrombin can stimulate fibrinogen synthesis by a mechanism independent of significant fibrinogenolysis or intravascular coagulation.


The chromatographic separation of factor VIII on aminohexyl sepharose.

A new method of factor VIII purification has been devised which involves chromatographic separation on aminohexyl-substituted agarose. Relatively large volumes of starting material can be processed compared to the volume of agarose employed and satisfactory yields are obtained. Factor-VIII-clotting activity is separated from the other related substances and resultant products appear to be stable. While separation of clotting activity occurs with relative ease, the antigen and ristocetin co-factor are hardly segregated, if at all. This provides a little more information about the interrelation of these substances. Results suggest that ion-exchange is involved in the mechanism of separation but additional hydrophobic or steric effects cannot be ruled out.


A study of cryosurgery for dysplasia and carcinoma in situ of the uterine cervix.

We studied 22 patients with a histopathological diagnosis of severe dysplasia and 89 patients with a diagnosis of carcinoma in situ of the uterine cervix. Twenty patients (18 per cent) had negative cervical smears for four to six years after diagnosis by biopsy of the cervix. The 91 patients with persistently abnormal smears were treated by cryosurgery, using a double freeze technique with nitrous oxide. Seventy-four (86 per cent) had persistently normal cervical smears after one treatment and eight after a second treatment while nine patients required conization for recurrently abnormal cervical smears. The duration of follow-up was five or six years in 48 patients (53 per cent). In a subsidiary study, material was obtained for histological examination from 72 patients with normal smears by endocervical curettage and multiple biopsies of the cervix; 8 showed slight atypia and 2 had residual carcinoma in situ.


An improved method of fetal weight estimation using ultrasound measurements of fetal abdominal circumference.

A simple and accurate method is described for estimating fetal weight from a single fetal abdomen circumference measurement at the level of the umbilical vein. The abdominal circumference was converted into a weight centile for the maturity at the time of measurement so that the weight at delivery could be predicted. This method was tested on a population of fetuses presenting by the breech near term. Although the error between actual and predicted weights was 194 g (1 SD) for all the patients, for a large well-defined subgroup the error was much smaller, being only 104 g (1 SD).


Intrapartum fetal monitoring with the cerebral function monitor.

We report a trial of the technical feasibility of monitoring the state of the fetal brain during labour using the Cerebral Function Monitor (CFM). This device was developed for long-term monitoring of the electroencephalogram (EEG). A tripolar scalp electrode allows removal of the fetal electrocardiograph (ECG) from the fetal EEG. Technically satisfactory recordings were obtained from 15 fetuses during labour for periods of up to 6 1/2 hours before delivery. There were alterations of CFM trace with fetal distress and also during general anesthesia for Caesarean section.


Measurement of fetal transcutaneous oxygen tension--problems and potential.

In a series of 39 fetuses, continuous intrapartum transcutaneous PO2 recordings were made using a commercially available skin electrode, applied to the shaven fetal scalp. The weak correlation between transcutaneous measurements and umbilical blood PO2 at delivery is believed to be due to scalp ischaemia produced by 'head to cervix' pressure during labour. This 'tonsure' effect presents a major obstacle to the use of surface electrodes for intrapartum blood gas monitoring from the fetal scalp in clinical obstetrics. Modification of the current technique may allow it to be used reliably for research.


Continuous measurement of transcutaneous fetal oxygen tension during labour.

Transcutaneous scalp oxygen tension (tcPO2) was measured during labour in 40 fetuses, using a modified Clark electrode (Radiometer, Copenhagen). In 24 of the fetuses the recordings were of good quality during the second stage of labour. After delivery the acid-base status and oxygenation of the umbilical cord blood was measured. A correlation was found between the tcPO2 and umbilical artery oxygen saturation (r = 0.56, p less than 0.01) and umbilical artery PO2 (r = 0.56, p less than 0.01). Furuthermore, a positive correlation was found between the area beneath the recorded tcPO2 curve during the last 10 minutes and the umbilical artery pH (r = 0.50, p less than 0.05). The data suggest that continuous transcutaneous PO2 measurement may be of value in monitoring high risk patients during labour.


Amniotic fluid palmitic acid/stearic acid ratios. Lecithin/sphingomyelin ratios and palmitic acid concentrations in the assessment of fetal lung maturity in diabetic pregnancies.

The lecithin/sphingomyelin (L/S) ratio, palmitic acid concentration and palmitic to stearic acid (P/S) ratio were estimated on samples of amniotic fluid obtained from 66 patients with diabetes. These were compared with similar estimates on amniotic fluid obtained from 127 non-diabetic patients. At 35 to 40 weeks, significant differences were observed between the L/S ratio and palmitic acid concentration in diabetics and non-diabetics, whereas the P/S ratio was similar in the two groups. The amniotic fluid L/S ratio, palmitic acid concentration, and P/S ratio were estimated on amniotic fluid obtained from 20 diabetic patients within 48 hours of induction, and the clinical outcome of the newborn infant was used to assess the predictive value of the three parameters. In 19 out of 20 diabetics the P/S ratio correctly predicted fetal lung maturity, whereas the palmitic acid concentration was correct in 12 patients and the L/S ratio in only 10 patients.


Mode of delivery and the lecithin/sphingomyelin ratio.

Babies born by elective Caesarean section are more likely to develop the respiratory distress syndrome that babies born vaginally. We studied the amniotic fluid and pharyngeal lecithin/sphingomyelin (L/S) ratios in three groups of babies born at term: 20 were delivered vaginally after elective induction of labour; 20 were delivered by elective Caesarean section; and 14 by Caesarean section after spontaneous onset of labour. Babies born after induction of labour had higher pharyngeal L/S ratios than babies born by elective Caesarean section. Those born by Caesarean section after spontaneous onset of labour had significantly higher pharyngeal L/S ratios than those in both of the elective delivery groups. There were no significant differences in the amniotic fluid L/S ratios of the two groups who underwent elective delivery. Regression analysis showed a significant relationship between length of labour and increase in the L/S ratio. These results indicate that, during labour, there is a release of fetal lung surfactant into the airways.


Epidural analgesia and placental blood flow during labour in pregnancies complicated by hypertension.

Placental blood flow was measured during the first stage of labour in pregnancies complicated by essential hypertension or severe pre-eclampsia using a 133Xe clearance technique before and after segmental epidural analgesia. Analgesia was produced with 0.5 per cent plain bupivacaine in six patients with essential hypertension and in 11 patients with severe pre-eclampsia. After segmental epidural analgesia the placental blood flow was slightly but insiginificantly improved in most of the patients with pre-eclampsia and in half of the patients with essential hypertension, thus suggesting this analgesic method to be safe in hypertensive pregnancies in the absence of any substantial change in systemic blood pressure.


Relation between the karyopyknotic index and plasma oestrogen concentrations after the menopause.

The karyopyknotic index correlated significantly (p less than 0.001) with the plasma oestradiol but not plasma oestrone concentration in 38 postmenopausal women. This ties with previous findings that postmenopausal women with superficial dyspareunia have a more severe degree of vaginal atrophy than asymptomatic women, and that oestradiol is probably more important biologically than oestrone.


Primary carcinoma of the fallopian tube associated with tuberculous salpingitis. A case report.

A patient with co-existent carcinoma and tuberculosis of the Fallopian tube is described. Tuberculosis was diagnosed by the finding of numerous typical granulomata throughout the uterus, tubes and ovaries, and by exclusion of other possible causes of these; and carcinoma by the finding of solid tumour, with a marked anisocytic appearance, invading submucosa. Despite the well recognised epithelial hyperplasia seen in tuberculous salpingitis, there remains no evidence that the occurrence of carcinoma in such cases is other than fortuitous.


