[The study of biological monitoring index for human exposed to BaP]. This paper studied the relationships among urinary BaP, Plasma BaP and SCE in rats and also analysed humans date. The results of animal experiments showed urinary BaP concentration were significantly correlated with BaP in plasma (r = 0.814, P < 0.01) and with the difference of the SCE frequency before and after BaP administration (r = 0.934, P < 0.01). The analytical results of humans data showed similar linear relationship between urinary BaP concentration and the level of exposure to BaP (r = 0.987, P < 0.0005), and also showed a positive correlation between the concentration of urinary BaP and the SCE frequency (r = 0.733, P < 0.05). We suggest the use of urinary BaP analysis as a biological monitoring index for exposure to BaP.


[Stroke, coronary heart disease and all cause mortalities analyses for hypertension]. The mortalities of 870 hypertensives, aged 35 and over, during 1986-1988 in a community were analysed, and SMRs (standardised mortality ratio) were calculated according to the data of population and mortality in the community. The results showed that, among the hypertensives, all cause death and stroke death were related to the level of systolic blood pressure beside the age. SMR analyses indicated that stroke death level in the group with hypertension was significantly higher than general population, and the extra death for all cause death, stroke and CHD (coronary heart disease) in the hypertensive group of less than 60 years old were particularly higher. However the SMR in the group of 70 or over were close to 100 or even lower than 100. It suggested that more consideration should be given to the hypertensives of younger age group (less than 60).


[Toxicity of chongqing acid fogwater on rabbit alveolar macrophages in vitro]. We collected acid fogwater on a fogday and observed its toxic effects on rabbits' pulmonary alveolar macrophages (AM) in vitro. The fogwater was diluted into 4 concentrations: 1, 1/10, 1/100, and 1/1000 of the original fogwater and the exposure time was 12 hours. The results showed that both the AM's viability and the phagocytic capacity were depressed significantly, but the AM's lysosomal enzyme--acid phosphatase activity was found to be stimulated to increase. All these changes were directly correlated with the degree of pollution of the fogwater. Of these three toxicity indices, the most sensitive one was the change of AM's phagocytic capacity.


[Effects of harman and norharman on aflatoxin B1 and aminopyrine metabolism by phenobarbital and 3-methylcholanthrene-induced rat liver microsomes]. Harman and norharman are two beta-carboline derivatives known to be present in certain foods and are formed during pyrolysis of amino-acids. Their effects on the metabolism of aflatoxin B1 and aminopyrine by 3-methylcholanthrene and phenobarbital-induced rat liver microsomes were studied. Both harman and norharman markedly inhibited the metabolism of aflatoxin B1 to its hydroxylated derivative, aflatoxin M1. However, only norharman showed an inhibitory effect on aminopyrine N-demethylation; harman had no effect. Harman and norharman inhibited aflatoxin B1 binding to DNA, mediated by hepatic microsomes in vitro.


[Investigations on ragweed pollens in the air in Qingdao District and its allergenicity]. A survey of the distribution of ragweed in Qingdao district was carried out. Ambrosia-artemisifolia has been found to be widespread in many areas. The results of the survey showed that ragweed pollen was the chief allergen of the district and that it was 18%-21.3% of total air-borne pollen in a year. Skin tests with Ambrosia allergen extracts showed a positive rate of 67.7% in 624 cases of pollinosis. Ragweed pollens have become the major allergic pollen, causing important pathogenesis with pollinosis in the district. Preventive measures must be taken to eradicate ragweed. Otherwise it certainly will spread all over China.


[Study on the pathogenic factors of pneumoconiosis in Beijing coal district]. Ferruginous bodies were first found in the lung tissues of coal miner autopsies in Beijing Coal mining. District irrespective of the presence or not pneumoconiosis, ferruginous bodies were found in the lung tissues as examined with two methods, tissue section and digestion and there was significance difference in their number. Two kinds of ferruginous bodies, one a "coal body", the other an "amphibole body" were distinguished when examined by EDXA. The fibrous particles in the dust extracted from the lung tissue are the physical basis of ferruginous bodies formation. After the lung dust has been subjected to X-ray diffraction analysis, there are also amphibole bodies in the lung tissue. There is no doubt that the presence of asbestos in the coal mine is one of the pathogenic factors of pneumoconiosis.


[Studies on metabolism of fungicide benzoic acid, 1,3-dithiolan-2-ylidenehydrazide in vitro]. The metabolism of fungicide benzoic acid, 1,3-dithiolan-2-ylidenehydrazied (Yekuling) was studied quantitatively in rat liver microsomes and liver soluble fractions pretreated with phenobarbital (PB) and 3-methylcholanthrene (3-MC) by high pressure liquid chromatography. The experimental results indicated that the major metabolic pathway of Yekuling in vitro was hydrolysis. PB can enhance amidase activity to increase formation of benzoic acid and 1,3-dithiolan-2-ylidenehydrazine. 3-MC treatment elevated rat liver microsomal cytochrome P-448, enhancing S-oxidation of Yekuling. On the other hand, S-oxidation of Yekuling by rat liver microsomal MFO was NADPH-dependent.


[Protective action of seed oil of Hippophae rhamnoides L. (HR) against experimental liver injury in mice]. Protection by seed oil of HR against hepatic injury induced by CCl4, ethyl alcohol and acetaminophen (AAP) on mice was studied in this paper. It was found that seed oil of HR markedly inhibited MDA formation of liver induced by CCl4, AAP and ethyl alcohol, seed oil 4.75 g/kg could lower SGPT levels induced by CCl4 and AAP. It blocked also depletion of GSH damaged liver induced by AAP. The mechanism of heptoprotective actions of HR seed oil might be related to anti-lipid peroxidation.


[Hygienic investigation and evaluation of houses of Turfan countryside in Xinjiang]. Turfan Basin of Xinjiang is the hottest place in China. Hygienic investigation on two kinds of house in countryside and determination of indoor air quality were conducted. The physiological reaction of local people was also evaluated. The results showed that cave dwellings were warmer in the winter and cooler in the summer, but natural lighting and ventilation were poor. In the winter, indoor air pollution was more severe. The physiological responses of local people to two kinds of houses did not show any significant difference.


Automated determination of oxytetracycline residues in muscle, liver, milk and egg by on-line dialysis and post-column reaction detection HPLC. An automated method for control of oxytetracycline (OTC) residues in chicken and bovine muscle, salmon liver, bovine milk and hen egg has been developed. Tissue homogenate, decreamed milk or whole egg solution was dialysed and the dialysate enriched on a small polystyrene column on-line to HPLC. OTC and the internal standard (tetracycline) were separated on a polystyrene column by ion-pair chromatography. The column effluent was mixed with sodium hydroxide and irradiated at 366 nm. Monitoring the resulting derivatives with a fluorescence detector (excitation: 358 nm, emission: 460 nm), OTC could be detected at 1 ng/ml in milk, 1 ng/g in egg, 3-4 ng/g in muscle and 8 ng/g in liver. Relative standard deviations at 50 and 200 ng/g (milk: 20 and 100 ng/ml) ranged from 1.6 to 3.1%.


Depletion of protein-bound furazolidone metabolites containing the 3-amino-2-oxazolidinone side-chain from liver, kidney and muscle tissues from pigs. Ten 3-month-old pigs were treated with feed containing 300 mg furazolidone per kg for a period of 7 days, followed by withdrawal periods of 0, 1, 2, 3 or 4 weeks (two per group). The treatment resulted in the formation of protein-bound metabolites containing an intact 3-amino-2-oxazolidinone (AOZ) side-chain that could be chemically released and then detected in liver, kidney and rump muscle tissues even 4 weeks after dosing. In tissues from animals killed at the end of the medication period, 993, 600 and 124 ng of AOZ were released from 1 g of liver, kidney and muscle respectively. In the tissues of the animals killed after a further 4 weeks the corresponding levels were 41, 7 and 10 ng/g respectively. It may be concluded that long withdrawal periods prior to slaughter for human consumption are required for pigs treated with furazolidone, because of the long residence time of protein-bound AOZ and the possibility that it might be released from its protein-bound form in the stomach and subsequently be transformed into a hydrazine.


Natural occurrence of Fusarium mycotoxins of the 1990 barley crop in Korea. During the barley harvest in June 1990, there was a great deal of rainfall and high humidity in the southern part of Korea, and natural occurrence of Fusarium mycotoxins was suspected in barley samples. The samples of undergrade barley were obtained from four provinces and analysed for the presence of deoxynivalenol (DON) and nivalenol (NIV) by gas chromatography and zearalenone (ZEN) by high performance liquid chromatography. Of 37 samples, 33, 37 and 10 were positive for DON, NIV and ZEN, respectively. The husked barley contained 29-677 ng/g for DON, 114-1546 ng/g for NIV and 183-1416 ng/g for ZEN. The naked barley contained 38-645 ng/g for DON, 85-4569 ng/g for NIV and 40-1081 ng/g for ZEN. The average concentration of NIV in naked barley was higher than that in husked barley, but the average concentration of DON in husked barley was higher than that in naked barley. The survey indicates that the 1990 barley crop in Korea was heavily contaminated with Fusarium mycotoxins.


Production of trichothecene mycotoxins by Australian Fusarium species. Australian isolates of Fusarium species were grown on potato dextrose agar. Trichothecenes produced by these species were extracted by ethyl acetate followed by methanol and a silica gel column was used to clean-up the extract. The extracted samples were derivatized by acetylation with trifluoroacetic anhydride and the derivatives analysed by gas chromatography/mass spectrometry (GC/MS). Multiple ion detection was used to trace ions characteristic of the trichothecenes expected to be present. Quantitation of those found was based on a known mass of pentabromophenol that was added as an internal standard. Eight species of Fusarium (nineteen strains) were surveyed, of which three species, F. acuminatum, F. equiseti and F. sporotrichioides, produced the trichothecenes scirpentriol, diacetoxyscirpenol, neosolaniol, HT-2 toxin, T-2 toxin, T-2 tetraol and deoxynivalenol. Wheat samples were inoculated with four different species of Fusarium, F. acuminatum, F. equiseti, F. graminearum and F. sporotrichioides, and in these samples diacetoxyscirpenol, neosolaniol, HT-2 toxin and T-2 toxin were found.


Occurrence of the mycotoxins ochratoxin A, zearalenone and deoxynivalenol in feed components. The mycotoxin contamination of feed components used by the Dutch cooperative feed industry was surveyed to estimate the risk for animal production losses. Of 89 randomly and 6 selectively taken samples of raw materials harvested in 1988 and 1989 27% were contaminated with ochratoxin A (OCHRA), 31% with zearalenone (ZEA) and 20% with deoxynivalenol (DON). The mean content (microgram/kg) of all positive randomly taken samples was 18 (OCHRA), 62 (ZEA) and 630 (DON). The highest level (microgram/kg) for all samples was 120 (OCHRA) in barley, 3100 (ZEA) in corn cob mix and 1900 (DON) in maizegluten feed. The results of this survey show that feed components are often contaminated with mycotoxins. However, the contamination level could only sporadically cause production losses in animal husbandry.


