Effect of splenectomy on the immune response of BALB/c mice bearing an immunoglobulin M plasmacytoma (TEPC-183).

Mice bearing TEPC-183, an immunoglobulin M(kappa)-secreting plasmacytoma, exhibit severe suppression of their immune responses to both thymus-dependent and thymus-independent antigens, 2,4-dinitrophenyl, and the type 3 pneumococcal polysaccharide SSS-III. This immunosuppression is not lifted by splenectomy of the tumor-bearing mice or prevented by removal of the spleen prior to tumor injection. On the contrary, splenectomy either before or after tumor implantation further accentuates the immunosuppressed state of tumor bearers and even depresses the immune response of normal mice. A secondary immune response of normal mice 34 to 51 days after splenectomy is still reduced. Thus, spleen cells may play a dual role. While splenectomy may remove a source of suppressor cells in tumor-bearing mice, it also eliminates a major source of antibody-producing cells and results in reduced immune responses of normal and TEPC-183-bearing mice. These findings have clinical relevance since splenectomy is used as a therapeutic and diagnostic procedure in neoplastic lymphoproliferative disorders.


Bypassing the "species barrier" with carbohydrate-altered interferon from leukocytes.

Interferon, a glycoprotein with demonstrated antitumor and antiviral properties, can be obtained from cells of different species, and some of these interferons can be effective across species lines. I hypothesize that the ability to cross or not to cross species lines lies in the carbohydrate moiety, and cross-species biological activity is a property of the polypeptide. This would represent one of the first major roles uncovered for glycosylation in any biological system. If this hypothesis is correct, then it should be possible to use animal-derived interferon as a large scale, inexpensive source to treat human diseases.


Multiple myeloma resistant to melphalan: treatment with cyclophosphamide, prednisone, and BCNU.

Eighty-nine patients with multiple myeloma resistant to melphalan were randomized to receive cyclophosphamide plus prednisone (CP) (47 patients) or cyclophosphamide plus BCNU plus prednisone (CBP) (42 patients). No differences were detected in the two groups prior to therapy. Objective responses occurred in three (7%) of the CP patients and in seven (17%) of the CBP patients. About 40% of the patients in each group achieved some response. Toxic reactions consisted mainly of leukopenia and thrombocytopenia. Median survival was not different in the two groups. The median survival time was 31 months among those patients with an objective response and 9.4 months among those without an objective response. The addition of BCNU to CP increased the frequency of objective response, but not significantly. This triple combination (CBP) cannot be recommended.


Association between steroid hormone receptor status and disease-free interval in breast cancer.

The possibility of an association between steroid hormone receptor status and disease-free interval was examined in 292 patients with breast cancer. Estrogen receptor positivity was associated with a prolonged disease-free interval. This association was independent of age, menopausal status, tumor size, or nodal status. There was no association between the presence or absence of progesterone, androgen, or glucocorticoid receptor and disease-free interval.


Mechanisms of sensitivity or resistance of murine tumors to N-(phosphonacetyl)-L-aspartate (PALA).

Several biochemical parameters were examined relative to the sensitivity or resistance of representative rodent tumors to N-(phosphonacetyl)-L-aspartate (PALA). The activity of the target enzyme, L-aspartate transcarbamylase (ATCase), was evaluated in homogenates of a spectrum of murine neoplasms. ATCase activity was significantly lower in PALA-sensitive as opposed to PALA-refractory tumors. However, among tumors sensitive to PALA, there was no clearcut relationship between ATCase activity and degree of sensitivity to PALA. Thus, a number of hypotheses were proposed to explain differential sensitivity to PALA in vivo. Enzyme activities in the salvage pathway which phosphorylate pyrimidine nucleosides and deoxynucleosides were found to be greater in refractory tumors. The uptake of PALA, in vitro, though quite slow, was found to be two to eight times greater in two sensitive tumors as compared to the refractory L1210 leukemia. However, in vivo, 24 hours following graduated doses of PALA, nearly identical intratumoral drug concentrations were observed in representative sensitive and refractory tumors. Thus, ultimately, PALA transport would not appear to correlate with differences in drug sensitivity. A number of other biochemical parameters were also found to have no association with sensitivity to PALA in vivo. These included: kinetics of inhibition of ATCase, capacity for restitution of ATCase activity after a dose of PALA, degree of inhibition of ATCase at various doses of PALA, detoxification of PALA by tumor cells, kinetics of uptake of uridine, or catabolism of pyrimidines or pyrimidine nucleosides.