Continual monitoring of intraocular pressure: effect of central venous pressure, respiration, and eye movements on continual recordings of intraocular pressure in the rabbit, dog, and man.

A new method has been devised for continual monitoring of intraocular pressure by radiotelemetry. The use of this instrument for monitoring intraocular pressure by a variety of ophthalmic conditions is described.


Retinal vein obstruction and intraocular pressure: abnormal postural response independent of facility of outflow.

Eleven patients with a central retinal vein obstruction and 18 with tributary vein obstruction were examined. The intraocular pressure of both eyes of each subject was measured while he was in the sitting position and again after he had been lying down for 15 minutes. Tonography was then carried out on both eyes. No correlation was found between the value of the coefficient of outflow and the magnitude of the rise in intraocular pressure occurring in any eye on the adoption of the supine position, and no correlation between the relative values of the coefficients of outflow in any pair of eyes and the occurrence of the obstruction in one eye rather than the other.


Intraocular pressure reduction in chronic simple glaucoma by continuous infusion of dilute pilocarpine solution.

Ten hospital outpatients with bilateral chronic simple glaucoma received a single drop of 2% pilocarpine to one eye and a continuous infusion of 0.1 % pilocarpine at a flow rate of 0.01 ml/min to the other eye (both solutions were at pH 7.2). On another occasion the treatments were reversed. Measurements of intraocular pressure (IOP) and pupil diameter were made at 30 min intervals for 2 hours. The continuous infusion of dilute solution was as effective as the single drop of more concentrated solution in reducing IOP and in constricting the pupil; the drop was somewhat faster in producing its effect.


Acute closed-angle glaucoma: an investigation into the effect of delay in treatment.

A retrospective study of 212 eyes with acute closed-angle glaucoma is reported. A peak incidence in the sixth decade was noted and an increased incidence in females confirmed statistically. A surprising and often marked delay occurred in the presentation of many patients for treatment, but visual outcome was not influenced by such delay. Despite good control of intraocular pressure, many of the eyes suffered visual loss from optic nerve damage, and the visual outcome was not related to the height of intraocular pressure at presentation. Damage to the visual system occurred very early in the disease, probably with the initial acute rise of intraocular pressure, and eyes appear to vary in their susceptibility to such an insult. It does not appear that earlier presentation of the patient with acute glaucoma would significantly improve the visual outcome in terms of visual acuity. The short critical time before damage occurs to the eyes suggests a role for preventive ophthalmology in the detection and surgery of eyes at risk with shallow anterior chambers and narrow angles before they develop acute closed-angle glaucoma.


Management of acute closed-angle glaucoma with miotics and timolol.

The hypotensive effect of intramuscular or intravenous acetazolamide with frequent instillation of 2% or 4% pilocarpine in polyvinyl alcohol, or with single drops of pilocarpine in polyvinyl alcohol or oily vehicles, and the hypotensive effect of topical timolol alone and together with pilocarpine was investigated in the treatment of acute closed-angle glaucoma in 75 patients (81 eyes). The results showed that there was no marked difference in the hypotensive effect whether pilocarpine was used frequently or in a single dose, in different concentrations, or in different vehicles after acetazolamide. Topical timolol alone was not effective enough to control the intraocular pressure in acute closed-angle glaucoma, but a good hypotensive effect was seen when topical timolol was followed by pilocarpine. It is concluded that 1 drop of pilocarpine 3 hours after intravenous or intramuscular acetazolamide or after topical timolol may be sufficient to terminate an acute attack. Topical timolol may serve as a valuable alternative when systemic medication is contraindicated.


Transient open-angle glaucoma associated with sickle cell trait: report of 4 cases.

Four black patients, all with sickle trait (SA), developed transient open-angle glaucoma with blood in Schlemm's canal. In 3 patients the condition followed blunt trauma, while in the fourth no antecedent trauma was described. The intraocular pressure became normal in all 4 cases with the resolution of the haemorrhage from the trabecular meshwork and Schlemm's canal.


Ocular findings in sickle cell-haemoglobin O Arab disease.

The ocular findings in 2 patients with sickle cell-haemoglobin O Arab disease are described. One patient had proliferative sickle cell retinopathy with extensive autoinfarction of lesions. Sickle cell-haemoglobin O Arab disease must be added to the list of conditions that may be associated with proliferative sickle cell retinopathy.


Ocular findings in a case of haemoglobin H disease.

A case is reported of a patient with known haemoglobin H disease who was found to have angioid streaks and retinal detachment. Angioid streaks have not previously been reported in cases of alpha-thalassaemia, and the question whether this is a chance association or otherwise is discussed.


Ocular involvement in scleroderma.

Thirty-eight patients with scleroderma (progressive systemic sclerosis) without renal failure were subjected to detailed clinical ophthalmic assessment. Abnormalities were frequent. However, many of these, including lens opacities, vitreous frosting, and arteriosclerotic changes, were considered to be age-related, and there were various incidental changes. Posterior subcapsular lens opacities in one patient were probably corticosteroid-induced. Changes related to scleroderma included eyelid abnormalities (stiffness or tightness in 11, telangiectasia in 8), deficient tear secretion (14 cases), and conjunctival abnormalities (injection 19 cases, vascular sludging 27 cases). Iris light reflux (6 cases) was possibly related to scleroderma. The changes related to scleroderma occurred in the 3 types classified according to the extent of skin involvement.


Diagnosis and management of a wooden orbital foreign body: case report.

The case history of a patient with a retained wooden orbital foreign body is presented. The report illustrates the diagnostic limitations of orbital CAT scanning and ultrasonography. Systemic corticosteroid therapy facilitated the localisation and surgical removal of the foreign body.


Phosphate transport and proteins with SH groups in rat liver mitochondria.

Phosphate transport in rat liver mitochondria was studied by following [32P] phosphate uptake within physiological concentrations. Transport inhibition due to mersalyl and protection by mersalyl against N-ethylmaleimide measured in those conditions corresponded to earlier results obtained by the swelling technique. When mitochondria were incubated with [3H] N-ethylmaleimide in the presence of mersalyl, the radioactive labeling in proteins of particles obtained after sonication was decreased in all fractions, but three proteins were both highly alkylated and also highly protected by mersalyl (M.W. 48,000 - 36,000 - 31,000). Two of these (M.W. 36,000 and 31,000) were partially purified by ultrogel chromatography in the presence of sodium dodecyl sulfate. Furthermore, it was shown that both phosphate and nigericin diminished labeling by N-ethylmaleimide in the final supernatant fraction. Two proteins (M.W. 98,000 and 31,000) were significantly alkylated by [3H] N-ethylmaleimide and protected by phosphate and nigericin.


Preferential incorporation of an exogenous cytokinin, N6-benzyladenine, into 18S and 25S ribosomal RNA of tobacco cells in suspension culture.

Cytokinin-requiring tobacco cells were incubated for 10 h in the presence of a labeled cytokinin. N6-benzyl-[2-3H]Ade, and of [8-14C]Ado. After alkaline hydrolysis of total RNA and fractionation of the resulting nucleotides, 80 per cent of the 3H radioactivity of RNA were recovered as the N6-benzyl-Ado nucleotide, covalently inserted into polynucleotidic chains. The N6-benzyl-Ado nucleotide was not significantly labled by 14C: at most one part of this nucleotide per 10 000 may result from a transfer of the benzyl moiety to adenyl residues in preformed RNA. Thus, the covalent insertion of N6-benzyl-Ade into RNA involves the intact N6-substituted base. Total RNA was fractionated either by sucrose density gradient centrifugation or by polyacrylamide gel electrophoresis. All identified RNA species were shown to contain N6-benzyl-Ade. The insertion frequency, measured as the molecular proportion of N6-benzyl-Ade to the total base content, was 3 to 4 times larger in 25S and 18S rRNA than in 5S and 4S RNA. The amount of N6-benzyl-Ade inserted into cytoplasmic ribosomal RNA accounted for about 90 per cent of the amount incorporated into total RNA. Electrophoresis of denatured RNA in the presence of formamide provided additional evidence that N6-benzyl-Ade was indeed incorporated into RNA molecules.