Monitoring sweetener consumption in Great Britain. A comprehensive survey of the consumption of intense sweeteners in Great Britain in 1988 quantified the levels of usage of different sweeteners and identified their distribution between food categories and population subgroups. Saccharin was found to be the most widely used intense sweetener. Beverages were the most common source of intense sweeteners. The quantities consumed of all sweeteners were found to be below the Acceptable Daily Intake (ADI) values established by the Joint FAO/WHO Expert Committee on Food Additives, the European Commission Scientific Committee for Food or the UK Committee on Toxicity of Chemicals in Food, Consumer Products and the Environment.


Do saxitoxin-like substances have a role in scombrotoxicosis? Evidence is presented which establishes that mackerel fed in captivity can, by relay from contaminated shellfish via sand eels, accumulate paralytic shellfish poisons (PSP) in the edible flesh at a level (250 micrograms saxitoxin equivalents per kg) similar to that in the contaminated shellfish. Data from ELISAs performed independently in two laboratories show that commercial mackerel fillets which have been associated with incidents of scombrotoxicosis contained 0.02-1.30 micrograms saxitoxin equivalents per kg, concentrations some two to four orders of magnitude below that normally detectable by the mouse bioassay. The doses, expressed as saxitoxin equivalents, administered inadvertently during volunteer testing of such fillets ranged up to 0.5 ng/kg bw, at least four orders of magnitude less than the fatal oral dose for an adult. The doses associated with the rapid induction of nausea/vomiting and/or diarrhoea, 0.11-1.0 ng/kg bw, could not be distinguished from the doses which failed to produce such symptoms in susceptible volunteers (up to 0.5 ng/kg bw). Factors that might explain this lack of correlation between dose (saxitoxin equivalents) and volunteer response are discussed along with previously published reports of PSP relay through the food web. It is suggested that the relay of algal toxins, particularly PSP, but possibly in combination with diarrheic shellfish poisons, may be responsible for scombrotoxicosis.


[The adaptation of Cooper's mile test for students in the city of Mexico]. The Cooper is test (running 1609 m) was applied to 1196 students, 15 to 17 years old, performed the Cooper's test (1609 m race). The scale, designed adequately for this sample of Mexican population, allows to judge the physical fitness by means of an easy and economical procedure.


[The treatment of colonic and ovarian cancer with radioactive monoclonal antibodies against the CA l9-9 and CA 125 antigens]. The age of monoclonal antibodies arose with the papers by Köhler and Milstein in 1975. By means of a fusion between a neoplastic cell with one which produced a specific antibody they obtained a hybrid or clonal cell. Five years later, Nadler et al issued the first report of a patient with lymphoma treated with monoclonal antibodies. After the first announcement, diverse research centers have reported the clinical results obtained in various neoplasias treated with radioactive monoclonal antibodies directed against antigens associated with neoplasias, as well as non-specific tumoral antigens, including lymphomas, melanomas and cancers of the colon, ovary and breast.


Thymic histology in myasthenia gravis.

Thymic histology in myasthenia gravis. Histological features of resected thymuses of 18 patients with myasthenia gravis were evaluated. Thymoma were seen in 16.6% of the patients. In the non-thymomatous group, thymic hyperplasia with follicle formation was seen in 33.3%, involuted thymus with occasional lymphoid follicle formation in 11.1%, thymitis with B cell infiltration in 16.6%, involuted thymus in 11.1% and normal thymus in 11.1% of patients. Immuno-histological staining for B and T lymphocytes delineated the group labelled as thymitis with B cell infiltration. Mast cell and eosinophils were frequently seen in thymuses with thymic hyperplasia with follicle formation and thymitis with B cell infiltration. Thymic hyperplasia with follicle formation was more frequent in young patients and these patients had better prognosis.


Adenosine deaminase activity in pleural fluid--a diagnostic test of tuberculous pleural effusion. Adenosine deaminase (ADA) activity in pleural fluids was studied in 47 patients with pleural effusion of different etiology. Patients were divided into two groups: Group I - Tuberculous pleural effusion (21 patients): Group II - Non tuberculous effusion (26 patients) and these included malignant pleural effusion (9 cases), synpneumonic pleural effusion (9 cases) and transudative pleural effusion (8 cases). The mean ADA activity was 64.67 IU/L +/- 21.68 in group I and 6.99 +/- 3.69 in Group II. Increased mean pleural fluid ADA activity in tuberculous pleural effusion was highly significant (p < 0.001) when compared with pleural effusion of non-tuberculous etiology. Based on lowest value of ADA activity found in tuberculous pleural effusion (30 IU/L), the test has a sensitivity and specificity of 1.


Aetiological diagnosis in permanent residents of Punjab presenting with chest complaints and high peripheral blood eosinophilia. Sixty-six permanent residents of Punjab, presenting with chest complaints and absolute eosinophil counts (AEC) over 2000 per cumm were investigated to find out the cause of high eosinophilia. Tropical pulmonary eosinophilia (TE) was responsible for high eosinophilia in 27 cases (40.9%), even in this region where filariasis is not endemic. Severe asthma (23 cases), allergic bronchopulmonary aspergillosis (ABPA-5 cases), drug reaction (2 cases) and chronic eosinophilic pneumonia (2 cases) in adults and ascariasis (6 cases) in children were other main causes of high eosinophilia. It is emphasized that all cases with high blood eosinophilia should not be labelled as cases of TE simply on the basis of AEC over 2000 per cumm. This is all the more important for non-filarial regions. Only a systematically conducted work up can clinch the correct diagnosis in such cases.


Effect of treatment on pulmonary functions in chronic severe anaemia. Pulmonary functions were measured in 15 patients with severe chronic anaemia (haemoglobin level < 5 g/dl). The measurements were repeated after correction of anaemia (Hb > 10 g/dl). Twenty age and sex matched, asymptomatic, non-smoker subjects served as controls. There was 80-100% improvement in various lung functions after correction of anaemia. Effort dependent parameters, viz FVC, ERV, IC, MVV were low in anaemic patients which improved with the rise of haemoglobin. The TLCO, DM, VC, KCO were not significantly influenced during anaemic state. FEV1, PEFR, RV/TLC were essentially normal. We conclude that the observed changes produced in lung functions during anaemic state are fully reversible after its correction.


Adrenocortical insufficiency in smear positive pulmonary tuberculosis. We studied 40 patients with pulmonary tuberculosis. All were positive for acid-fast bacilli (AFB) in the sputum. Their mean age was 30 yrs (range 10-50 yrs) and the duration of illness was 26.3 +/- 2.3 months. Radiologically minimal, moderately advanced and far advanced lesions were present in 7 (17.5%), 9 (22.5%) and 23 (57.5%) patients respectively. One patient with endobronchial lesion had no radiological evidence of pulmonary tuberculosis. Clinically, 14 patients (35%) had one or the other features of adrenocortical insufficiency. Postural hypotension was the commonest feature and was present in 11 patients (27.5%), followed by nausea and vomiting (20%), loss of axillary hair and libido (10%), skin and mucosal pigmentation in 7.5% of the cases. ACTH stimulation revealed incomplete adrenocortical insufficiency (partially responsive adrenal) in 5 patients (12.5%) and complete adrenocortical insufficiency (non-responsive adrenal) in 2 patients (5%). Patients with features of adrenal insufficiency had significantly longer duration of illness (p < 0.001) but there was no correlation with extent or type of lesion.


Congenital asymptomatic absence of pericardium. An interesting congenital anomaly of the pericardium is its absence. One such case is reported here. Recent literature is reviewed also.


Posterior mediastinal teratoma.

Posterior mediastinal teratoma. A patient with benign posterior mediastinal teratoma which is a rare site for teratomas is reported. Chest skiagram and CT of the thorax established the diagnosis. Complete removal of the mass was not possible on surgery as it was adherent to the pericardium and the esophagus. The patient remained asymptomatic one year after the surgery. There was no evidence of recurrence of the tumor.


Domiciliary mechanical ventilation in a patient with severe chronic obstructive lung disease and respiratory failure. A patient of chronic obstructive pulmonary disease (COPD) with cor-pulmonale and chronic respiratory failure, who was given intermittent positive pressure ventilation at home, is reported. The patient did remarkably well on home mechanical ventilatory support. We believe this to be the first case report of domiciliary mechanical ventilation in a patient of COPD from India.


Unilateral pulmonary edema--a report of two cases. We report two cases of unilateral pulmonary edema, one in patient with chronic renal failure which was mistaken for pulmonary tuberculosis and the other in a patient with congestive heart failure. We have reviewed the relevant literature.


Selective suture cutting for control of astigmatism following cataract surgery. Use of 10-0 monofilament nylon in ECCE cataract surgery leads to high with the rule astigmatism. Many intraoperative and post operative methods have been used to minimise post operative astigmatism. We did selective suture cutting in 38 consecutive patients. Mean keratometric astigmatism at three and six weeks post operative was 5.76 and 5.42 dioptres (D) respectively. 77.5% of eyes had astigmatism above 2 D. Selective suture cutting along the axis of the plus high cylinder was done after six weeks of surgery. Mean post suture cutting keratometric astigmatism was 3.3 D and 70% of the eyes had astigmatism below 2 D. After 3 months of surgery mean keratometric astigmatism was reduced to 1.84 D. Axis of the astigmatism also changed following suture cutting. 40% of the eyes showed improvement in their Snellen acuity following reduction in the cylindrical power.


Maximal mydriasis evaluation in cataract surgery. We propose the Maximal Mydriasis Test (MMT) as a simple and safe means to provide the cataract surgeon with objective and dependable pre-operative information on the idiosyncratic mydriatic response of the pupil. The MMT results of a consecutive series of 165 eyes from 100 adults referred for cataract evaluation are presented to illustrate its practical applications and value. The results of the MMT allows the surgeon to anticipate problem eyes pre-operatively so that he can plan his surgical strategy more appropriately and effectively. Conversely, the surgeon can also appropriately and confidently plan surgical procedures where wide pupillary dilation is important. The MMT has also helped improve our cost-effectiveness by cutting down unnecessary delays in the operating room and enabling better utilisation of restricted costly resources.


Clinico-immunological aspects of vernal catarrh in hilly terrains of Himachal Pradesh. Very few immunological studies in vernal catarrh have been conducted in India and abroad, but none in Himachal Pradesh in spite of its high incidence in the State. In the present study 25 patients of vernal catarrh residing at a height ranging between 1000 to 2500 meters above mean sea level have been evaluated. Their immunological status of serum and tears after detailed clinical assessment was studied by single radial immunodiffusion technique of Mancini et al. The values of serum IgA and IgM were significantly higher in patients than in controls. The serum IgE level had no significant difference. The IgG was significantly lower in patients with vernal catarrh. The values of tear IgM, IgE and IgA in these patients were significantly higher than in controls. However, in no case or control group C3C and C4 were detected in tears. The limbal type of vernal catarrh was found to be the most common in this part of the country. No mixed case was seen. Derangement of the immune system in the pathogenesis of vernal catarrh is suggested.