Role of plasma carcinoembryonic antigen in evaluating patients with breast cancer treated with adjuvant chemotherapy.

Serial plasma carcinoembryonic antigen (CEA) levels were determined in 84 patients with breast cancer who were receiving postsurgical adjuvant chemoimmunotherapy or adjuvant chemotherapy. CEA values were correlated with clinical status, scintiscans, alkaline phosphatase, LDH, and SGOT. CEA values greater than 2.5 ng/ml were considered abnormal. Thirty patients had normal serial CEA values; all remain disease-free. In 54 patients one or more abnormal CEA values were recorded; nine of 54 developed overt metastatic disease. Relapses occurred in four of 38 patients in whom values up to 5 ng/ml were recorded, in three of 14 patients in whom values up to 10 ng/ml were recorded, and in two of two patients in whom values greater than 10 ng/ml were recorded.


Phase II trial of piperazinedione in malignant melanoma: a report by the Southeastern Cancer Study Group.

Forty-one evaluable patients with malignant melanoma resistant to other chemotherapeutic agents received 9 mg/m2 of piperazinedione every 3 weeks. Two patients had partial responses and one additional patient had stable disease. One of the partial responses occurred in a patient with subcutaneous metastases and the other occurred in a patient with pulmonary and osseous metastases. Both antitumor responses occurred in the 17 patients with a performance status of greater than or equal to 80%. The dose-limiting toxicity was myelosuppression; thrombocytopenia was more frequently observed than granulocytopenia.


Phase II study demonstrating failure of both a five-drug continuous-therapy regimen and a two-drug pulse-therapy regimen in the treatment of metastatic neuroblastoma: Southwest Oncology Group Study 822.

Twenty-six children greater than 1 year of age with previously untreated stage IV neuroblastoma were randomized to receive either a five-drug regimen (prednisone, cyclophosphamide, actinomycin D, vincristine, and daunorubicin) or a two-drug regimen (cyclophosphamide and vincristine). Complete response rates were 6% and 9% for the five-drug and the two-drug regimens respectively. Partial response rates were 13% and 27% for the five-drug and the two-drug regimens respectively. The mean duration of the seven responses was 9 months, and all 26 patients had died within 2 years. Neither regimen was effective for long-term disease control in these children with neuroblastoma.


Phase II evaluation of diglycoaldehyde, VP-16-213, and the combination of methyl-CCNU and beta-2'-deoxythioguanosine in previously treated patients with colorectal cancer: an Eastern Cooperative Oncology Group study (EST-1275).

The Eastern Cooperative Oncology Group assessed the activity of diglycoaldehyde (DGA), VP-16-213, and the combination of methyl-CCNU and beta-2'-deoxythioguanosine in previously treated patients with advanced colorectal cancer. Objective responses were seen in two of 40 evaluable patients receiving methyl-CCNU and beta-2'-deoxythioguanosine and in one of 35 patients receiving DGA. None of 33 patients responded to VP-16-213, but one death related to sepsis and bone marrow failure occurred. Survival of patients whose previous chemotherapy included a nitrosourea was markedly shortened compared to those who had not been exposed to nitrosoureas. With the possible exception of DGA, further treatment of patients with colorectal cancer with these therapies is not warranted.


ICRF-159 (razoxane) in the treatment of pediatric solid tumors: a Southwest Oncology Group study.