Demonstration of growth in porcine thyroid cell culture.

Eagle's minimum essential medium supplemented with 20 per cent newborn calf serum (N.C.S.) allows porcine thyroid cell survival but not cell growth in vitro. In NCTC 109 medium supplemented with 20 per cent N.C.S. these cells actively grow and may be serially propagated. Cell population doubling time expressed as DNA doubling value is 3.5 days at 37 degrees C in 95 per cent air-5 per cent CO2. Thyrotropin does not affect porcine thyroid cell multiplication in vitro but stimulates the plating efficiency in primary cultures to about 130 per cent of controls. Cell selection was obtained by replacing media with Earle's balanced salt solution. This operation provoked death of nearly all cells by day 18 but subsequent addition of growth medium resulted in proliferation of epithelial cell clones. From generation 2 to generation 8, cells produce thyroglobulin but they do not actively trap iodide nor form follicles when thyrotropin is added to the media. Cell selection, demonstration of growth, as well as freeze-storage techniques described in this paper permit selection and storage of porcine thyroid cells and the potential constitution of cell collections.


Effect of phosphate ions on the fluorescence of tryptophan derivatives. Implications in fluorescence investigation of protein-nucleic acid complexes.

In order to test the ability of phosphate groups to quench the fluorescence of tryptophan in protein-nucleic acid complexes we have studied the effect of various phosphate ions on the fluorescence of tryptophan derivatives. Unsubstituted and monoalkyl monoanions (H2PO4- and CH3OPO3H-) quench the fluorescence of all investigated indole derivatives while the dimethyl anion (CH3O)2 PO2- does not. This suggests that quenching of tryptophan fluorescence by phosphate monoanions requires the presence of an acidic OH group and could be due to a proton transfer from the phosphate ion to the indole chromophore. Trianions (PO4 3-4) which are strong proton acceptors quench the fluorescence of all tryptophan derivatives except N(1)methyl tryptophan. This result strongly supports our proposal that quenching of tryptophan fluorescence by phosphate trianions occurs through deprotonation of the NH indole group. Bianions (HPO '4(7), and CH3O PO3 2-3) quench the fluorescence of several indole derivatives including N-acetyl tryptophanamide but have no effect on tryptophan or N(1)-methyl tryptophan. From our results we conclude that phosphate groups of nucleic acids are not able to quench the fluorescence of tryptophyl residues in protein-nucleic acid complexes except if an accessible residue is located near a phosphorylated polynucleotide chain end.


Operant conditioning of EEG rhythms and ritalin in the treatment of hyperkinesis.

Enhanced voluntary motor inhibition regularly accompanies conditioned increases in the sensorimotor rhythm (SMR), a 12--14-Hz Rolandic EEG rhythm in cats.A similar rhythm, presumably SMR, has also been identified in the human EEG. The clinical effectiveness of SMR operant conditioning has been claimed for epilepsy, insomnia, and hyperkinesis concurrent with seizure disorders. The present report attempts to follow up and replicate preliminary findings that suggested the technique's successful application to hyperkinesis uncomplicated by a history of epilepsy. SMR was defined as 12--14-Hz EEG activity in the absence of high-voltage slow-wave activity between 4 and 7 Hz. Anticipated treatment effects were indexed by systematic behavioral assessments of undirected motor activity and short attention span in the classroom. EEG and behavioral indices were monitored in four hyperkinetic children under the following six conditions: (1) No Drug, (2) Drug Only, (3) Drug and SMR Training I, (4) Drug and SMR Reversal Training, (5) Drug and SMR Training II, (6) No Drug and SMR Training. All hyperkinetic subjects were maintained on a constant drug regimen throughout the phases employing chemotherapy. Contingent increases and decreases in SMR occurred in three of four training subjects and were associated with similar changes in classroom assessments of motor inactivity. Combining medication and SMR training resulted in substantial improvements that exceeded the effects of drugs alone and were sustained with SMR training after medication was withdrawn. In contrast, these physiological and behavioral changes were absent in one highly distractible subject who failed to acquire the SMR task. Finally, pretraining levels of SMR accurately reflected both the seve-ity of original motor deficits and the susceptibility of hyperkinetic subjects to both treatments. Although the procedure clearly reduced hyperkinetic behavior, a salient, specific therapeutic factor could not be identified due to the dual EEG contingency imposed combined with associated changes in EMG. Despite these and other qualifying factors, the findings suggested the prognostic and diagnostic value of the SMR in the disorder when overactivity rather than distractibility is the predominant behavioral deficit.


The frontal electromyographic adaptation response. A potential source of confounding.

Undergraduates were recruited to provide a descriptive analysis of the frontal electromyographic (EMG) adaptation response. Following placement of sensors, subjects were instructed to lie quietly for 15 minutes. Averaging data across subjects, a statistically significant adaptation response was produced in the direction of relaxation that required about 11 minutes to stabilize. The adaptation course varied greatly among subjects as a function of the initial EMG value. A criterion of stability was recommended that would individualize the adaptation period.


A simple method for improving the fidelity of blood pressure recording to reduce experimenter scoring error.

The problem of scoring blood pressure recording output produced via conventional polygraph equipment is discussed and illustrated, and a simple method for improving the fidelity of blood pressure output is detailed.


Successful treatment of one case of tardive dyskinesia with electromyographic feedback from the masseter muscle.

Evidence from one case with a 15-month follow-up is presented to support the conclusion that electromyographic (EMG) feedback from the masseter was effective in controlling tardive dyskinesia, while a combination of EMG feedback from the frontalis and verbal muscle relaxation training were not.


Transient persistence of neural activity after periodic stimulation in the cat LGN.

Oscillatory neural activity recorded from gross concentric electrodes implanted in the lateral geniculate nucleus (LGN) of cat was investigated after trains of periodic electrical shock stimulation were applied to the contralateral optic nerve. Spectral analysis using repeated trials and spectral averaging revealed statistically significant spectral peaks (p less than 0.05) at the stimulus frequency when there was a 0.5 to 1.5 s delay between the last pulse of the stimulus train and the beginning of the data analysis window. This suggests that a loosely coupled neuronal net may allow for the continuation of activity far longer than the time accounted for by neuronal time constants and delays.


An analysis of the peristaltic reflex.

A mathematical model describing the dynamics of the peristaltic reflex in an isolated intestinal segment is presented. The model is referred to a preparation that makes it possible to record the relevant mechanical and electrical variables during the course of the reflex. A simplified representation is used for the structure and the operation of the intrinsic nervous plexus, but the interaction between mechanical and elctrical events appears quite clearly and some features of the experimental data are well predicted.


Empirical examination of the threshold model of neuron firing.