Tuberculoma of orbit.

Tuberculoma of orbit. An interesting case of tuberculoma of the orbit, involving the whole of the eyeball with other orbital cavity structures, is being presented. This is very rarely seen in clinical practice.


Role of orthoptic treatment in the management of intermittent exotropia. 30 patients of intermittent ACDS were studied prospectively for a period of 8 weeks to 1 year to evaluate the role of orthoptics in the management of these cases. In patients with convergence insufficiency and a maximum deviation of 25 PD or less the orthoptic treatment was found to be effective in offering symptomatic relief and improving binocular functional status. A reduction in the maximum angle of deviation by 4 PD to 8 PD was observed in 4 patients. Even though the basic angle of deviation remained unchanged in most of the patients, significant functional and symptomatic improvement was obtained in 64% to 85.7% of these cases. The long term stability of these results remains to be studied. In patients with a deviation of more than 25 PD there was no significant improvement in symptoms or reduction in maximum angle of deviation. In 6(37.5%) of these patients some improvement in the fusional range could be demonstrated on the synoptophore without any symptomatic relief.


An unusual orbito-cranial foreign body.

An unusual orbito-cranial foreign body. The rarity of orbito-cranial gun shot injury in both war and civilian practice has been reported. In a large series of 351 missile head injuries in the Vietnam war, orbital penetration was noted in 0.6% cases only. Review of literature shows that orbital injury was ipsilateral to the cerebral injury in most reported cases. We have previously reported a rare case of left parieto-occipital lobe injury due to gun shot wound of the contralateral (right) orbit. The case reported here sustained a bullet injury to the left frontal bone but the missile was located below the contralateral (right) optic canal. The rarity of the case prompted this report.


Bilateral acute retinal necrosis--a case report. A 42 year old man presented with acute bilateral uveitis and necrotizing retinitis. Systemic investigations including test for AIDS and CMV retinitis were negative. Despite oral Acyclovir, both eyes progressed rapidly to retinal detachment with loss of vision. Early recognition is necessary to diagnose the bilateral acute retinal necrosis syndrome and initiate treatment. Bilateral acute retinal necrosis (BARN) is a term first coined by Young and Bird in 1978 although the syndrome had been originally described by Urayama et al as an unilateral condition. This syndrome is characterized by the triad of acute confluent peripheral necrotizing retinitis, moderate to severe vasculitis and vitritis in an otherwise healthy individual. Rhegmatogenous retinal detachment occurs within two to three months of the onset of the disease and the second eye is involved in 36% of patients, usually within 6 weeks. We herein report a patient who presented with simultaneous BARN leading to retinal detachment in a matter of days. Also, to our knowledge this is the first report of this condition in India.


Blepharoptosis repair by modified sutureless Fasanella-Servat Operation (F.S.O)--a large series of 50 cases. A modified technique of sutureless Fasanella-Servat Operation (F.S.O.) using special curved haemostat for the correction of mild to moderate acquired ptosis with good Levator Palpebrae Superioris (L.P.S.) action (12 m.m.) was performed in a large series of 50 eyes. Excellent correction was achieved in 94.6% eyes with mild ptosis & 61.6% eyes with moderate ptosis. No operative and post operative complications were observed. The technique was found to be very safe, quick and effective.


Modernization and status change among aged men and women. This study investigates the differences between the relationship between elderly occupational status and modernization for men and women. Consonant with previous findings, it finds that economic development is associated with relative losses of elderly men in professional and technical occupations. Augmenting those findings, however, it finds an even stronger association between development and such losses for women. In accounting for the differences, several explanations are advanced and tested, using data from fifty-one nations.


Analysis of retroviral proteins by two-step DNA, zinc binding, and modified Southern-western blotting. Using Southern-Western and zinc-blotting techniques, the interactions of single-stranded DNA and zinc with structural proteins of type B, C, and D retroviruses were examined. Besides nucleic capsid proteins of retroviruses known to form complexes with nucleic acids, some other core proteins of type C retroviruses were shown to bind nucleic acids. All nucleic capsid proteins of the examined retroviruses appeared to be also zinc binding. In the present report, we propose two protein-blotting techniques that could be performed on a single nitrocellulose membrane. A first technique allows to detect zinc- and DNA-binding proteins immobilized on the membrane; a second (a modification of Southern-Western blotting) makes it possible to detect DNA-binding proteins followed by immunological reprobing.


Outcomes of equity/inequity among older spouses. The extent to which perceptions of global and specific equity/inequity were associated with dissatisfaction, disagreement between spouses, partners' regard for one another, and gender-role attitudes was investigated for eighty-two couples over age sixty. The differential influence of equity/inequity for the well-being of women and men was studied.


Molecular cloning and restriction enzyme analysis of bovine adenovirus type 3. Bovine adenovirus type 3 (BAV3) is a DNA virus that causes respiratory and gastrointestinal disorders in cattle. The viral genome consists of a linear double-stranded DNA molecule (35,000 base pairs) with inverted terminal repeats at each of its 5' molecular ends. We have subcloned 10 HindIII fragments spanning 4.9-96.0%, 5 EcoRI fragments spanning 3.4-89.5% and 2 XbaI fragments spanning 35.7-82.9% of the BAV3 (strain WBR-1) genome into the bacterial cloning vector pUC19. The subcloning of the viral genome facilitated the construction of linear restriction enzyme maps for BamHI, ClaI, EcoRI, HindIII, KpnI, NotI, NspV, PstI, PvuI, SalI, XbaI and XhoI. In this study we report on the molecular cloning and restriction endonuclease mapping of the BAV3 genome.


The concept of compensation in cognitive aging: the case of prose processing in adulthood. Although the rule of cognitive aging appears to be one of generalized decline with advancing age, much recent theoretical and empirical work has addressed a variety of potential exceptions to this rule. One mechanism through which decline might not be experienced is known as compensation. We describe a conceptualization of compensation that applies to lifespan cognitive development, in general, and the aging of prose processing skills, in particular. Our model of the forms and processes of compensation directs attention to the developing dynamics of cognitive skills and compensatory mechanisms. We outline three main approaches to research on compensation in cognitive aging: a) the logical experimental, b) on-line observation and manipulation, and c) several verbal report procedures. In summarizing our own research program, we emphasize that a) each of these approaches can render valuable information, b) each have some limitations, and c) there are potential theoretical benefits from employing more than one of them in a given study.


Computerization of virus data and its usefulness in virus classification. Data on 537 Arboviruses and 180 other viruses have been collected and coded in two different formats. These data include information not only regarding the taxonomy and history of isolation, but also regarding the properties of biomacromolecules, proteins and nucleic acids. Information on antigenic relationships, histopathology and experimental viremia is also included. This information is stored in formats which allow the manipulation and analysis of data by dBASE III PLUS and MICRO-IS. A set of programs was written for interconversion and editing purposes. Transmission electron micrographs are scanned and stored. This stored information can be used in viral classification as shown by carrying out analysis of data on the Bunyaviridae family.


Perceived control and adaptation in elder caregivers: development of an explanatory model. Perceived control has been implicated in the adaptation and well-being of older adults and may be especially relevant to elder caregivers. However, few studies have investigated perceived control within the individual's unique personal, social, and environmental context. This study tested a model representing the hypothesis that perceived control, defined as the perception that salient or valued aspects of one's life are manageable, mediates the objective and subjective aspects of caregiving and caregiver adaptation. Sixty elderly caregivers ranging in age from sixty to eighty-four (M = 69.4) were interviewed. Perceived control had a direct relationship with life satisfaction and depression, and an indirect relationship with subjective symptoms of stress. Wishful thinking coping behavior had a negative relationship with all adaptation variables. Findings are discussed in relation to further refinement and development of a theoretical approach to caregiver research and intervention studies in light of the obtained path model.


Koolpinyah: a virus related to kotonkan from cattle in northern Australia. Two closely related viruses were isolated from the blood of bovines near Darwin, Northern Territory, Australia. When studies of virus morphology indicated that these were rhabdoviruses, serologic studies were done. These isolates are closely related or identical and are related to, but distinct from, the rabies-related kotonkan virus. Other serologic studies showed that these are two isolates of a newly recognized virus, for which the name Koolpinyah virus is proposed.


Experimental intercomparisons of younger and older driver perceptions. Drivers over sixty-five years of age and drivers under twenty-one years of age have the highest relative frequency of crashes resulting in injury and death. Attitudes of these two groups were investigated using questionnaires. One hundred twenty-seven (127) younger and one hundred eight (108) older drivers who had voluntarily registered in driving education courses satisfactorily completed questionnaires about attitudes and behaviors pertinent to safe driving. Half of each sample rated the average driver in their age group and the average driver in the opposite age group as regarded thirty-three attitudes promoting safe driving, twenty courteous safe driving behaviors and eleven discourteous, unsafe driving behaviors. Data shows that younger drivers viewed older drivers as overly cautious, too slow to act and apt to cause accidents, and rated their peers as overly aggressive and discourteous. Older drivers characterized younger drivers as deficient in courtesy and safe driving practices, and they rated their peers as cautious, courteous, and aware of age-related limitations. The findings indicate that each group was aware that safety hazards are created by drivers in their age group. It also shows that both groups had a positive impression of some driving practices of their age group, and that the other group was depreciated. The outcome confirms and expands upon conclusions derived from less formal studies about how drivers perceive other roadway users. It also specifies the extent to which particular attitudes and driving practices are attributed to the peer group and to the opposite age group.


Self-efficacy: a predictor but not a cause of behavior. The concept of self-efficacy, as expounded by Bandura as part of his Social Cognitive Theory, has made considerable impact in the psychological literature. It is argued that self-efficacy is a useful hypothetical construct for predicting behavior, but it has no valid claim to being a cause of behavior. Claims for self-efficacy as a causal agent have failed to acknowledge that self-efficacy itself is an epi-phenomenon of performance. Conventional learning theory explanations of observed performance levels are shown to be more parsimonious than accounts relying on the concept of self-efficacy.


On cognitive theories and causation in human behavior. Modern theories of social behavior are based on the largely unquestioned assumption that human activity is determined by cognitive variables. Physiology, environment, and behavior are seen as peripheral to the understanding of cognition, seen as central to the understanding of human nature. This paper argues that these approaches to psychology are essentially metaphorical models of behavior, inadequate as explanatory theories, because they rely on untestable assumptions concerning the centrality to human behavior of hypothetical and unmeasurable cognitive variables. Their lack of precision does not allow for the testing of specific predictions. This paper argues that contemporary cognitive-behavioral and cognitive-social theories cannot be salvaged as explanatory models.


Physically aggressive elderly: a social skills training program. The present investigation utilized a social skills training program to eliminate physically aggressive behavior in a group of six institutionalized elderly patients. The treatment package consisted of instructions, modeling, role playing and feedback. Dependent measures included confirmed incidents of physically aggressive behavior monitored across an ABAB design with a 5-month follow-up period. Results indicated that physically aggressive behavior can be significantly decreased in a group training setting and subsequently generalized to ward and other socialized behavior. Ancillary aspects of the study include the differential properties associated with physical and verbal aggression, the role of vicarious reinforcement on behavior, and generalization effects.