ICRF-159 is active in several animal tumor model systems and human adult malignancies. In this phase II study, ICRF-159 was given on a weekly schedule, 3000 mg/m2/day, orally in three divided doses at 6-hour intervals to 78 children with a variety of malignant neoplasms. Fifty-three patients were evaluable for tumor response. Toxicity was primarily hematopoietic and gastrointestinal. There were no responses in any of the eight patients with osteogenic sarcoma, four with lymphoma, five with Ewing's sarcoma, ten with neuroblastoma, or six with rhabdomyosarcoma. There was a transient partial response in one of four children with Wilms' tumor. Further trials with this drug using this schedule are not indicated for the common childhood solid tumors.


Combination chemotherapy for extracranial metastases of a primary malignant cerebral neoplasm.

A patient with a mixed malignant glioma metastatic to the bones and lungs failed to respond to two different broad-spectrum combination chemotherapy regimens which included Adriamycin, methotrexate, cyclophosphamide, CCNU and cis-dichlorodiammineplatinum(II).


Structural investigations of the lipopolysaccharide isolated from Vibrio cholera, Inaba 569 B.

On hydrolysis, the purified lipopolysaccharide (LPS) isolated from Vibrio cholera, Inaba 569 B, yielded glucose, mannose, a heptose behaving like D-glycero-L-manno-heptose and one behaving like D-glycero-L-gluco-heptose, 2-amino-2-deoxyglucose, and glucuronic acid in the molar ratios of approximately 9:4:5:1:2:5. Studies on the LPS, the polysaccharide (PS), and carboxyl-reduced LPS showed that the PS has a branched structure, with (1 leads to 2)-linked mannopyranosyl and a heptopyranosyl, and (1 leads to 4)-linked glucopyranosyluronic and 2-amino-2-deoxyglucopyranosyl residues in the interior part of the molecule, and glucopyranosyl and heptopyranosyl residues as nonreducing end-groups.


An alternative synthesis of 4-deoxy-4-fluoro-D-glucose and its transport in the human erythrocyte.

Treatment of methyl 4-O-mesy-alpha-D-galactopyranoside with benzyl bromide in N,N-dimethylformamide in the presence of silver oxide yielded methyl 2,3,6-tri-O-benzyl-4-O-mesyl-alpha-D-galactopyranoside which with tert-butylammonium fluoride at reflux underwent nucleophilic displacement to give methyl 2,3,6-tri-O-benzyl-4-deoxy-4-fluoro-alpha-D-glucopyranoside. This compound on hydrogenolysis provided crystalline methyl 4-deoxy-4-fluoro-alpha-D-glucopyranoside (9). The structure of 9 was established by its conversion to the 2,3,6-tri-O-acetyl derivative and by n.m.r. and m.s. analysis. Acid hydrolysis of 9 gave 4-deoxy-4-fluoro-D-glucose (1). A modification of an established synthesis of 4-deoxy-D-xylo-hexose (2) from methyl 2,3,6-tri-O-benzoyl-alpha-D-galactopyranoside is described. A systematic comparison was made of the transport parameters (Kx and Vmax) of D-glucose, 2, and 1 in human erythrocytes. The Kx values observed for the above sugars are: 4.0mM, 4.5mM, and 4.6mM, respectively. These results indicate that O-4 in beta-D-glucopyranose is not involved in hydrogen bonding to the carrier protein associated with the transport of D-glucose in the erythrocyte.


The structure of the capsular polysaccharide of Klebsiella K-type 31.

The structure of the Klebsiella K31 capsular polysaccharide has been elucidated by periodate oxidation, methylation analysis, characterization of oligosaccharides obtained by partial, acid hydrolysis, and proton magnetic resonance. The polymer consists of pentasaccharide repeating-units having the following structure (1).


Protection of sodium dodecyl sulfate-induced aggregation of concanalvalin A by saccharide ligands.

Concanavalin A is visibly aggregated by low concentrations of sodium dodecyl sulfate, maximum aggregation being obtained at pH 4.6. Other denaturants, such as urea, guanidine hydrochloride, Triton X-100, cetyltrimethylammonium bromide, Tween 80, and Brij 35 are ineffective in promoting visible aggregation. The sodium dodecyl sulfate-induced aggregation of concanavalin A requires the presence of an intact, saccharide-ligand binding-site. Rapid and complete reversal of the detergent effect was achieved by use of saccharides which bind to the lectin. Such compounds as tryptophan and o-nitrophenyl beta-D-galactopyranoside did not inhibit the aggregation of concanavalin A by sodium dodecyl sulfate, suggesting that the detergent does not bind the hydrophobic pocket on the surface of the protein. The results suggest that concanavalin A may have an additional, ligand-binding site which is metal-dependent and which can be modified by the addition of a saccharide ligand.