An elementary model of neuronal activity involves temporal and spatial summation of postsynaptic currents that are elicited by presynaptic spikes and that, in turn, elicit postsynaptic potentials at a trigger zone; when the potential at the trigger zone exceeds a "threshold" level, a postsynaptic spike is generated. This paper describes three methods of estimating the "summation function", that is, the function of time that converts the synaptic current into potential at the trigger zone: namely, maximum likelihood, cross-correlation analysis and cross-spectral analysis. All three methods, when applied to input-output data collected on various neurons of Aplysia californica, give comparable results. As estimated, the summation function involved in the explored cells has an early positive-going swing that is large and brief. In the cell L5, but not in R2, there was also a late negative-going swing of longer duration.


EEG analysis gives model of neuronal template-matching mechanism for sensory search with olfactory bulb.

The spatial pattern of EEG activity at the surface of the olfactory bulb tends to be invariant with respect to input and to change to a new pattern whenever an animal is trained to expect or search for a particular odor. It is postulated here that the spatial EEG pattern is dependent on a neural template for that odor that is formed during training. This hypothesis is expressed in the form of a model consisting of an array of interconnected elements (1 X 10 or 6 X 6). Each element represents 2 excitatory and 2 inhibitory subsets of neurons with 3 types of internal feedback: negative, mutually excitatory, and mutually inhibitory. The elements are interconnected only by mutual excitation and mutual inhibition. Each neural subset is represented by a nonlinear differential equation; the connections are represented by modifiable coupling coefficients. With appropriate values of the time, coupling, and gain coefficients, and with input that is modelled on olfactory input, the set of 40 or 144 equations gives output that simulates the time and space patterns of the EEG. In the naive state the coefficients are uniform. A template is formed by giving input to selected elements, cross-correlating the outputs, and weighting the mutually excitatory coupling coefficient between each pair of elements by the corresponding correlation coefficient. When a template has been formed, input to nontemplate elements is treated as noise. Optionally a matched filter is made to simulate habituation by reducing the synaptic gain coefficients of those excitatory subsets that receive the noise. The model is tested by giving input to nontemplate elements and to none, part or all of the template elements. There are two outputs of the model. One is the spatial pattern Vj of the root mean square (rms) amplitudes of the individual outputs v(j, t) of the elements. The other output is the rms amplitude Erms of the ensemble average E(t) over v(j, t). The results show that Vj depends on the template and is relatively insensitive to input, whether or not input is given to template elements. However, Erms increases in proportion to the number of "hits" on the template. If the number of elements receiving noise does not exceed the number of elements in a template, or if the noise is matched with a habituation filter, then Erms rises above the noise level for a "hit" on any one or more template elements irrespective of location or combination. Vj conforms to the performance of the surface EEG. Erms is not yet accessible to physiological measurement.


The application of the Gierer-Meinhardt equations to the development of the retinotectal projection.

Model calculations are presented for the several properties of the development of the retinotectal projection in amphibians and fishes, using the Gierer-Meinhardt equations. One of these properties is the maintenance of topographic mapping between the retina and the tectum during their development despite the fact that the two tissues grow in morphologically different ways. Another is the existence of a "critical period", at which the coordinates of the retina with respect to the tectum are irrevocably determined. It is assumed that the connections between the retinal and the tectal cells are made on the correspondence of positional markers which are given as a form of the distribution of a specific activator, the dynamics of which is described by the Gierer-Meinhardt equations. The monotonic distributions of the activator and the existence of the critical period are shown by a computer simulation of the proliferating retina. Several changes of the retinotectal projection after surgical operations on the retina or the tectum are also explained.


A model describing nonlinearities in hearing by active processes with saturation at 40 dB.

Data from literature related to nonlinearities of the peripheral part of the hearing system are collected and extended by results from measurements of acoustical responses, masking, cubic difference tones and Zwicker tones. The data indicate 40 dB as a significant value for the dynamic range in neurophysiology as well as for the sensation level in psychoacoustics dividing the total level range into two areas of different characteristics. A preliminary model assuming that the outer hair cells act as an amplifier which contains saturation (corresponding to 40 dB) and feed back to sensitize the inner hair cells is used to describe the measured effects at least qualitatively.


Contents of trace elements in the human liver before birth.

A multielement analysis was carried out in nine fetal livers (age: 23 weeks of gestation to term) in comparison to an adult control group (n = 37). 15 elements (phosphorus to lead) were analyzed by proton-induced X-ray emission (PIXE). Significant differences between the two groups, expressed as ratios (R) of fetal to adult liver values were observed for copper (R = 16), zinc (R = 2.0), iron (R = 1.5), calcium (R = 1.34), selenium (R = 1.22), manganese (R = 0.7), and molybdenum (R = 0.13). An interesting point seems to be the inverse relation of copper and molybdenum. The negative correlation of these two trace elements which is known from animal experiments has now been confirmed in the human liver.


Postnatal development of cardiac distribution in the pig.

Distribution of cardiac output was measured in 0- and 12-hour-old piglets using 103Ruthenium-labelled microspheres, 15 +/- 3 micrometer in diameter. The 12-hour-old piglets had remained with the sow and had suckled. Coronary and bronchial fractions of cardiac output were high in piglets at birth. The coronary fraction remained high at 12 h but the bronchial fraction decreased significantly (p less than 0.05). Percent cardiac output to the liver and upper gastrointestinal tract, pancreas and salivery gland in 12-hour-old piglets was significantly increased (p less than 0.01) by 138, 156, 85 and 109%, respectively, compared with piglets at birth. Preferential blood flow occurred to the lungs, adrenals, heart, thyroid and spleen at 0 h and to the adrenals, thyroid, heart, lungs and diaphragm at 12 h.


Electrolyte composition of fetuses, placentas, and maternal plasma during the last trimester of gestation in the rat.

Pregnant rats were sacrificed during their last trimester of pregnancy. Maternal plasma levels of calcium and zinc decreased during gestation, whereas calcium and zinc levels increased in fetuses as gestation progressed. Although sodium and potassium levels remained relatively constant in maternal plasma, the levels of these electrolytes in fetuses decreased with gestation. Magnesium levels remained relatively unchanged in both maternal plasma and fetuses. The changes in placenta electrolyte content resembled the pattern of changes in fetuses.


Effects of anemia and growth retardation on respiratory activity in the piglet.

Respiratory activity (RA) was assessed in a piglet model by giving chloralose (Ch), 6 mg/kg i.v. every 2 min, until the appearance of apnea. The total cumulative dose of Ch (mg/kg) which produced permanent apnea (lethal dose, LD) was determined. The slope of the dose-respiratory frequency curve (R = ae-lambda Ch) was also computed. The LD of Ch increased progressively with age, while respiratory frequency (lambda) decreased. However, in piglets with severe spontaneous anemia (hematocrit less than 10%), the LD of Ch was less than half that expected for the age groups, and the rate of reduction of gamma was much greater. The enhanced sensitivity to inhibition of RA may relate in part to anemia with reduced O2-carrying capacity to the CNS, and in part to growth retardation with delayed respiratory center maturation.


Postnatal maturation of phrenic, vagus, and intercostal nerves in the kitten.

In the present work, we have compared the histological maturation of the phrenic nerve, the internal and external intercostal nerves of the 8th space and the vagus nerve. At least three nerves from each category have been taken from different kittens each week during the first 2 months of postnatal life, and each month for kittens aged between 2 and 8 months. Compared to references obtained in the adult animal, the development of the number and diameter of myelinated fibers has been studied for each nerve. Moreover, the maturation of unmyelinated fibers of the phrenic nerve has been studied with the electrom microscope. There is a possibility of a cephalo-caudal maturation in the somatic nerves. Important differences exist between somatic nerve maturation and that of the vagus nerve.


Saccharin- or quinine-induced changes in the rat pups following prolonged ingestion by the dam.