Assessment and prediction of outcome for a brief behavioral insomnia treatment program. This study examined (a) the efficacy, and (b) predictors of outcome of a brief (one to four sessions) behavioral treatment program for chronic insomnia. A total of 103 insomnia patients were treated, and outcome was assessed by a follow-up questionnaire. Outcome variables, including both nocturnal sleep parameters and measures of daytime functioning, showed significant improvement subsequent to treatment. Pretreatment sleep hygiene practices were significantly correlated with daytime fatigue and sleep latency outcome factors. Pre- and post-treatment complaints of daytime fatigue were associated with somatic complaints in general, but not with nocturnal sleep variables. Explanatory hypotheses are discussed.


The possible function of positive reinforcement in home-bound agoraphobia: a case study. We conducted an uncontrolled case study (ABA design) based upon the hypothesis that the behavior of a home-bound agoraphobic is at least partially maintained by positive reinforcement in the home and that a disruption of access to home-based reinforcement would lead to an increased frequency of out-of-the-home behavior. Data concerning the types and amounts of behavior engaged in by the subject within the confines of her home and yard were gathered during a 30-day base line period. In addition, potential reinforcers in the home were identified by a survey schedule and by self-report of time allocation. During an 18-day intervention period the subject agreed only to engage in certain reinforcing activities outside her home (e.g., only watching television at a neighbor's house). Postintervention results indicated that for the first time in over 7 years the subject began engaging in out-of-home activities, including walking to other parts of the street, visiting several neighbors' homes, and attending parties at neighbors' homes. Moreover, data suggested a positive trend in time spent outside the yard during both 2 and 18 month follow-up periods. However, significant restrictions in the range of mobility were still observed.


The treatment of bulimia nervosa following surgery using a stimulus control procedure: a case study. This single case report describes the treatment of a 35-year-old female, who was diagnosed as suffering from severe bulimia nervosa. Of interest were the frequent vomiting episodes which did not exist prior to two surgical operations performed on the client in order to reduce her overall body weight. The treatment, a stimulus control procedure, which spanned 20 sessions, lasted about 24 weeks and was deemed successful after a year follow-up. Of primary importance was the self-management aspect of the treatment program, which emphasized minimum therapist intervention. In addition, there was a complete absence of "cognitive components" deemed necessary by some authors for the long-term treatment success of bulimics. Different factors relating to the success of this treatment program are also reviewed.


Cyclical self-injurious behavior, contingent water mist treatment, and the possibility of rapid-cycling bipolar disorder. Cyclical self-injurious behavior (SIB) in the form of self-slapping was treated in a 45-year-old, profoundly retarded woman who had a life-long history of SIB. Her SIB alternated between high (mean = 8.54 responses per min; SD = 6.77 and low (mean = 0.05 responses per min; SD = 0.20) frequencies every 8 weeks on average. Instances of self-slapping produced water mist treatment paired with a verbal command, "No hitting". Absence of self-slapping and/or completion of a work task led to a variety of outcomes, including brief back rubs, sips of water, small edibles, and praise. Water mist treatment reduced the frequency of SIB within treatment days during high frequency periods, but produced no reduction across treatment days. Treatment onset was associated with a slight increase in the frequency of SIB during three of the five low frequency periods. However, water mist treatment suppressed SIB completely in sessions during low frequency periods and the suppression continued across treatment days. Water mist treatment produced no discernible changes in the length of the high and low frequency periods of SIB.


Hyperoxemia profoundly alters breathing pattern and arouses the fetal sheep. We have recently shown that hyperoxemia alone or combined with umbilical cord occlusion causes continuous breathing and arousal in the fetal sheep (Baier, Hasan, Cates, Hooper, Nowaczyk & Rigatto, 1990). We have not however analyzed the changes in the pattern of breathing associated with these events. To do this, we measured the changes in breathing pattern, electrocortical activity and behaviour on 29 occasions in 15 fetal sheep in late gestation. Fetuses were studied during rest, and during lung distention (about 30 cm H2O) with 100% nitrogen (control), 17% oxygen, 100% oxygen and umbilical cord occlusion. Lung distention was obtained using a high frequency oscillator (Senko Co) and in some fetuses a stroke volume of 0 to 20 cm H2O was used to keep PaCO2 near-constant. We found that lung distention with nitrogen or 17% oxygen did not alter the pattern of breathing or behaviour. In 12 out of 34 (35%) experiments 100% oxygen induced continuous breathing, PaO2 increasing to about 250 torr. In the remaining 22 experiments, PaO2 increased to about 100 torr only and breathing was not continuous but it became continuous upon cord occlusion; with occlusion there was a further increase in PaO2 to 190 torr. The increased breathing with oxygen and occlusion was associated with an increase in breathing output (integral of EMGdi x f), an increase in inspiratory drive (integral of EMGdi/Ti), and a decrease in inspiratory (Ti) and expiratory (Te) times. In ten experiments PaCO2 was kept near-constant and the magnitude of the changes remained.(ABSTRACT TRUNCATED AT 250 WORDS)


Neuropeptide Y and catecholamine release in the piglet during hypoxia: enhancement by theophylline. Sympathoadrenal activity was studied in 13 young piglets during hypoxia. The piglets were anaesthetized with chloralose/urethane, tracheostomized, paralyzed with gallamine and artificially ventilated. A femoral artery catheter was inserted and used for blood sampling. The piglets were challenged with 6 min of 6% CO2, 10 min of 12% O2 and 6 min of 6% O2 before and after theophylline (an adenosine receptor antagonist) treatment 20 mg/kg (n = 9) or saline (n = 4). Plasma samples were obtained before, during and after each hypercapnic or hypoxic period and analysed for their content of noradrenaline, adrenaline and neuropeptide Y. Hypercapnia with 6% CO2 and moderate hypoxia with 12% O2 did not lead to any significant increase of either noradrenaline (NA), adrenaline (A) or neuropeptide Y (NPY). However, severe hypoxia with 6% O2 increased the NA level from 30 to 66 nmol/l; the A level from 1 to 28 nmol/l and NPY from 140 to 213 pmol/l. After treatment with theophylline the baseline NA increased from 27 to 40 nmol/l, A rom 1.5 to 4.0 and NPY concentration from 65 to 171 pmol/l. Theophylline moderately enhanced the release of NPY, NA and A during the 12% O2 challenge. However, during the severe hypoxia (6%), the increase of NA (from 49 to 333 nmol/l), A (from 8 to 214 nmol/l) and NPY (from 184 to 385 pmol/l) showed considerably enhancement after the theophylline treatment. The results obtained before and after saline were similar showing that the duration of the experiments per se did not change the baseline levels or the effect of the challenges on NA, A or NPY levels.(ABSTRACT TRUNCATED AT 250 WORDS)


Effects of tetrodotoxin, Ca2+ absence, d-tubocurarine and vesamicol on spontaneous acetylcholine release from rat muscle. 1. Rat hemidiaphragms were incubated in a physiological low-K+ medium without stimulation and the amount of acetylcholine (ACh) released was measured radioenzymatically. Cholinesterases were inhibited by paraoxon. 2. In the presence of 1 microM tetrodotoxin (TTX), the amount of ACh released during a 2 h incubation was lowered by 40%. A similar decrease was observed in the absence of Ca2+ and in the presence of 10 microM-d-tubocurarine (dTC). The effects of TTX combined with Ca2+ removal, and of TTX combined with dTC were no greater than those of TTX, dTC or Ca2+ removal alone. TTX and dTC had no effect on the release of ACh from diaphragms 4 days after denervation. 3. The reduction of spontaneous ACh release observed in the presence of TTX or dTC or in the absence of Ca2+ is best interpreted on the assumption that about 40% of the ACh release was due to the impulse activity known to be generated in intramuscular motor nerve branches by the ACh which accumulates after the inhibition of cholinesterases. 4. In the presence of 1 and 10 microM vesamicol (AH5183, 2-(4-phenylpiperidino)-cyclohexanol), the release of ACh was also diminished by approximately 40%. Vesamicol did not augment the inhibition of release produced by TTX or by the omission of Ca2+.(ABSTRACT TRUNCATED AT 250 WORDS)


Tension responses of sheep aorta to simultaneous decreases in phosphocreatine, inorganic phosphate and ATP. 1. Tension responses of sheep aortae were investigated when different substrates were included in the superfusing medium. The magnitude of tension development was similar whether or not 5 mM glucose was present in the medium. However, the rate of tension development was greater in the absence of glucose. 2. When 5 mM 2-deoxyglucose (2DG) was present in the medium, the magnitude of tension generation was 1.6 times that in the absence of exogenous substrate. A second sequential contraction with 2DG generated tension 1.25 times that in the absence of exogenous substrate. The rate of tension development during the first contraction in the presence of 2DG was similar to that in the absence of substrate. However, the second contraction in the presence of 2DG had a substantially increased rate of tension development. 3. 31P nuclear magnetic resonance (NMR) spectroscopy revealed that, at resting tone, in the presence of 2DG, inorganic phosphate (P(i)) and phosphocreatine (PCr) simultaneously decrease while 2-deoxyglucose-6-phosphate accumulates. During contraction-relaxation cycles, in the presence of 2DG, P(i) and PCr become undetectable while ATP declines to approximately 50% of control values as determined by NMR. During the second contraction in the presence of 2DG, the area of the ADP resonance was similar to that of the alpha-ATP resonance. 4. The increase in the magnitude of tension generation, during 2DG administration, correlated with a decrease in P(i) levels. The rate of relaxation from a contraction, in the presence of 2DG, was slower than in the presence of glucose or in the absence of exogenous substrate. These results are consistent with the role of P(i) in the release of the proposed 'latch-bridge' state of maintained contraction at low energy demand. 5. The increase in isometric tension generation during contraction in the presence of 2DG appears to be related to the decreased levels of P(i). In the presence of 2DG, the reduction of PCr and of ATP occur to a similar extent to that during hypoxia, yet no inhibition of force takes place. The low levels of ATP and PCr reported with 2DG administration in these studies do not energetically limit the contractile apparatus.