The binding of aromatic derivatives of beta-D-galactopyranosides to the FAB' of immunoglobulin J539. Observations on the nature of ligand-antibody interactions.

A number of D-galactopyranosides bearing aromatic substituents have been prepared, and their binding to immunoglobulin J539 (Fab') has been studied. It appears that the main contribution of the 6-O-aromatic moiety to binding arises from the fact that it imparts an increased hydrophobicity to the ligand, causing a decrease in its hydration (solubility) that results in a greater free-energy of binding. In the D-galactosides having an aromatic aglycon, the phenyl group appears to partake in actual interactions with the protein.


Improved purification procedure for the extracellular D-glucosyltransferase from Streptococcus mutans 6715.

The exocellular D-glucosyltransferase from Streptococcus mutans 6715 has been highly purified with minimal loss of enzymic activity. The organisms were cultured in trypticase soy-broth that had been treated with invertase and filtered through an ultrafilter fitted with a membrane having a cut-off molecular weight at 10,000. To the growth medium was added Tween 80, which prevented the enzyme from aggregating. The final step in the purification employed insoluble, streptococcal dextran as an affinity support. Two D-glucosyltransferase activities were detected, viz., one that did not adsorb to the insoluble dextran and one that did. The enzymic fraction that had adsorbed to the insoluble dextran in the affinity column was strongly inhibited by added insoluble dextran.


Vascular hemodynamics: deep rooted misconceptions misnomers.

Erroneous concepts about vascular hemodynamics are widespread, notably as regards the effect of gravity on blood flow. Vascular pressure at any point is equal to the sum of two pressures of entirely different origins: (1) pressure caused by the pumping action of the heart ('cardiodynamic' pressure which is vital for circulation) and (2) pressure due to gravity acting on the blood ('gravitational' or hydrostatic pressure which plays no direct role in blood flow). Gravity neither helps nor hinders circulation because of the U tube or siphon principle. The gravitational energy of the column of blood in arteries is balanced exactly by the gravitational energy of the column in veins and vice versa. Thus, contrary to common belief, gravity does not hinder blood flow to the head in the upright position, nor does it hinder venous return from the dependent parts of the body. For this reason, in Poiseuille's equation, perfusion pressure should exclude gravitational pressure. Postural effects on circulation result from the distension vessels (particulary veins) subsequent to changes in gravitational pressure of blood.


Complete atrio-ventricular block due to cardiac echinococcosis.

A 33-year-old man presented a complete antrio-ventricular block due to two hydatid cysts localized in the interventricular septum and interrupting both bundle branches. Intracardiac rupture within the right ventricle led to extensive pulmonary hydatidosis and death.


Differences in atrial septal activation with an intrasinoatrial nodal pacemaker and epicardial sinoatrial nodal pacing.

Changes in Intra-SA nodal pacemaker localization were produced through stimulation of the decentralized cervical vagi and stellate ganglia in the anesthetized dog. Shifts in pacemaker to the rostral, middle, or caudal regions of the SA node produced a change in the timing as well as a change in the sequence of activation of recording sites overlying the AV node. Epicardial pacing with a plaque electrode from either the rostral, middle, or caudal regions of the SA node produced the same activation sequence of the AV nodal electrodes irrespective of the epicardial SA nodal pacing site. The inability of epicardial SA nodal pacing to precisely reproduce the activation pattern of the atrial septum overlying the AV node observed with a natural SA nodal pacemaker can be explained by the geographic relationship of the pacemaker cells within the node to the preferential internodal pathways and the area of atrial tissue stimulated by pacing. Pacing activates a large mass of tissue, whereas an intrinsic pacemaker probably acts as a more localized focus. The inability of pacing to reproduce the activation pattern seen with spontaneous rhythm may be a determinant in the varied P wave morphology seen with coronary sinus or AV nodal junctional rhythms, as compared with more consistent morphology seen with pacing.