Effects presumably induced by a chronic free ingestion of saccharin (0.40 mg/ml) or of quinine (0.25 mg/ml) by female rats during the pregestative, gestative and lactating periods were investigated in the ensuing progeny. Preweaned pups were studied from birth up to weaning (21 days of age) by means of selected gross behavioral tests. The saccharin litters were mainly characterized by a slowering in the body growth evolution. The quinine pups demonstrate several physical anomalies: (1) congenital malformations in 5% of the animals; (2) a significantly reduced birth weight followed by a persistent growth retardation, and (3) a significant delay in the teeth eruption (1.6 and 2.6 days) and in the eye openings (1.6 days). In comparison to the untreated offspring, the saccharin pups showed minor effects whereas quinine-exposed rats were clearly impaired in several features of the postnatal physical development. Therefore, the addition of the sweetener to morphine solution may be convenient for the voluntary oral consumption of the narcotic. Conversely, quinine, used to habituate animals to drinking bitter solutions, has to be rejected in this narcotization procedure as being a harmful agent to the growing rat.


Urinary excretion of glomerular basement membrane antigens in premature infants and the newborn.

25 premature infants, 8 mature newborns and 25 children between 5 and 15 years of age were examined for urinary excretion of glomerular basement membrane (GBM) antigens. For the characterization of the excreted GBM antigen, immunoelectrophoresis was applied. In the group of 25 premature infants 23 showed alpha-1-mobility, in the group of 8 mature newborns all showed alpha-1-mobility, and in the group of the 25 children aged 5--15 years 24 showed migration into the alpha-2-zone. Differentiating, whether the difference between the immature and mature GBM is quantitative or qualitative, the immunoelectrophoretical difference points to the interpretation that the premature GMB shows a unique chemical composition.


Distribution of fluid between extracellular and intracellular compartments in the heart, lungs, liver and spleen of neonatal rats.

The volume of fluid in various tissue compartments of thoracic and abdominal viscera in neonatal rats has been calculated from the steady state distribution of radioindicators. During the first 3 weeks after birth, the volume of extracellular fluid (3H-inulin space) decreases at a similar rate (ca. 0.04 ml/g tissue/week) in heart, lungs, liver and spleen. Over the same postnatal period, the 51Cr tagged erythrocyte space (an estimate of vascularity) remains relatively constant in liver, increases slightly in the heart and spleen, and rises substantially (3-fold increase) in the lungs. The volume of parenchymal cell water, calculated from data for tissue water content and radioindicator spaces, tends to increase with age. However, the distribution of fluid between extracellular and intracellular compartments in 3-week-old animals is similar to that in adults.


Effect of progesterone treatment on the development and function of neonatal rat adrenals and testes.

The high progesterone (P) level of pregnancy was mimicked in neonatal male rats. The rats received 10, 30 or 100 microgram/g body weight of P in daily subcutaneous injections for 1, 2 or 3 weeks. It was expected that the treatment would yield developmental and functional changes similar to those possibly occurring under the influene of P in utero. P did not significantly affect the body weights of the animals, but significantly decreased the weights of the adrenals. Testicular weight was increased in the P-treated rats, and the number of Leydig cells was higher than in the controls. Peripheral serum testosterone and corticosterone, and testicular testosterone levels were only slightly decreased by the treatment. The changes observed in these neonatal animals suggest a regulatory function for P in the development of the fetal adrenal gland and testis.


Delta 9- and delta 6-desaturase activities of the ovine placenta and their role in the supply of fatty acids to the fetus.

Although the fatty acid compositions of the total  lipids of the sheep placenta and fetal plasma were shown to be broadly similar, they differed significantly from the fatty acid composition of the maternal plasma unesterified fatty acids, the plasma lipid component from which the fetus derives almost all of its requirements for pre-formed fatty acids. In particular, the placental and fetal plasma lipids displayed a 3-fold higher oleic acid/stearic acid ratio and contained a significantly higher proportion of arachidonic acid than the maternal unesterified fatty acids. These differences correlated well with the high delta 9- and delta 6-desaturase activities, respectively, shown to be present in sheep placental tissue in vitro. The levels of these enzymes in placental tissue contrasted with the relatively low desaturase activities found to be present in adult and neonatal sheep liver and in the placentas of other, non-ruminant, species. The possible role of such high levels of desaturase activity in the sheep placenta is discussed in relation to the particularly poor essential fatty acid status imposed upon the fetal ruminant.


Effects of maternal hypervitaminosis A on perinatal rat lung histology.

Retinyl acetate (160,000 USP/day in corn oil) was administered orally to pregnant Long-Evans rats during the last third of gestation. Postnatal evaluation of this treatment was assessed by examination of histologic sections of lung taken from stillborns and from pups that survived several hours. In all sections from treated litters, expansion of lung either did not appear to have occurred, or was not uniform. Control lung sections were uniformly expanded in all cases. It appears that hypervitaminosis A during the fetal period alters normal lung maturation. These data provide additional supporting evidence that the fetal period is susceptible to teratogens.


Quantitative measurement of body motion using Schottky barrier silicon photodiode.

A new motion detection system has been developed using a laser beam and a Schottky barrier silicon photodiode. The system broadens the scope of gravitational center stabilography by facilitating the quantitative assessment of tremors of body appendages such as the hands and even the head. The system also eliminates cumbersome platforms and wire attachments previously used in gravitational center stabilography. The subject is asked to aim the beam at the photodiode. A quantitative off-center variation parameter, ARDS (Average Radial Distance Squared multiplied by time), was utilized in units of cm2 sec. A preliminary evaluation of the system shows that it is suitable for rapidly screening large numbers of subjects for localised neuromuscular control.


Hospital equipment management, maintenance and quality control in the Netherlands.

Before 1970, equipment maintenance and quality control in Dutch hospitals were not organised. There was little or no cooperation between physicians, hospital employees and instrument suppliers. Health services which are not nationalised are funded by non-profit making foundations. There were few regulations covering the supply and maintenance of equipment. However, the country is small enough for there to be considerable contact between instrument engineers. In the past eight years a new situation has arisen where rules are being formulated based on collective experiences. A better understanding has to grow between physicians, nurses and engineers, of each others' needs and possibilities in relation to the use of instruments and the necessity of maintenance. To keep quality on an acceptable level, exaggeration in one direction or another has to be avoided.


Falls from hospital beds as a result of poor mattress design: a case history.

Investigation of a series of falls from hospital beds showed that the cause was the poor design of the particular mattresses. Interior sprung mattresses of this construction are unstable at their edges and are particularly hazardous when used with the modern, rigid base hospital bed.


A comparison of two methods for making statistical inferences on Nei's measure of genetic distance.

The delta and jackknife methods can be used to estimate Nei's measure of genetic distance and calculate confidence intervals for this estimate. Computer stimulations were used to study the bias and variance of each estimator and the accuracy of the corresponding approximate 95% confidence intervals. The simulations were conducted using 3 sets of data and several sample sizes. The results showed: (1) the jackknife reduced bias; (2) in 8 out of 9 cases the variance and mean square error of the jackknife estimator were less; (3) a second order jackknife reduced the bias the most but suffered a corresponding increase in variance; (4) both the first order jackknife and delta methods yielded intervals whose confidence levels were approximately equal but less than 95%.


Predictive probability early termination plans for phase II clinical trials.

A phase II clinical trial is designed to gather data to help decide whether an experimental treatment has sufficient effectiveness to justify further study. In a one-arm trial with dichotomous outcome, we wish to test a simple null hypothesis on the Bernoulli parameter against a one-sided alternative in a sample of N patients. It is advisable to have a rule to terminate the trial early when evidence accumulates that the treatment is ineffective. Predictive probabilities based on the binomial distribution and beta and uniform prior distributions for the binomial parameter are found to be useful as the basis of group sequential designs. Size, power and average sample size for these designs are discussed. A process for the specification of an early termination plan, advice on the quantification of prior beliefs, and illustrative examples are included.