Responses of slowly adapting type II afferent fibres in cat hairy skin to vibrotactile stimuli. 1. Slowly adapting type II (SAII) afferent fibres that supply the forelimb were isolated from the medial cutaneous nerve of anaesthetized cats and examined for their capacity to signal information about vibrotactile events in the hairy skin. 2. The SAII fibres had a single spot-like receptive field focus where they were highly sensitive to steady indentation and vibration applied with probes normal to the skin surface. However, their sensitivity was affected profoundly by the size of the stimulus probe, its position in relation to the receptive field focus and, to a lesser extent, the magnitude of any pre-indentation on which vibration was superimposed. Small stimulus probes (e.g. 250 microns diameter) were much more effective than larger (> or = 1-2 mm) ones, and small shifts in the position of the perpendicularly applied probe away from the receptive field focus led to a marked decline in responsiveness. 3. With appropriate choice of stimulus parameters for vibratory stimuli applied at the receptive field focus, the SAII fibres could respond at low threshold (< 100 microns), with a tightly phase-locked, regular 1:1 impulse pattern (one impulse per vibration cycle) that accurately signalled the vibration frequency over a bandwidth that extended to 600 Hz. Furthermore, their responses remained phase-locked up to 1000 Hz. Phase-locking in SAII fibres was marginally tighter than that in SAI fibres and comparable to that of Pacinian corpuscle fibres. 4. The sensitivity of forelimb SAII fibres to tangential skin stretch was directionally selective; stretch across the forelimb was much more effective than along its long axis. Vibration associated with tangential skin stretch led to a marked spatial expansion of the field of vibration sensitivity. SAII fibres could therefore signal information about natural stimuli that contain elements of skin stretch and vibration, as may be encountered when the forelimb brushes against textured surfaces. Should the SAII fibres fail to contribute to the sensory experience of vibrotactile stimuli, the explanation may be related to limitations imposed centrally on the processing of their signals. Nevertheless, the present results demonstrate that, with appropriate stimulus conditions, the SAII afferent fibres have much greater vibrotactile sensitivity than has been suggested by past studies.


Intracellular calcium dynamics in response to action potentials in bullfrog sympathetic ganglion cells. 1. Dynamic changes in the intracellular free Ca2+ concentration ([Ca2+]i) following electrical membrane activity, were recorded from the neurone soma of the excised bullfrog sympathetic ganglion, using Fura-2 fluorescence and compared with the accompanying Ca(2+)-dependent electrical membrane responses. 2. The resting [Ca2+]i was about 100 nM, a value little changed by penetration with an intracellular electrode. 3. A net rise in fluorescence at a wavelength of 340 nm (Ca2+ transient) induced by a single action potential in Ringer solution rose almost in parallel with the initial decay phase of a slow Ca(2+)-dependent after-hyperpolarization; decayed in parallel with the late phase; and increased in amplitude and duration in the presence of tetraethylammonium (20 mM). 4. A Ca2+ transient induced by repetitive action potentials was increased asymptotically in amplitude and progressively in duration by increasing the number of spikes, and was slower in time course than the associated Ca(2+)-dependent K+ current. 5. Scanning a single horizontal line across the cytoplasm with an ultraviolet argon ion laser (351 nm) and recording Indo-1 fluorescence with a confocal microscope demonstrated an inward spread of a rise in [Ca2+]i following a tetanus. 6. Both single spike- and tetanus-induced Ca2+ transients were abolished in a Ca(2+)-free solution, while single or repetitive transient rises in [Ca2+]i induced by caffeine (5-10 mM) were generated under the same conditions. 7. Ryanodine (10-50 microM) did not affect tetanus-induced Ca2+ transients, whereas it blocked completely the caffeine-induced oscillation of [Ca2+]i. 8. Ca2+ transients induced by a tetanus in Ringer solution were independent of the interval from the preceding tetanus. The amplitude of Ca2+ transients induced by a tetanus in the presence of caffeine (5 mM) was equal to, or greater than, that generated in Ringer solution in any of the phases of [Ca2+]i oscillation. 9. It is suggested that under the physiological conditions here, the induction of action potentials does not cause the release of Ca2+ in the cells of the freshly excised bullfrog sympathetic ganglion, and that Ca(2+)-buffering systems contribute not only to lowering a transient rise in [Ca2+]i but also to sustaining an increased [Ca2+]i after a large Ca2+ load into the cell.


Responses of macaque ganglion cells to the relative phase of heterochromatically modulated lights. 1. We measured the response of macaque ganglion cells to sinusoidally modulated red and green lights as the relative phase, theta, of the lights was varied. 2. At low frequencies, red-green ganglion cells of the parvocellular (PC-) pathway with opponent inputs from middle-wavelength sensitive (M-) and long-wavelength sensitive (L-) cones were minimally sensitive to luminance modulation (theta = 0 deg) and maximally sensitive to chromatic modulation (theta = 180 deg). With increasing frequency, the phase, theta, of minimal amplitude gradually changed, in opposite directions for cells with M- and L-cone centres. 3. At high frequencies (at and above 20 Hz), phasic cells of the magnocellular (MC-) pathway were maximally responsive when theta approximately 0 deg and minimally responsive when theta approximately 180 deg, as expected from an achromatic mechanism. At lower frequencies, the phase of minimal response shifted, for both on- and off-centre cells, to values of theta intermediate between 0 and 180 deg. This phase asymmetry was absent if the centre alone was stimulated with a small field. 4. For PC-pathway cells, it was possible to provide an account of response phase as a function of theta, using a model involving three parameters; phases of the L- and M-cone mechanisms and a L/M cone weighting term. For red-green cells, the phase parameters were monotonically related to temporal frequency and revealed a centre-surround phase difference. The phase difference was linear with a slope of 1-3 deg Hz-1. If this represents a latency difference, it would be 3-8 ms. Otherwise, temporal properties of the M- and L-cones appeared similar if not identical. By addition of a scaling term, the model could be extended to give an adequate account of the amplitude of responses. 5. We were able to activate selectively the surrounds of cells with short-wavelength (S-) cone input to their centres, and so were able to assess L/M cone weighting to the surround. M- and L-cone inputs added linearly for most cells. On average, the weighting corresponded to the Judd modification of the luminosity function although there was considerable inter-cell variability. 6. To account for results from MC-pathway cells, it was necessary to postulate a cone-opponent, chromatic input to their surrounds. We developed a receptive field model with linear summation of M- and L-cones to centre and surround, and with an additional M,L-cone opponent input to the surround.(ABSTRACT TRUNCATED AT 400 WORDS)


Asymmetry of vascular responses of perfused rabbit carotid artery to intraluminal and abluminal vasoactive stimuli. 1. Responses of the carotid artery of rabbits to intraluminal and abluminal administration of purinergic agonists were examined. The carotid artery was perfused in vitro and changes in diameter were recorded. 2. Intraluminal acetylcholine, ADP, and ATP produced pronounced vasodilatation, whereas abluminal acetylcholine, but not ADP and ATP, produced dilatation of phenylephrine-preconstricted arteries. Intra- and abluminal adenosine and nitroprusside produced equipotent vasodilatation. 3. N omega-nitro-L-arginine abolished dilator responses to acetylcholine and adenine nucleotides, and unmasked vasoconstrictor responses to high concentrations of these agonists. Responses to adenosine and nitroprusside were not affected by nitro-L-arginine. 4. Intraluminal, but not abluminal, administration of nucleotidase-resistant adenine nucleotide analogues 2-methylthio-ATP and ADP beta S produced significant vasodilation in arteries preconstricted with phenylephrine. Intra- and abluminal administration of alpha,beta-methylene-ATP, a potent P2X-purinoceptor agonist, did not produce vasodilatation in preconstricted arteries. 5. Abluminal ADP failed to elicit dilatation of phenylephrine-preconstricted arteries even in the presence of the ADPase inhibitor beta,gamma-methylene-ATP (10(-5)M). When P2X-purinoceptors, which mediate adenine nucleotide-induced vasoconstriction, were stimulated with alpha,beta-methylene-ATP (10(-5)M), abluminal ADP produced vasodilatation, presumably because P2X-purinoceptors were occupied, thereby unmasking P2Y-purinoceptor-mediated dilatation. 6. These results suggest that asymmetric vascular responses of rabbit carotid arteries to adenine nucleotides may be due in part to preferential activation of P2Y-purinergic receptors on endothelium and P2X-purinergic receptors on vascular smooth muscle.


Convergence of visceral and somatic inputs onto subnucleus reticularis dorsalis neurones in the rat medulla. 1. In anaesthetized rats, recordings were made within the medullary subnucleus reticularis dorsalis (SRD) from neurones that exhibited convergence of nociceptive inputs from the entire surface of the body. Neurones with total nociceptive convergence responded to supramaximal percutaneous electrical stimuli (2 ms duration) with early and late peaks due to the activation of A delta and C fibres, respectively, no matter which part of the body was stimulated. Neurones with partial nociceptive convergence responded to identical stimuli with an A delta peak of activation regardless of which part of the body was stimulated and with a C peak of activation from some, mainly contralateral, parts of the body. The characteristics of the responses of these neurones to graded colo-rectal distension (< or = 100 mmHg) were analysed. 2. The majority of neurones with total nociceptive convergence (n = 13 out of 16) responded to colo-rectal distension by increasing their firing rates. Although these neurones were virtually unresponsive to the lowest pressure employed (12.5 mmHg), they increased their discharges monotonically for distensions in the 26-100 mmHg range and these responses were sometimes followed by after-discharges. One of these neurones, which exhibited a high level of spontaneous activity, was inhibited during colo-rectal distension. None of the neurones with partial nociceptive convergence recorded (n = 10) ever changed its firing rate during increases of intracolonic pressure up to 100 mmHg. 3. It is concluded that neurones with total nociceptive convergence give monotonic stimulus-response relationships for colo-rectal distensions. Thus, neurones with total nociceptive convergence can encode the strength of visceral stimuli, probably within the noxious range, just as they have previously been shown to do for thermal and mechanical cutaneous stimuli. Together with previous electrophysiological and neuroanatomical findings, this study provides further evidence for the convergence of noxious inputs onto single SRD neurones. 4. It is suggested that neurones with total nociceptive convergence could be a link in spino-bulbospinal loops involved in autonomic reactions to strong visceral stimulation. In addition, SRD neurones could be an important supraspinal relay in the mechanisms of visceral pain.


Intracellular electrophysiological study of suprachiasmatic nucleus neurons in rodents: inhibitory synaptic mechanisms. 1. The mechanisms responsible for evoked and spontaneous fast inhibitory postsynaptic potentials (IPSPs) in the hypothalamic suprachiasmatic nucleus (SCN) were studied with intracellular recording. SCN neurons, primarily ones identified as receiving excitatory optic nerve input, were recorded in rat and guinea-pig brain slice preparations maintained in vitro. 2. In normal medium, electrical stimulation of a site dorsocaudal to the SCN evoked IPSPs from thirty-three of thirty-six neurons. The evoked IPSPs rose to the peak quickly (8.7 +/- 0.9 ms, mean +/- S.E.M.; n = 15 neurons) and decayed gradually with a time constant of 25 +/- 3 ms. Spontaneous IPSPs were present in each of the thirty-six neurons. These IPSPs had a rise-to-peak time of 7.2 +/- 1.0 ms (n = 6 neurons) and a decay time constant of 14 +/- 5 ms. 3. When recorded with potassium acetate-filled electrodes, the evoked and spontaneous IPSPs were hyperpolarizing at resting membrane potential (less negative than -70 mV) and had a reversal potential of around -75 mV. On the other hand, when recorded with potassium chloride-filled electrodes, the IPSPs were depolarizing at membrane potentials more negative than -50 mV and had an estimated reversal potential less negative than spike threshold. 4. Bath application of bicuculline (10-50 microM), a gamma-aminobutyric acidA (GABAA) receptor antagonist, resulted in a complete blockade of both the evoked (n = 16) and spontaneous (n = 13) IPSPs. The bicuculline effects were reversible, and were not associated with any significant and consistent change in baseline membrane potential or input resistance. The neurons impaled in bicuculline-containing medium (n = 11) exhibited neither spontaneous IPSPs nor evoked IPSPs. 5. In some neurons bicuculline-resistant hyperpolarizing potentials, which were similar to the fast IPSPs in time course, occurred spontaneously or were evoked by electrical stimulation of the optic nerve or the dorsocaudal site. A fast prepotential always preceded the hyperpolarizing potential, and hyperpolarizing currents blocked these events, indicating that they were not synaptic in origin. No slow IPSPs were detected. 6. The results suggest that fast IPSPs from non-retinal afferents exist in virtually all SCN neurons receiving excitatory retinal input, and that GABAA receptors associated with Cl- channels mediate the fast IPSPs.