Familial Ebstein's anomaly.

2 adult siblings with Ebstein's anomaly are presented in this report. The second sibling was found to have the anomaly 20 years after the first sibling was diagnosed. The use of echocardiography in screening for Ebstein's anomaly and the diagnostic features are emphasized. Documentation by electrode catheter recording intracardiac electrocardiogram and pressures in the right heart were made.


Effect of a physical conditioning program upon left ventricular ejection fractions determined serially by a noninvasive technique.

6 clinically normal subjects underwent a 3-month physical conditioning program with the ejection fractions determined before and after physical conditioning using a scintillation probe. All subjects achieved a conditioning effect as evidenced by increased treadmill test duration after conditioning (mean duration before conditioning: 658 vs. 715 sec after conditioning; p less than 0.02). All 6 subjects increased resting ejection fractions after conditioning (mean ejection fraction before conditioning: 54.5 +/- 5.4%; mean ejection fraction after conditioning: 67.0 +/- 9.0%; p less than 0.01). Thus, an aerobic physical conditioning program appears to increase resting ejection fractions in normal subjects.


Beneficial effects of ibuprofen in acute myocardial ischemia.

Ibuprofen, a nonsteriodal anti-inflammatory agent, was studied in the early stages of myocardial ischemia in order to determine whether it helps preserve myocardial integrity. Ibuprofen was administered intravenously at a dose of 12.5 mg/kg at the time of coronary artery occlusion and again 2.5 h later. Ibuprofen significantly prevented the loss of myocardial creatine phosphokinase (CPK) release in ischemic cardiac tissue. In addition, this drug significantly returned S-T segment elevation toward normal values, and significantly prevented the myocardial loss of compounds having free amino nitrogen groups, an index of proteolysis. Although ibuprofen moderated the increased plasma CPK activity, plasma CPK values 5 h after coronary occlusion were above control values. Thus, ibuprofen significantly prevented alterations in three of the four indices used to assess myocardial ischemic damage. The protective mechanism of ibuprofen may be via stabilization of cellular membranes (i.e., lysosomal membranes) and to a lesser extent on reduction in myocardial oxygen demand.


Incidence and prognostic significance of intraventricular block in acute myocardial infarction.

In 404 consecutively admitted patients with their first myocardial infarction (MI), intraventricular block (IV) was a complication in 124 (31%). The following types of block were encountered: 21 (5%) had left bundle-branch block (LBBB), 73 (18%) left anterior hemiblock (LAH), 13 (3%) left posterior hemiblock (LPH); 7 (2%) right bundle-branch block (RBBB); 9 (2%) RBBB + LAH, and 1 (0.3%) RBBB + LPH. Patients with IV block at the time of admission did not develop total atrioventricular block more frequently in the acute phase of MI (0-30 days) or in the follow-up period (3-5 years) than patients without IV block. During the acute phase, only patients with RBBB with or without hemiblock showed significantly higher mortality than patients without IV blocks. The other types of IV block did not influence the short-term prognosis. Among patients who survived the acute phase, significantly lower long-term survival rates were found in patients with LBBB compared to patients without IV block, whereas the presence of LAH did not affect the long-term prognosis.


Sudden coronary death and coronary artery disease. A clinicopathologic appraisal.

Clinicopathologic and epidemiological aspects of coronary artery disease (CAD) in relation to sudden death (SD) were studied in three postmortem series, two of sudden cardiac death and one of male violent death. There appears to be a critical level of severity of CAD which determines the risk of SD. The more severe the CAD within this range, the higher is the risk. Every annual cohort of SDs includes many patients with extremely severe, or 'burned-out', disease. CAD alone, however, is not a selective factor for sudden or not-sudden death. Epidemiological analysis (a) determines the age and frequency of persons reaching the critical risk level of CAD severity in the population (atherogenic factors); (b) influences the selection of the SD victims from the critical population (precipitating factors), and (c) determines the individual variation of CAD severity with which coronary heart disease and SD manifest themselves (sensitising and protecting factors).