Distribution-free regression analysis of grouped survival data.

Methods based on regression models for logarithmic hazard functions, Cox models, are given for analysis of grouped and censored survival data. By making an approximation it is possible to obtain explicitly a maximum likelihood function involving only the regression parameters. This likelihood function is a convenient analog to Cox's partial likelihood for ungrouped data. The method is applied to data from a toxicological experiment.


Methods for analyzing panel studies of acute health effects of air pollution.

New methods are presented for analyzing repeated binary health measurements of individuals exposed to varying levels of air pollution. The methods involve a separate logistic regression of response against environmental covariates for each individual. Parameters reflecting individual susceptibility to pollutants and weather are estimated using Cox's regression techniques (1970, 1972a). The individual parameters are combined to yield summary estimates of environmental effects. The approach does not require independence of successive health measurements. It is illustrated with data on asthma and air pollution in the Los Angeles area.


Optimal timing of multiple applications of pesticides with residual toxicity.

Optimal timing of pesticide applications depends upon many factors including pest population demography, crop susceptibility to damage, weather and the rate at which a pesticide loses its toxicity. An efficient numerical optimization procedure incorporating these factors is developed and applied to the control of the Egyptian alfalfa weevil [Hypera Brunneipennis (Boheman)]. The procedure differs from earlier approaches in that the state vector describes the schedule of previous pesticide applications. Population density and age structure are used indirectly in construction of an equation which estimates pest damage to the crop as a function of the state vector. This approach can be used to calculate optimal timing of multiple pesticide applications based on a more detailed population model than previously has been possible. Calculation of the optimal pesticide application schedule with 11 age classes and 28 decision periods required only 25 seconds of CPU time on an IBM 370/168 computer.


Designing and analyzing clinical trials which allow institutions to randomize patients to a subset of the treatments under study.

When patients have been randomized between different sets of treatments the treatment groups are not strictly comparable. However, if one can assume that biases which are introduced affect the outcome additively, then one can compare treatments across these institutional options. This is illustrated for dichotomous response data and censored survival data. We show how the sample size must be increased to allow for this analysis and how the randomization should be weighted to obtain the best power. These results have application to simultaneous trials by different cooperative groups which have one or more common treatment arms.


A useful method for the analysis of growth studies.

A group of parsimonious models for the analysis of animal growth curves is presented. The effects of correlations between the successive weights are reduced by analyzing the weight gained between the different weighing times. A model is developed for the resulting two-way table of group average gain curves (group by periods), using the two-way table modeling techniques proposed by Mandel. The coefficients in the fitted model are examined to determine what functions of the weight gain measurements will summarize the characteristics of the curves. In the second part of the analysis these statistics are computed for each animal and analyzed to determine the effects of the design variables on the growth of the animals. Experience has shown that in many instances total weight gain summarizes all the information in the curve. The conditions under which total gain provides an adequate summary are discussed. The model has been used in the analysis of rat, dog, hamster, guinea pig and swine growth curves. An example is included to illustrate the utility of the proposed approach.


Immune reactions with cytotoxic activity to "self" in natural surveillance of aberrant cells.

Cytotoxic autoreactive lymphoid cells have been demonstrated to be a normal immunologic component in both normal and tumor-bearing organisms. The cells have a high antineoplastic potential. They are cytotoxic in vitro to non-immunogenic tumor cells, and a high in vivo activity of such cells may be positively correlated to in vivo regression of tumors. It is suggested that the cytotoxic activity of cytotoxic autoreactive cells reflects a natural mechanism to removal of all types of aberrant cells of which malignant cells are only a subset. It is further deduced that such mechanisms must be independent of cell surface neoantigens, and that cytotoxic autoreactive mechanisms with high probability therefore also are efficient against spontaneous malignant tumors.


Studies on the methodology and evaluation of the lymphocyte transformation microtest.

Optimum experimental conditions for the lymphocyte transformation microtest in healthy persons are described. The dependence of PHA stimulation on duration of culture, additions of serum and PHA concentration is investigated. A function of normal distribution pattern can be set up by determining the lymphocyte stimulability with four different PHA concentrations in the optimal stimulation range. With this function, the area under the curve, steepness, position and height of the maximum can be calculated. These parameters should serve for better interpretation of cellular immunity.


In vitro granulopoiesis in oligoblastic leukaemia: prognostic value, characterization and serial cloning of bone marrow colony and cluster forming cells in agar culture.

The colony and cluster forming capacity of bone marrow cells (BM CFC and CluFC) in agar culture, was studied from 20 oligoblastic patients. 13 patients had a leukemic growth pattern and 12 of these died within one year after diagnosis. 7 patients had no leukemic growth and 4 are alive 16 to 90 months after diagnosis. Both the determination of the proportion of abnormally light buoyant density of CFC and CluFC and the study of their suiciding index were used to characterize more precisely the leukemic or nonleukemic status of patients. Because of the small number of patients involved in the later preliminary study, the prognostic significance cannot be valuated. Serial studies of individual patients showed different types of evolution in the growth pattern of BM CFC and CluFC. Either the increase of BM CFC and CluFC paralleled that of the myeloblasts, or there was a change in the growth pattern before AML transformation suggesting clonal evolution.


Enrichment of murine granulomonocytic progenitors using a continuous linear Ficoll-Isopaque gradient.

Murine bone marrow was fractionated using a Ficoll-Isopaque continuous linear gradient characterized by an osmolarity of 290 mOsm constant throughout the gradient and a physiological pH of 7.4. The cellular peak detected prior to fractionation by means of a 405 nm light beam served as a guide for determining fraction collection. Under these conditions CFC enrichment was observed constantly for densities lower than that of the cellular peak. In 17 experiments the enrichment factor amounted to 3.6 +/- 1.4. Enrichment appeared to be due to both an increase in CFC concentration and an improvement in CFC cloning efficiency. A correlation between the concentration of CFC and that of undifferentiated blasts was observed. The CFC density distribution was dependent on the cell load. For cell loads lower than 25 x 10(6) the modal density of CFC was within the range 1.0615-1.0715. For cell loads higher than 25 x 10(6) there was a shift of the distribution curve towards higher density. Clu-CFC appeared to be denser than CFC. This increase in density may be due to a maturation process from CFC to Clu-FC as a maturation gradient with increasing density was found for the granulocytic series and for erythroblasts.


Study of platelet membrane proteins through fluorescence polarization of diphenyl hexatriene.

Fluorescence polarization (FP) of diphenylhexatriene (DPH) has been currently interpreted as cell membrane fluidity. We studied here FP of DPH labelled platelets under activation of membrane enzymes and concluded that FP of DPH could rather reveal interactions with hydrophobic pockets of membrane proteins.


Comparison of plasma deoxyribonuclease activity between normal and leukemic states in man and mice.

Plasma deoxyribonuclease (E.C.3.1.4.5.) activity was measured in patients suffering from acute non-lymphoblastic leukemia, in blastic phase and in remission, and in DBA2 mice, normal and bearing L1210 leukemia. No difference in enzymic activity could be observed between normal and leukemic states in human beings and mice.


Increased severity of the acute renal failure induced by HgCl2 on rats with reduced renal mass.