Mechanism of release of Ca2+ from intracellular stores in response to ionomycin in oocytes of the frog Xenopus laevis. 1. The mechanism of Ca2+ release from intracellular stores was studied in defolliculated Xenopus laevis oocytes by measuring whole-cell currents using the two-electrode voltage-clamp method. 2. The extracellular application of ionomycin, a selective Ca2+ ionophore, evoked an inward current consisting of a spike-like fast component followed by a long-lasting slow component with few superimposed current oscillations (fluctuations). The ionomycin response occurred in a dose-dependent manner and was dependent on Cl-. 3. No apparent refractory period was observed for repetitively evoked small ionomycin responses when the concentration of ionomycin was low (0.1 microM). In contrast, a larger ionomycin response (1 microM), consisting of fast and slow components, was followed by refractory period. Washing for 50-90 min was necessary for full recovery of the ionomycin response. 4. The response to ionomycin was suppressed by the extracellular application of acetoxymethyl ester of bis-(O-aminophenoxy)-ethane-N,N,N',N'-tetraacetic acid (BAPTA AM, 1-10 microM), a membrane-permeable intracellular Ca2+ chelator. 5. The ionomycin response was not affected by pertussis toxin (PTX, 0.3-2.0 microgram/ml), a blocker of guanine nucleotide-binding regulatory proteins (G proteins). In contrast, the response to acetylcholine (ACh), which is known to occur via a G protein, was suppressed by PTX. 6. The fast component was not affected by removing Ca2+ from the bathing medium or by replacing extracellular Ca2+ with Ba2+ or Mn2+ (all of these solutions were supplemented with 2 mM EGTA), whereas the slow component was suppressed. 7. Injection of inositol 1,4,5-trisphosphate (IP3) following a response to extra-cellularly applied ionomycin did not evoke an appreciable membrane current. In contrast, ionomycin evoked a small inward current when it was applied after an inward-current response evoked by IP3 injection, whereas a second injection of IP3 did not evoke any appreciable current. 8. The results indicate that (a) ionomycin releases Ca2+ from its intracellular stores without the involvement of G proteins, resulting in activation of Ca(2+)-activated Cl- channels, (b) ionomycin mainly acts on the same intracellular Ca2+ stores as IP3, and (c) entry of Ca2+ from outside the cell considerably contributes to the slow component of the ionomycin response, whereas its fast component is predominantly dependent on the release of Ca2+ from the intracellular stores.


Role of bicarbonate in pH recovery from intracellular acidosis in the guinea-pig ventricular myocyte. 1. Intracellular pH (pHi) was recorded ratiometrically in isolated guinea-pig ventricular myocytes using the pH-sensitive fluoroprobe, carboxy-SNARF-1 (carboxy-seminaphthorhodafluor). 2. Following an intracellular acid load (10 mM NH4 Cl removal), pHi recovery in HEPES-buffered Tyrode solution was inhibited by 1.5 mM amiloride (Na(+)-H+ antiport blocker). In the presence of amiloride, switching from HEPES buffer to HCO3-/CO2 (pHo of both solutions = 7.4) stimulated a pHi recovery towards more alkaline levels. 3. Amiloride-resistant, HCO(3-)-dependent pHi recovery was inhibited by removal of external Na+ (replaced by N-methyl-D-glucamine), whereas removal of external Cl- (replaced by glucuronate, leading to depletion of internal Cl-), removal of external K+, or decreasing external Ca2+ by approximately tenfold had no inhibitory effect. These results suggest that the amiloride-resistant recovery is due to a Na(+)-HCO3- cotransport into the cell. 4. The stilbene derivative DIDS (4,4'-diisothiocyanatostilbene-2,2'-disulphonic acid, 500 microM) slowed Na(+)-HCO(3-)-dependent pHi recovery. 5. Intracellular pH increased in Cl(-)-free solution and this increase still occurred in Na(+)-free solution indicating that it is not caused via Na(+)-HCO3- symport and is more likely to be due to Cl- efflux in exchange for HCO3- influx on a sarcolemmal Cl(-)-HCO3- exchanger. The lack of any significant pHi recovery from intracellular acidosis in Na(+)-free solution suggests that this exchanger does not contribute to acid-equivalent extrusion. 6. Possible voltage sensitivity and electrogenicity of the co-transport were examined by using the whole-cell patch clamp technique in combination with SNARF-1 recordings of pHi. Stepping the holding potential from -110 to -40 mV did not affect amiloride-resistant pHi recovery from acidosis. Moreover, following an intracellular acid load, the activation of Na(+)-HCO3- co-influx (by switching from HEPES to HCO3-/CO2 buffer) produced no detectable outward current (outward current would be expected if the coupling of HCO3- with Na+ were > 1.0). 7. Intracellular intrinsic buffering power (beta i) was assessed as a function of pHi (beta i computed from the decrease of pHi following reduction of extracellular NH4 Cl in amiloride-containing solution). beta i in the ventricular myocyte increases roughly linearly with a decrease in pHi according the following equation: beta i = -28(pHi) +222.6. 8. Comparison of acid-equivalent efflux via Na(+)-HCO3- symport and Na(+)-H+ antiport showed that, following an intracellular acidosis, the symport accounts for about 40% of total acid efflux, the other 60% being carried by the antiport.(ABSTRACT TRUNCATED AT 400 WORDS)


Diazoxide blocks glutamate desensitization and prolongs excitatory postsynaptic currents in rat hippocampal neurons. 1. The effects of diazoxide (DZ) on synaptic transmission and upon responses to exogenously applied glutamate agonists were examined in cultured hippocampal neurons. 2. DZ reversibly increased the peak amplitude of evoked excitatory postsynaptic currents (EPSCs) to 150 +/- 100% of control and prolonged the EPSC decay time constant (tau) from 5.9 +/- 1.2 ms to 14 +/- 6.2 ms (240% of control). 3. Peak and steady-state glutamate (Glu) and quisqualate (QA) currents activated by exogenous application were dramatically increased by DZ at concentrations which did not influence N-methyl-D-aspartate (NMDA), kainate (KA), or GABA currents. These effects were rapidly and completely reversible. Active and passive membrane properties were unaffected by DZ. 4. Inhibitory postsynaptic currents (IPSCs) were unaffected by the same DZ concentrations. 5. These experiments indicate that desensitization plays an important role in terminating excitatory transmission between mammalian central neurons. DZ and perhaps related compounds will ultimately help us identify the regions of the AMPA/KA receptor responsible for desensitization.


Three potassium channels in rat posterior pituitary nerve terminals. 1. The patch clamp technique was used to investigate the K+ channels in the membranes of nerve terminals in thin slices prepared from the rat posterior pituitary. 2. Depolarization of the membrane produced a high density of K+ current. With a holding potential of -80 mV, test pulses to +50 mV activated a K+ current which was inactivated by 65% within 200 ms. Hyperpolarizing prepulses enhanced the transient K+ current, with half-maximal enhancement at -87 mV. Depolarizing prepulses reduced or eliminated the transient K+ current. 3. In cell-attached patches formed with pipettes containing 130 mM KCl, three types of K+ channel could be distinguished on the basis of single-channel properties. One channel had a conductance of 33 pS and was inactivated with a time constant of 18 ms. A second channel had a conductance of 134 pS and was inactivated with a time constant of 71 ms. A third channel had a conductance of 27 pS, was activated relatively slowly with a time constant of 65 ms, and was not inactivated during test pulses of up to one second in duration. 4. Inactivation of the whole-cell K+ current was a biphasic process with two exponential components. The fast component had a time constant of 22 ms (at +50 mV), corresponding well with the time constant of decay of average current in cell-attached patches containing only the rapidly inactivating K+ channel. The slow component of inactivation had a time constant of 104 ms (at +50 mV), which was similar to but slightly slower than the time constant of decay of the average current in cell-attached patches containing only the slowly inactivating K+ channel. Inactivation of the slow transient K+ current became more rapid with increasing depolarization. 5. The low-conductance rapidly inactivating K+ channel had a lower voltage threshold for activation than the other two K+ channels. 6. Both inactivating K+ channels were enhanced in a similar manner by prior hyperpolarization. There was no difference with regard to voltage mid-point or steepness. 7. The large-conductance slowly inactivating K+ channel was activated by Ca2+ at the inner membrane surface. The resting intracellular Ca2+ was sufficiently high to produce significant activation of this channel without depolarization-induced Ca2+ entry. 8. Removal of Ca2+ from the bathing solution produced a -10 mV shift in the voltage dependence of enhancement of both transient K+ currents by prior hyperpolarization. This could be explained as a surface charge effect.(ABSTRACT TRUNCATED AT 400 WORDS)


Influence of hypertonic-hyperoncotic solution and furosemide on canine hydrostatic pulmonary oedema resorption. 1. This study aimed at enhancing the clearance of experimental hydrostatic pulmonary oedema in dogs using hypertonic-hyperoncotic solution (HHS) and furosemide. 2. Anaesthetized dogs (n = 20) were mechanically ventilated with a positive end-expiratory pressure of 10 cmH2O (1.0 kPa). 3. Hydrostatic pulmonary oedema was induced by inflating a balloon inserted into the left atrium and simultaneously infusing isotonic saline rapidly. Oedema formation was terminated by deflating the balloon and reducing the infusion rate. 4. Four groups were studied: A, control; B, furosemide; C, HHS and D, HHS+furosemide. HHS, 6 ml kg-1, was given as a bolus injection and furosemide, 1 mg kg-1, intravenously as a bolus followed by an infusion of 0.5 mg kg-1 h-1. All dogs were studied for 4 h. 5. Serum osmolarity, plasma colloid oncotic pressure and diuresis in groups C and D (HHS groups) substantially increased; haemoglobin concentration decreased and pulmonary arterial wedge pressure remained constant. 6. Despite the combination of these factors favouring fluid flux from the extravascular to the intravascular compartment, extravascular lung water measured with the double indicator dilution technique decreased no faster in the HHS groups than in the two other groups (from over 26 to approximately 19 ml kg-1 in groups A, C and D and to 14.7 in group B (only furosemide)). 7. This was confirmed by postmortem gravimetric measurements of extravascular lung water; A, 11.0 +/- 5.7; B, 9.7 +/- 3.3; C, 10.5 +/- 3.1 and D, 10.6 +/- 1.8 g kg-1. 8. We speculate that mechanisms other than effective Starling gradients and enhanced diuresis might define a maximal rate of pulmonary oedema clearance.