Bifascicular block produced by hyperkalemia.

Bifascicular block is an unusual manifestation of hyperkalemia. A patient who developed right bundle branch block and left anterior hemiblock as the result of elevated serum potassium concentration is reported. After correction of his hyperkalemia, atrial fibrillation with a rapid ventricular response occurred. There was normal ventricular conduction despite this rate-related stress to his conduction system.


Reversibility of alcoholic cardiomyopathy with abstention from alcohol.

A 46-year-old chronic alcoholic patient with typical and severe congestive cardiomyopathy was studied hemodynamically on two separate occasions. The second study followed after a 1 1/2-year period of virtually complete abstention from alcohol and revealed that the left ventricular dysfunction had disappeared. Depsite persisting atrial fibrillation, the response to moderate exercise and to plasma volume expansion was within the normal range. When last seen, 29 months after initial hospitalization, the patient was symptom-free and was not given any treatment.


Comparison of five different stress testing methods in the ECG diagnosis of coronary artery disease. Correlation with coronary arteriography.

Five different stress testing methods: bicycle ergometer exercise (BE), treadmill exercise (TD), isoproterenol infusion test (IPN), dopamine infusion test (DPM), and atrial pacing (AP), were performed on 90 male patients who underwent coronary arteriography. Ischemic S-T segment depression of 1.0 mm or greater was used as the criterion for a positive test. Within the group of 56 subjects having significant coronary artery disease (CAD) the diagnostic sensitivity of the single tests was as follows: 64.3% for BE, 66.1% for TD, 69.6% for IPN, 41.1% for DPM, 75.0% for AP. For the 34 subjects with no CAD the folowing specificity was found: 88.2% for BE and for TD, 82.3% for IPN, 85.3% for DPM, 63.8% for AP. When the results of the different tests were combined, it was seen that the association of an ergometric test with IPN enhanced the sensitivity of the exercise test (p less than 0.05) without significantly decreasing the specificity.


Afterload as a predeterminant of haemodynamics and segmental wall motion following coronary artery occlusion.

Maximal changes in haemodynamics and segmental wall motion were seen 2 min after coronary occlusion and were examined in relation to the loading conditions of the left ventricle before occlusion in 20 open chest dogs. There was a significant inverse relationship between the preligation mean aortic pressure and the percentage decrease in stroke volume following ligation. This relationship was observed whether afterload was distributed randomly (mean aortic pressure ranging from 9.7 to 17.6 kPa [73 to 132 mmHg]) between all dogs (r = 0.65; P less than 0.001) or altered by methoxamine (+4 kPa [+30 mmHg]) and nitroprusside (-3.2 kPa [-24 mmHg]) within the same dog (r = 0.82; P less than 0.001; n = 8). Although occlusion of the anterior descending artery caused a small (+5.5%) but significant increase in end-diastolic length of the non-ischaemic epicardial segment, the capacity for compensatory ventricular dilatation was not dependent on preligation afterload. However, the capacity of the ischaemic segment to undergo systolic expansion was significantly greater (+30.2% of end-systolic segment length) in those dogs with the lowest preligation MAP (8 to 12 kPa [60 to 90 mmHg]) compared with systolic lengthening of only 15.8% in the high afterload group (15 to 18 kPa [112 to 135 mmHg]). These data indicate that the loading conditions of the left ventricle predetermine the extent of global and segmental left ventricular dysfunction during the early phase of acute ischaemic injury.


Left ventricular dysfunction of isolated working rat hearts after chronic alcohol consumption.