In rats unilaterally nephrectomized 2 days before and sham operated controls, an acute fenal failure (ARF) has been induced by subcutaneous HgCl2 injection. The uninephrectomized animals showed a more severe ARF than the sham operated, 60% of the former and 10% of the controls became anuric 48 hours after ARF induction. The increased diuresis and natriuresis produced by acute saline overload did not improve the severity of the ARF. The marked difference in the evolution of this model of ARF with respect to the glycerol induced ARF, which is ameliorated by reduction of renal mass, emphasizes the different pathogenetic mechanism of these two experimental models.


Effect of levamisole on interferon production by PHA-stimulated human leukocyte cultures.

Mononuclear leukocytes of 10 normal blood donors were cultured in vitro and treated with phytohemagglutinin (PHA-P) and/or levamisole. Interferon-like activity was investigated in the supernatant fluids of the cultures, using VSV as challenge virus. In most of the cases the PHA-stimulated interferon-like activity was slightly but significantly enhanced by levamisole. The antiviral activity produced in the supernatant fluids was characterized as interferon since it was trypsin sensitive, species specific and inhibited by specific antiserum. This interferon has the characteristic sensitivity to PH2 of immune interferon.


Hepatocarcinogenesis by aflatoxin B1: relationships between the cellular localization of the carcinogen and early histological changes in the rat liver.

Aflatoxin B1 (and/or its fluorescent metabolites) was identified by fluorescence microscopy in the liver of rats fed with this carcinogen. The timing of appearance of the carcinogen in the cytoplasm and nuclei of hepatocytes is analysed in relation to the various early histological changes observed in the liver.


Prostaglandins in human breast cancer. Identification of a cytosolic prostaglandin-9-keto-reductase activity.

Endogenous sources of prostaglandin production in human breast tumors were investigated by radioimmunoassay analysis of PGE2 and PGF2a productions and 3H-PGE2 conversion. PG synthetase located within the microsomal fraction mainly produced PGE2, while little PGF2a synthesis occured. In cytosol preparations. PGE2 is converted into PGF2a. In 15 tumor specimens, no relationship was observed between PGE2 production and the metabolic activity which varied widely from sample to sample. These findings demonstrate the presence of PG-9-keto-reductase in the cytosol from human breast tumors. A way of PGE2 inactivation by this enzyme is suggested since no less polar PGE2 metabolites were detected. It is concluded that PGE2 production by the microsomes will reflect the PG synthetase activity of a given human mammary carcinoma while metabolic conversion of PGE2 within the cytosol reflects the metabolic activity of the same sample. Both activities were otherwise apparently unlinked.


Inducibility of microsomal enzymes in normal and pre-cancerous lung tissue. Synergistic action of 5-6 benzoflavon or methyl-cholanthrene in radiation induced carcinogenesis.

The inducibility of pulmonary microsomal enzymes and the biological effects of chronic induction by 5-6 benzoflavone and methylcholanthrene were compared in normal and precancerous rats. Two important points were shown out: a dose of 6000 WLM resulted in a permanent modification of the pulmonary microsomal enzymatic pool and 5-6 benzoflavon was a strong co-factor of radiation induced carcinogenesis. This synergistic action was demonstrated by a much shorter latency, moreover neo-formed tissue and epidermoid cancers with a particular morphology were observed. In all the cases cancers appeared within 100 days following the beginning of the chemical treatment.


Cortisol secretion following nomifensine administration in normal subjects.

The effects of the oral administration of nomifensine, which inhibits endogenous cathecolamine re-uptake, on secretion of prolactin and cortisol were investigated in 12 normal subjects. In all the volunteers, a significant decrease of prolactin levels was observed following nomifensine administration. Cortisol levels were unaffected by this pharmacological treatment. The role of hypothalamic dopaminergic inhibitory system on ACTH-cortisol axis is discussed.


Effect of quinidine on mitogen-induced human lymphocyte transformation.

The effect of quinidine on mitogen-induced lymphocyte transformation was examined using a microculture technique. The results showed that, at concentrations attainable during therapy, this drug exerted an inhibitory effect on lymphocyte proliferation. This inhibitory effect could be partially reversed by washing. The inhibitory effect was quite substantial when the drug was added 48 hours after the initiation of cultures. The clinical implications of this immunosuppressive property of quinidine are discussed.


Simultaneous microscopic and biochemical findings in breast carcinoma. Preliminary results.

Intratumoral protein and glucose phosphate isomerase (GPI) content as well as median nuclear DNA amount were determined in breast carcinoma that could be classified by Bloom's grading. These data were analyzed in comparison with TNM classification. Higher protein contents have been displayed in T2 or N+ breast cancers than in T1 or N- tumors. Bloom's grading is strongly correlated to median nuclear DNA content and to some extent with protein and GPI amount. With these results, we have to think about the value of prognostic cytologic criteria. The relationship between intratumoral protein content and prognostic clinical or histological data requires our attention. This would seem to dictate a need for caution in expressing the results of some variables in function of protein content.


Proliferative effect of lithocholic acid on rat liver cell in culture.

In contrast to cholic acid, deoxycholic acid and chenodeoxycholic acid, lithocholic acid (LCA) enhances the growth of rat liver cells in culture. Enhanced proliferation of LCA-treated rat liver cells persists even 12 days after LCA was removed. These findings could suggest a mutagenic effect of LCA, or a metabolite, on rat liver cells.


Cardenolide analogues: 10--characterization of cardiac glycosides by chemical ionization mass spectrometry.

The potential of chemical ionization mass spectrometry for the characterization of naturally occurring and semi-synthetic cardiac glycosides has been investigated. Methane, isobutane and ammonia were used as reactant gases. With the exception of ouabain, the ammonia chemical ionization mass spectra of the cardiac glycosides examined in this work contained abundant [M + NH4]+ions and abundant fragment ions formed by cleavage of glycoside bonds. Ammonia chemical ionization mass spectrometry was found to provide a rapid and sensitive method for the characterization of the products of glycosidation reactions. In contrast, the methane and isobutane chemical ionization mass spectra of the cardiac glycosides, with the exception of ouabain, did not contain protonated molecular ions and did not contain abundant fragment ions above m/z 400.


A chemical ionization selected ion monitoring assay for methylphenidate and ritalinic acid.

A methane chemical ionization quantitative assay for methylphenidate and its major metabolite, ritalinic acid, is described. Methylphenidate and the internal standard, ethylphenidate, were extracted from plasma samples and derivatized to prevent thermal decomposition in the gas chromatography. Ritalinic acid was esterified with diazomethane and extracted as methylphenidate. The intensity of the protonated molecular ion of the derivatized drug and internal standard was measured by selected ion monitoring. Calibration curves were prepared from drug standards dissolved in drug-free plasma, and the lower limit of the curves extended to 0.5 ng methylphenidate per ml plasma. The method was used to generate plasma decay curves for pediatric patients undergoing methylphenidate therapy.


A gas chromatographic mass spectrometric chemical ionization assay for haloperidol with selected ion monitoring.

A new gas chromatographic mass spectrometric chemical ionization assay for haloperidol with selectedion monitoring is presented which provides for better combined selectivity and sensitivity than previous assays. Levels of haloperidol in 2 ml of human plasma were reproducibly measured down to subnanogram levels. Both methane and methane--ammonia chemical ionization spectra are presented for haloperidol and the internal standard trifluperidol.


A simple, rapid selected ion monitoring method for the determination of prostaglandins E2 and F2 alpha in human urine.