The inward rectifier K+ current underlies oscillatory membrane potential behaviour in bovine pigmented ciliary epithelial cells. 1. Fresh bovine, pigmented ciliary epithelial cells possess an inward rectifier current activated by hyperpolarization. This current was investigated using whole-cell patch-clamp techniques. At the holding potential of -70 mV, and with EK (potassium equilibrium potential) set at -84 mV, a small outward current flowed through the inward rectifier that was sensitive to external K+, becoming more outward in 0.5 mM K+ and progressively more inward in 20 and 50 mM K+. 2. The inward rectifier showed V-EK dependence; increasing [K+]o increased the inward conductance from 1.28 nS in 5 mM K+ to 7.42 nS in 50 mM K+. The conductance at a given V-EK was proportional to the square root of [K+]o. 3. It was blocked by external Cs+ but replacing K+ in the pipette with Cs+ blocked only outward ion movement through the inward rectifier. Inward rectification was also blocked by Ba2+ (85% with Ki (concentration giving half-maximal inhibition) = 3.1 x 10(-5) M) and TEA+ (74% with Ki = 2.9 x 10(-4) M). 4. The activation time constant was voltage dependent, decreasing from 5 ms to 0.7 ms over the voltage range -90 to -170 mV. With increasing hyperpolarization the current exhibited time-dependent decay. The time constant for this process was voltage sensitive but the steady-state inactivation was independent of external [K+]. 5. The current disappeared in culture within 8 days. 6. Solution flow over the cell inactivated the inward rectifier, a property that may be related to [K+]o. 7. In current clamp the cells exhibited an unstable region at a potential of around -70 mV. Once in this region oscillations and regenerative hyperpolarizing potentials were observed. This behaviour was eliminated by treatments that blocked (Cs+, Ba2+) or removed (0.5 mM K+) active inward rectification. 8. It is suggested that these oscillations may represent a process of cation loading, the first step in the secretion of aqueous humour.


Inorganic phosphate decreases the Ca2+ content of the sarcoplasmic reticulum in saponin-treated rat cardiac trabeculae. 1. Measurements of [Ca2+] were made in saponin-permeabilized rat ventricular trabeculae using the fluorescent indicator Indo-1. Application of caffeine (20 mM) caused a transient rise in [Ca2+] within the preparation as a result of Ca2+ release from the sarcoplasmic reticulum (SR). The size of the caffeine-induced Ca2+ transient was related to the amount of Ca2+ accumulated by the SR prior to addition of caffeine. Caffeine-induced Ca2+ release was abolished by ryanodine (10 microM), an inhibitor of SR Ca2+ release. 2. At a bathing [Ca2+] of 0.2 microM, the amount of Ca2+ released from the SR on addition of caffeine was sufficient to generate a tension transient. Ca2+ and tension responses were stabilized by application of caffeine at regular intervals (2 min). Addition of 10 mM inorganic phosphate (Pi) induced a transient increase in [Ca2+] within the preparation due to a net release of Ca2+ from the SR. The amplitude of subsequent caffeine-induced Ca2+ transients were reduced to 65 +/- 7.5% (mean +/- S.D., n = 13) of control. In addition, the accompanying tension transient fell to 45 +/- 6.9% of control. Removal of Pi caused a transient decrease in the [Ca2+] within the preparation consistent with a net increase in Ca2+ uptake by the SR. Subsequent caffeine-induced Ca2+ and tension transients returned to control levels. 3. Inclusion of Pi (2-30 mM) in the perfusing solution decreased the size of caffeine-induced Ca2+ and tension transients in a dose-dependent manner. 4. Addition of 10 mM ADP caused a transient increase in [Ca2+] and depressed subsequent caffeine-induced Ca2+ transients to a greater extent than 10 mM Pi. Despite the reduction in Ca2+ release from the SR, tension responses were larger in the presence of 10 mM ADP than under control conditions. This is a consequence of an increase in Ca(2+)-activated force by ADP. 5. A decrease in the amplitude of caffeine-induced Ca2+ transients also occurred on changing from a solution containing 1 mM ADP and 10 mM Pi to a solution with 10 mM ADP and 1 mM Pi. This confirms the previous observation that ADP is more effective than Pi at reducing caffeine-induced Ca2+ released from the SR. 6. Spontaneous oscillations of [Ca2+] and tension occurred in the presence of 0.5 microM Ca2+.(ABSTRACT TRUNCATED AT 400 WORDS)


Adaptation of quantal content to decreased postsynaptic sensitivity at single endplates in alpha-bungarotoxin-treated rats. 1. Rats were injected once every 48 h with alpha-bungarotoxin (alpha BTX) for periods up to 6 weeks. Injections caused weakness of facial muscles which lasted about 8 h. Hemidiaphragms were dissected for biochemical and electrophysiological measurements. 2. In muscles from animals treated for 2-3 weeks with toxin, the binding of 125I-alpha BTX was reduced to 58%, and the ACh content to 81% of control values. Choline acetyltransferase activity was unchanged. ACh release evoked by 3 Hz nerve stimulation was increased to 175% of control values. 3. The use of mu-conotoxin, which specifically blocks muscle action potentials, enabled the recording of full-sized endplate potentials (EPPs) and miniature endplate potentials (MEPPs) at normal muscle membrane potentials (-70 to -80 mV). The amplitude of MEPPs was decreased to 57% in muscles from animals treated for 3 weeks with alpha BTX. The mean of the quantal contents, calculated from the ratio of the corrected EPPs and the MEPPs, was increased to 154%. 4. Within individual muscles of both alpha BTX-treated and control rats, there was an inverse relationship between the quantal content of an endplate and its MEPP amplitude. 5. The MEPP frequency of endplates from control muscles was positively correlated with the quantal content. However, this correlation was not found in alpha BTX-affected muscles. 6. Three hours after a single injection of alpha BTX the amplitude of the MEPPs was reduced to about 60% of control values but no increase of the quantal content was found. During the first few days of alpha BTX treatment the quantal content gradually increased; it reached a plateau between 20 and 30 days. 7. The results suggest the existence of an adaptive mechanism, operating at individual endplates, in which retrograde signals at the motor nerve terminals modulate ACh release when neuromuscular transmission is endangered by block of acetylcholine receptors.


Discharge characteristics and rapid resetting of autoactive aortic baroreceptors in rats. 1. An in vitro aortic arch-aortic nerve preparation was used to characterize the pressure-discharge properties of aortic 'autoactive' baroreceptors (aBRs), a functionally unique group of baroreceptors that discharge continuously below pressure threshold (Pth). These units contrast to more familiar 'quiescent' BRs (qBRs) that are silent below Pth. This study also examined whether aBRs rapidly reset to sustained changes in mean arterial pressure (MAP), and whether they respond to local vasoconstriction, as found in qBRs. 2. Pressure-discharge curves were constructed using slow pressure ramps (2 mmHg s-1) in a total of fifty-four aBRs and sixty-four qBRs from fifty-three Wistar-Kyoto rats. Rapid resetting was tested by comparing the curves before and 15 min after adjusting MAP to selected levels between 40 and 180 mmHg. Response curves were also compared before and after constricting the arch with 10(-8) M angiotensin II. 3. Compared to qBRs, aBRs had significantly lower Pth values (83 +/- 2 versus 91 +/- 2 mmHg, mean +/- S.E.M., P < 0.05) but similar threshold frequencies (13 +/- 1 versus 16 +/- 2 Hz), higher saturation pressures (138 +/- 4 versus 123 +/- 2 mmHg) but similar saturation frequencies (55 +/- 3 versus 55 +/- 3 Hz), and lower suprathreshold sensitivities (slope of linear region: 1.1 +/- 0.1 versus 1.4 +/- 0.1 Hz mmHg-1) but wider operating ranges (57 +/- 4 versus 35 +/- 3 mmHg). 4. The aBRs rapidly reset to changes in MAP (n = 16), and the extent of resetting (delta Pth/delta MAP = 0.26) was similar to that in qBRs (0.23). 5. Vasoconstriction had no effect on aBR subthreshold discharge (n = 5), but inhibited suprathreshold responses to pressure much like that in qBRs. 6. These results suggest that aortic aBRs may extend the range of the baroreflex, but probably do not improve its sensitivity to transient fluctuations in pressure or its ability to correct changes in mean pressure over extended periods. 7. Subthreshold discharge in aBRs appears to be an intrinsic property of these units, which was not affected by resetting or changes in vascular tone. At suprathreshold pressures, contraction of local smooth muscle modulates the aBRs and qBRs in a similar fashion by mechanically unloading the sensory endings.


Comparison of skeleto-fusimotor innervation in cat peroneus brevis and peroneus tertius muscles. 1. The skeleto-fusimotor or beta innervation was compared in cat peroneus brevis and peroneus tertius muscles, which differ in their composition of fatigue-resistant motor units; the slow (S) units predominate in brevis and the fast units (FR) in tertius. 2. In four brevis muscles, of thirty-four beta-axons (from a total of 114 axons supplying extrafusal muscle fibres) twenty-nine were dynamic (beta D) and only five static (beta S). In contrast, in three tertius muscles, of twenty-five beta-axons (from a total of 82 axons) twelve were static and thirteen dynamic. 3. In a population of thirty-five brevis and thirty tertius spindles, the proportion of beta D-innervated spindles was greater in the brevis (68.5%) than in the tertius (50%) whereas that of beta S-innervated spindles was greater in the tertius (40%) than in the brevis (17.1%). In a population of thirty-two brevis and twenty-seven tertius spindles in which the presence of bag1 fibres was deduced from the existence of a dynamic innervation, the proportion of spindles innervated by beta D-axons was 80% in the brevis and 62% in the tertius. 4. In both muscles, the number of beta D effects was greater than that of beta S effects. beta S-axons were rarely found to supply more than one spindle whereas beta D-axons supplying more than one spindle (up to four) were common. Spindles were often coinnervated by beta D- and beta S-axons.(ABSTRACT TRUNCATED AT 250 WORDS)