The mechanical, haemodynamic, and energetic functions of isolated perfused working hearts from chronic alcoholic and control rats were studied. Male Long-Evans rats were fed a nutritionally-complete liquid diet containing 38% of daily calories as ethanol (isocaloric replacement with dextrin-maltose for controls) for 34 to 48 weeks. Alcoholics and controls received either 7.4% (low-fat) or 21.0% (high-fat) of calories from lipid. Animals were matched by dry heart weight for comparisons and hearts were evaluated at a constant heart rate in an improved isolated ejecting heart perfusion preparation. Ventricular function curves and the response to 10(-7) mol . litre-1 dobutamine HCl were obtained during normoxic and hypoxic perfusion. In normoxia, the hearts from the high- and low-fat alcoholic animals exhibited a significantly lower response of left ventricular maximum systolic pressure, left ventricular maximum rate of pressure rise and maximum ejection velocity to dobutamine than did the controls. In hypoxia, the left ventricular maximum systolic pressure of the low-fat alcoholic hearts was slightly, but significantly, lower than that of the low-fat control hearts at the three filling pressures studied. Also in hypoxia, the increase in left ventricular maximum rate of pressure rise with dobutamine was significantly less in the alcoholic hearts than in controls. These data suggest that long-term consumption of moderate amounts of alcohol even along with a nutritionally-adequate diet can result in depressed myocardial contractility and pump function that may be manifest when the heart is subjected to stress conditions.


Factors determining delayed peak flow in canine myocardial reactive hyperaemia.

It has been suggested that delayed restoration of flow to the deeper layers of the myocardium is responsible for the gradual rise to peak flow rate characteristic of myocardial hyperaemia (RH). The distribution of coronary flow during RH was studied by injecting radiomicrospheres into the left atrium open chest dog preparations just prior to the end of a 15 s occlusion of the left circumflex branch. The artery was then reoccluded after 1, 2, or 4 s of RH. Myocardium perfused by the left anterior decending branch served as a control; the ratio of endocardial to epicardial (end/epi) perfusion in this bed averaged 1.14. During coronary occlusion and during the first second of RH the end/epi ratio in the hyperaemic zone averaged 50% of control, but rose progressively to equal control at the time of peak flow. Although evanescent subendocardial ischaemia may contribute to the gradual rise to peak flow rate it cannot by itself account for the time course of this response.


Comparison of the arrhythmogenic effect of myocardial infarction in the cat and dog.

Myocardial infarction was produced in dogs and cats by occlusion of the left anterior descending coronary artery. Arrhythmia was present in dogs but not in cats 6 to 48 h after occlusion. The absence of arrhythmia in cats was not due to persistent myocardial depressant effects of anaesthesia administered during surgery. Studies in cats with surgically-induced heart block revealed multiple ventricular pacemakers but no change in average ventricular rate following coronary occlusion. These results suggest that sinus overdrive, although not elevated compared with the dog, is sufficient to suppress arrhythmia in the cat. Further, since small dogs developed significantly less arrhythmia than large dogs, heart size may be an additional factor in explaining the absence of arrhythmia in the cat.


Augmentation of collateral blood flow to the ischaemic myocardium by oxygen inhalation following experimental coronary artery occlusion.

Since the mechanism by which oxygen reduces infarct size is not yet completely understood, we tested the hypothesis that breathing 100% oxygen may alter regional myocardial blood flow. In 23 anaesthetised open-chest dogs with acute occlusions of the left anterior descending coronary artery or of its apical branch, regional myocardial blood flow was determined by the microsphere technique at 15 and 30 min following coronary artery occlusion. Fifteen treated dogs were ventilated with 100% oxygen beginning 17 min after occlusion (ie, after the first determination of regional myocardial blood flow) and continuing until the end of the experiment, while the other 8 dogs served as controls and were ventilated continuously with room air. In treated dogs, following the administration of 100% oxygen, transmural flow at sites remote from the distribution of the occluded vessel (nonischaemic sites) decreased from 121 +/- 5 before oxygen to 108 +/- 6 cm3 . min-1 . 100g-1 (P less than 0.05). However, in the ischaemic sites it increased from 28 +/- 3 before oxygen to 32 +/- 3 cm3 . min-1 . 100g-1 (P less than 0.05). In the control dogs transmural flow, 15 and 30 min after occlusion, was, in nonischaemic sites, 118 +/- 7 and 125 +/- 10 cm3 . min-1 . 100g-1 NS, and in the ischaemic sites 27 +/- 4 and 25 +/- 3 cm3 . min-1 . 100g-1 NS, respectively. Thus, ventilation with 100% oxygen can augment perfusion of the ischaemic myocardium and this may be, in part, the mechanism by which it reduces infarct size.