A new procedure for the simultaneous measurement of prostaglandins E2 and F2 alpha in human urine is described. Quantification was achieved by gas chromatography mass spectrometry with selected ion monitoring and deuterium labeled internal standards. The levels of measured prostaglandins ranged from 25 pg ml-1 of urine (PGE2) to 2500 pg ml-1 (PGF2 alhpa). The interassay coefficient of variation, determined by replicate analysis of four identical samples, was 1.9% for PGE2 and 0.8% for PGE2 alpha. The procedure takes a fraction of the time needed with published methods and can be conducted with as little as one-tenth of the daily urinary output.


Selected ion monitoring assay for the antidepressant maprotiline.

A procedure is described which permits the determination of maprotiline in biological fluids at concentrations ranging from 0.5 to 150 ng ml-1. It relies on the use of N-desmethylclomipramine or isotope labeled maprotiline as the internal standard, on derivatization of the secondary amines with heptafluorobutyric anhydride, and on the combined use of gas chromatography with chemical ionization mass spectrometry and computerized data handling. The assaying procedure is specific, accurate and precise. It is suitable for routine analyses and has sufficient sensitivity to permit monitoring the human blood levels expected from a single therapeutic dose for a week or longer. The method, which can monitor simultaneously isotope labeled and unlabeled maprotiline, can be used to great advantage for reducing variability problems encountered in bioavailability studies.


N-acylglycines: gas chromatographic mass spectrometric identification and determination in urine by selected ion monitoring.

Eleven biologically interesting N-acylglycines have been synthesized and the gas chromatographic and mass spectrometric properties of their trimethylsilyl derivatives studied, A sharp and reproducible gas chromatographic peak could be obtained for each N-acylglycine as the N, O-bis-(trimethylsilyl)-N-acylglycine. By the use of these derivatives a sensitive and specific selected ion monitoring method for the determination of N-acylglycines in human urine has been developed.


Mass spectrometry in the elucidation of shikimate biotransformation products in the rat.

The biotransformation products of shikimate in the rat have been identified by electron impact mass spectrometry. Analysis of the metabolites produced after oral administration of shikimate resulted in the identification of hippurate, 3,4,5,6-tetrahydrohippurate, hexahydrohippurate, benzoyl and cyclohexylcarbonyl-beta-D-glucuronides and two isomeric 3,4-dihydroxycyclohexanecarboxylates. Results showed that shikimate itself is not metabolized by rat tissues and that all metabolites produced were dependent upon initial metabolic transformations by gastrointestinal microrganisms. The various hippurate derivatives and glucuronide conjugates appear to arise via a conversion of shikimate to cyclohexanecarboxylate, which is then further metabolized by the rat tissues.


Abnormal deoxyribose metabolites in the urine of a child with a possible new inborn error of metabolism.

The urinary extract of a child investigated because of strabismus was found to contain large amounts of a compound which was identified using gas chromatography/mass spectrometry as 2-deoxyerythropentono-1,4-lactone. This lactone has not been observed previously in urinary extracts. When ion-exchange chromatography was used to isolate the organic acids from urine, the major peaks obtained by gas chromatography were shown to be 2-deoxyerythropentonic acid, 2-deoxyerythropentono-1,5-lactone and 2-deoxyerythropentono-1,4,lactone. Another abnormal metabolite, 2-deoxyribitol, was also excreted by the patient although this compound could not be detected in the urine of normal children. It is proposed that these unusual compounds accumulate in the urine of this child as a result of a defect in the catabolism of 2-deoxyribose.


The determination of terbutaline in human plasma by selected ion monitoring of the t-butyldimethylsilyl ether.

A method is described for the quantitative determination of terbutaline in 2 ml human plasma. The drug is extracted from plasma as the terbutaline tetraphenylboron ion pair and determined by gas chromatography mass spectrometry of its t-butyldimethylsily ether. Salbutamol is used as internal standard. Quantification is achieved by selected ion monitoring of the ion m/z 482 derived from t-butyldimethylsilyl terbutaline and m/z 495 from t-butyldimethylsilyl salbutamol. The detection limit was estimated to be 250 pg terbutaline ml-1 plasma. The coefficient of variation at the level of 1 ng terbutaline ml-1 was 4.1% (n = 5).


Remote group derivatives: limitations on the effectiveness of pyrrolidide derivatives of oxygen-containing fatty acids.

The pyrrolidides of a number of fatty acids containing oxygen functions (ether linkage, epoxide ring and hydroxyl group) have been prepared and their mass spectra recorded. Detailed analyses of these, supported by accurate mass measurement, indicate that the presence of the oxygen atom has a profound effect on the normal, sequential, mode of pyrrolidide fragmentation. Cleavage adjacent to the oxygen is enhanced, this being most marked in the spectra of those compounds containing an ether linkage. However, further fragmentation of the carbon chain distal to the pyrrolidide group is minimal and prevents any structural information being obtained. These findings indicate that the usefulness of the pyrrolidide derivative for structural elucidation purposes is severely limited in some cases when an oxygen atom is present in the chain. However, for both the epoxy- and hydroxy-fatty acids, complementary derivatization methods are available.


Identification and quantitation of urinary dicarboxylic acids as their dicyclohexyl esters in disease states by gas chromatography mass spectrometry.

Clinical studies were conducted by gas chromatography mass spectrometry selected ion monitoring of urinary dicarboxylic acids as dicyclohexyl esters. The dicyclohexyl esters of the dicarboxylic acids give characteristic electron impact mass spectra suitable for selected ion monitoring. The mass spectra exhibit a prominent acid + 1H ion and an (acid + 1H)-H2O ion for use as quantitating and confirming ions. The cyclohexyl esters are stable for days at room temperature and have excellent chromatographic properties. Dicarboxylic acid quantitation is performed within one hour using only 50 microliter of unpurified urine. A rapid method specifically for methylmalonic acid quantitation is described which has assisted physicians in the diagnosis of pernicious anemia and methylmalonic aciduria. This procedure is applicable for screening urinary organic acids for detection of inborn errors of metabolism. The detection of a child with elevated medium length dicarboxylic acids in the terminal urine specimen is reported. This condition, previously described as an inborn error, is attributed to a terminal event. Finally, an increase in urinary succinic acid paralleling putrescine levels is described during a response to cancer chemotherapy.


Mass spectra of alpha-amino acid oxazolidinones.

2-Bis-(chlorodifluoromethyl)-4-substituted-1,3-oxazolidin-5-ones, a new type of alpha-amino acid derivative for gas chromatographic separation, have been studied by low resolution mass spectrometry. These derivatives are obtained by reacting alpha-amino acids with dichlorotetrafluoroacetone. Their structure has been established or confirmed for most protein amino acids and several non-protein alpha-amino acids. The mechanisms responsible for the mass spectral pattern have been rationalized. An interesting feature of this derivatization procedure is that it distinguishes aspartic and glutamic acid from the respective amides. The structure of asparagine and glutamine derivatives has been established. A survey of oxazolidinone mass spectra has provided a list of diagnostically useful ions. Each amino acid can be identified by one or two of its most abundant fragments.


Analysis of tyrosine and deuterium labelled tyrosine in tissues and body fluids.

A gas chromatographic mass spectrometric method has been developed to determine tyrosine and deuterium labelled tyrosine in biological samples using alpha-methyltyrosine (alpha-Me Ty) or m-hydroxyphenylalanine as internal standards. With the latter standard both labelled and unlabelled tyrosine as well as alpha-Me Ty can be determined simultaneously, in for example human blood, following administration of alpha-Me Ty to inhibit catecholamine synthesis. After isolation of the amino acids on an ion exchange column (Amberlite IR 120) the butyl ester pentafluoropropionyl derivatives were prepared. In human plasma the precision of the method was determined at a level of 80 nmol tyrosine ml-1 and found to be +/- 5% (coefficient of variation, n = 10).