A physiological study of vestibular and prepositus hypoglossi neurones projecting to the abducens nucleus in the alert cat. 1. Vestibular and prepositus hypoglossi (PH) neurones projecting to the abducens (ABD) nucleus were recorded in the alert cat. Their discharge characteristics were analysed to ascertain the origin of the horizontal eye position signal present in ABD neurones. 2. Neurones were classified according to: their location with respect to the ABD nucleus; their antidromic activation from the ABD nucleus; the synaptic field potential they induced in the ABD nucleus with the spike-triggered averaging technique; and their activity during spontaneous and vestibularly induced eye movements. 3. Vestibular neurones projecting to the ABD nucleus were located in the rostral medial vestibular nucleus. They were excitatory on the contralateral and inhibitory on the ipsilateral ABD neurones. Both types of premotor vestibular neurone showed a firing rate weakly related to eye position, increasing for eye fixations in the contralateral on-direction, and decreasing with ipsilateral fixation. Position sensitivity during eye fixations was (means +/- S.D.) 1.8 +/- 0.9 spikes s-1 deg-1 for excitatory neurones and 2.2 +/- 1.3 spikes s-1 deg-1 for inhibitory neurones. Firing rate exhibited a high variability during eye fixations. Their responses during saccades in the off-direction were characterized by a pause that, although less defined, was occasionally present during saccades in the on-direction. Eye velocity sensitivity during spontaneous saccades in the on-direction was 0.17 +/- 0.15 spikes s-1 deg-1 s-1 for excitatory neurones and 0.15 +/- 0.07 spikes s-1 deg-1 s-1 for inhibitory vestibular neurones. During sinusoidal head stimulation at 0.2 Hz, vestibular neurones showed a type I discharge rate with a phase lead over eye position of 86.0 +/- 14.1 deg for excitatory and 80.2 +/- 12.5 deg for inhibitory neurones. Position sensitivity during vestibular stimulation did not differ significantly from values obtained for spontaneous eye movements. However, the velocity sensitivity of premotor vestibular neurones during head rotation was significantly higher (1.6 +/- 0.2 spikes s-1 deg-1 s-1 for excitatory and 1.5 +/- 0.3 spikes s-1 deg-1 s-1 for inhibitory neurones) than during spontaneous eye movements. 4. PH neurones projecting to the ABD nucleus were located in the rostral one-third of the nucleus. These neurones were excitatory on the ipsilateral and inhibitory on the contralateral ABD nucleus. Their firing rates were correlated mainly with eye position, increasing for abducting eye positions of the ipsilateral eye and decreasing with adduction movements.(ABSTRACT TRUNCATED AT 400 WORDS)


Effects of vasopressin and angiotensin II on neurones in the rat dorsal motor nucleus of the vagus, in vitro. 1. Extracellular recordings were made from 297 spontaneously firing neurones in the dorsal motor nucleus of the vagus (DMV) in slice preparations of rat medulla oblongata. Some of the neurones recorded were identified to be vagal motoneurones by antidromic stimulation. The cells fired with a slow irregular pattern at an average rate of 1.1 +/- 0.1 spikes/s (mean +/- S.E.M.). 2. Arginine vasopressin (AVP) was applied by perfusion in 196 of the 297 cells. Most of the neurones (190/196, 97%) were excited by 10(-6) M AVP with an increase in firing rate from the basal level of 1.1 +/- 0.1 to a maximum of 2.5 +/- 0.2 spikes/s. There was a dose-dependent relation between the concentration of AVP and the increased firing rate in all DMV neurones tested (n = 38). The threshold concentration of the peptide to produce changes in firing rate was assumed to be about 10(-10) M. The remaining six neurones were not affected by application of AVP. 3. Application of oxytocin (OXT, 10(-6) M) increased the firing rate of all thirty-eight neurones tested. The effects of AVP and OXT on all neurones examined (n = 20 and 4, respectively) still persisted after blocking the synaptic transmission in a low-Ca2+ or Ca(2+)-free-high-Mg2+ solution, indicating the direct action of both AVP and OXT on the postsynaptic membranes. 4. The AVP-induced excitatory responses were completely but reversibly blocked by the V1-type receptor antagonists, [1-(beta-mercapto-beta, beta-cyclopentamethylene-propionic acid), 2-(O-methyl)tyrosine]-arginine vasopressin (d(CH2)5Tyr(Me)AVP) (n = 5) and Phaa-D-Tyr(Et)Phe-Gln-Asn-Lys-Pro-Arg-NH2 (n = 6), whereas a selective and reversible OXT receptor antagonist, desGly-NH2d(CH2)5[Tyr-(Me)2Thr4]ornithine vasotocin, which suppressed the OXT-induced excitation, did not block the responses to AVP (n = 11). 5. Application of angiotensin II (AII, 10(-6) M) to 153 neurones increased the firing rates of 60 (39%) neurones. The firing rate was increased from the basal level of 1.0 +/- 0.1 to a maximum of 1.8 +/- 0.2 spikes/s (n = 60). The effect of AII was completely abolished by an AII receptor antagonist, [Sar1,Ile8]angiotensin II (n = 6). There was a dose dependence of the excitatory response on AII concentration in all of eleven neurones tested. The threshold concentration was assumed to be about 10(-9) M. The activity of 5 (3%) of 153 neurones was decreased, and the remaining 88 (58%) neurones were not affected by AII.(ABSTRACT TRUNCATED AT 400 WORDS)


Responses of macaque ganglion cells to movement of chromatic borders. 1. We have measured responses of macaque ganglion cells to moving borders under conditions designed to simulate the minimally distinct border (MDB) task. 2. Extending previous results, we show that minimization of responses of phasic ganglion cells of the magnocellular (MC)-pathway obey the photometric laws of transitivity and additivity. 3. To equal luminance borders, a residual response was present in MC-pathway cells analogous to the second harmonic response seen in these neurones with temporal chromatic modulation. It was proportional to the tritanopic purity difference (magnitude of delta Pt, the rectified middle- to long-wavelength cone opponent signal) between the two colours on either side of the border. For a delta Pt of one, the mean residual response was equivalent to the response evoked by achromatic borders of about 14% luminance contrast. Both these properties of the MC-pathway closely resemble psychophysical estimates as to the distinctness of equal luminance borders. 4. We show how MC-pathway cell responses could be used centrally to support the MDB task. It was difficult to generate a model from responses of tonic ganglion cells of the parvocellular (PC)-pathway which would support the task. 5. The MDB task is still possible psychophysically after blurring the retinal image. Although blurring the border spatially smeared the responses of MC-pathway ganglion cells and reduced their amplitude, responses still went through a minimum close to equal luminance. Thus, blurring the image did not affect the ability of MC-pathway cells to support the task. Blurring the retinal image decreased the 'sharpness' of the border response of tonic, PC-pathway ganglion cells, but response amplitude was unaffected. Response features indicative of centre-surround organization were attenuated. A central mechanism reliant on centre-surround field structure of PC-pathway cells would thus not be able to support the task after blurring. 6. Taken together, these results strongly suggest that the MC-pathway forms the sole physiological substrate of the MDB task, and any contribution of the PC-pathway is, indeed, minimal.


Depolarizing action of cholecystokinin on rat supraoptic neurones in vitro. 1. Cholecystokinin is co-localized within the oxytocin- and, to a lesser extent, vasopressin-synthesizing magnocellular neurones in the hypothalamic supraoptic and paraventricular nuclei. These nuclei are also prominent binding sites for cholecystokinin. In the present study we used intracellular current- and voltage-clamp recordings from fifty-seven supraoptic nucleus cells, maintained in superfused explants of rat hypothalamus, to assess their membrane responses to exogenous cholecystokinin and define the nature of their cholecystokinin receptors. 2. In a majority of the fifty-seven cells tested, bolus infusions into the superfusion media of cholecystokinin fragments (maximum concentrations estimated at 0.3-15 microM) were followed within 1-5 s by a transient and reversible membrane depolarization. Active peptides included sulphated cholecystokinin octapeptide (26-33) (28 of 33 cells responded), non-sulphated cholecystokinin octapeptide (26-33) (21 of 25 cells responded), cholecystokinin tetrapeptide (30-33) (20 of 24 cells responded and caerulein (4 of 4 cells responded). None of five cells responded to cholecystokinin (26-28). Depolarizing responses to cholecystokinin analogues persisted in the presence of tetrodotoxin (0.2-0.4 microM), and in Ca(2+)-free solutions containing MnCl2 (2.5 mM). 3. Under voltage clamp, cholecystokinin fragments evoked an inward current accompanied by an increase in membrane conductance. The amplitude of the inward current varied linearly as a function of membrane voltage, with an extrapolated reversal potential of approximately -15 mV. Reversal potentials were not altered by chloride injection. These features suggest that cholecystokinin activates a non-selective cationic conductance. 4. Active cholecystokinin analogues were approximately equipotent in their depolarizing actions, a feature that supports the activation of cholecystokinin-B type receptors. Moreover bath application of 200 nM L-365,260, an antagonist with a high affinity for cholecystokinin-B receptors, reversibly attenuated the cholecystokinin-induced responses in four of six cells tested. 5. These observations indicate that cholecystokinin can directly influence the excitability of rat supraoptic nucleus neurones and provide evidence for an additional site where this peptide may act within the hypothalamo-neurohypophysial axis.


NMDA receptor-mediated rhythmic bursting activity in rat supraoptic nucleus neurones in vitro. 1. Intracellular recordings were obtained from 112 supraoptic nucleus magnocellular neurosecretory cells (MNCs) in superfused explants of rat hypothalamus maintained in vitro. The effects of glutamate receptor agonists and antagonists were examined at 32-34 degrees C. 2. In control solutions, spontaneously active (> 5 Hz) phasic or continuous neurones showed interspike interval distributions slightly skewed toward short intervals, but did not feature pauses in the 0.4-2 s range. Current injection to alter the rate of cell discharge shifted the histograms according to the mean firing rate, but failed to induce intermittent pauses in the 0.4-2 s range. 3. Application of N-methyl-D-aspartate (NMDA) induced a mode of firing in which bimodal interspike interval distributions reflected a high incidence of clusters of short interspike intervals (0.5-1.5 s) recurring every 1-3 s. In contrast, firing evoked by application of D,L-alpha-amino-3-hydroxy-5-methyl-4-isoxalone propionic acid (AMPA) was not associated with a clustering of impulse discharge. 4. The putative endogenous excitatory amino acid transmitters L-glutamate, L-aspartate and quinolinate all mimicked the effects of NMDA. Clustered spiking responses to these agents were reversibly blocked by D,L-2-amino-5-phosphono-valerate (APV), but not by 6-cyano-7-nitroquinoxaline-2,3-dione (CNQX). In contrast, the non-NMDA receptor ligands kainate and quisqualate caused CNQX-sensitive increases in firing rate, but these responses were not associated with the appearance of clustered activity. 5. When applied to cells showing negative resting potentials (< -70 mV), or to neurones hyperpolarized by current injection, responses to NMDA consisted of rhythmic (approximately 1 Hz) voltage oscillations associated with bursts of spike discharge. In the presence of TTX, NMDA could induce subthreshold voltage oscillations in the absence of action potentials. 6. Application of a voltage clamp to potentials between -75 and -55 mV during rhythmic bursting responses failed to reveal any rhythmic oscillation of the membrane current. In all cases, rhythmic bursting activity resumed upon returning to the current-clamp mode. 7. Rhythmic bursting responses to NMDA application were abolished in Mg(2+)-free solutions, suggesting that the voltage dependence of NMDA channels served to promote regenerative voltage changes throughout the cycle. The NMDA-induced current itself, however, did not appear to decrease with time, suggesting that a distinct, outward current, was necessary to initiate the repolarizing phase of each cycle.(ABSTRACT TRUNCATED AT 400 WORDS)