Fibroblast function and the maintenance of the aortic-valve matrix.

The long-term behaviour of the aortic-valve allograft seems to be dependent on the maintenance of its matrix. Protein and collagen synthesis was studied in rat aortic-valves. Quantitative and qualitative methods proved the production of at least two protein pools. One protein pool is localised intracellularily with a 'turn-over' time of about 2 weeks, and a second pool is localised extracellularly with a 'turn-over' time of at least 8 weeks. The latter protein pool mainly consists of collagen.


Effects of heparin and protamine on left ventricular performance in the dog.

The effects of protamine on left ventricular (LV) function were measured under conditions of controlled heart rate and proximal aortic pressure in eight anaesthetized, heparinised dogs. Protamine 3 mg.kg-1 produced a 21% decrease in LV dP/dt max, a 43% decrease in cardiac output, a 47% decrease in stroke work and decreases in systolic and diastolic pressures (-16%, -19% respectively). Protamine 6 mg.kg-1 resulted in a 17% decrease in LV dP/dt max, a 26% decrease in cardiac output, a 50% decrease in LV stroke work and 25 and 30% decreases in systolic and diastolic pressures. These results show that an impairment of LV function plays an important part in the circulatory depression produced by protamine.


Myocardial subcellular fractionation studies on cardiomyopathic Syrian hamsters.

Myocardial homogenates from control animals and from hamsters with hereditary cardiomyopathy were subjected to analytical subcellular fractionation and enzymic microanalysis. Animals without ventricular hypertrophy or overt heart failure were used in this study. The principal subcellular organelles were characterised by density gradient centrifugation. Apart from evidence of enhanced lysosomal and peroxisomal fragility, probably secondary to the intracellular oedema, the intracellular organelles investigated in this study were unaffected by the myopathic process. Highly significant increases in 5'-nucleotidase activity, a marker for the sarcolemma, and an increased equilibrium density of this organelle were found in the myopathic tissue. Ultrastructural studies revealed patchy myocytolysis associated with lysosomes and with more extensive invaginations of the sarcolemma. It is suggested that a primary defect in membrane composition, leading to increased cation permeability, is the underlying abnormality in the myopathic hamster.


Role of angiotensin II in the development of peripheral vasoconstriction during cardiopulmonary bypass.

The possible relationship between angiotensin II -- the end product of the renin-angiotensin system, and the increase in peripheral vasoconstriction associated with cardiopulmonary bypass, has been investigated in 12 patients undergoing elective open-heart surgical procedures. Plasma angiotensin II (AII) levels were measured by radio-immunoassay at the start and the end of the period of cardiopulmonary bypass. Measurements of peripheral vascular resistance index were made at the times of AII sampling. Plasma AII levels rose during CPB from 78.0 to 231.3 pg.cm-3 (normal values less than 35 pg.cm-3). Peripheral vascular resistance index also rose during perfusion from 20.87 to 27.83 units. The rise in plasma AII levels and in peripheral vascular resistance index were correlated for each of the 12 patients. A highly significant correlation was obtained (r = 0.91; P less than 0.001). These results confirm the presence of parallel rises in plasma angiotensin II levels and in peripheral vasoconstriction during conventional non-pulsatile cardiopulmonary bypass, and suggest that increased plasma AII levels may be principal causative factor in the increased vasoconstriction associated with open-heart surgical procedures.


Fallibility of the epicardial electrocardiogram in quantitation of myocardial necrosis.

Estimation of infarct size utilising the epicardial electrocardiogram has been the subject of considerable controversy. The present study re-examines this technique in a dog model. It demonstrates that epicardial Q waves and S-T elevation are qualitative markers of local necrosis with different degrees of reliability; neither, however, is quantitatively related in a simple linear fashion to extent of necrosis. Conclusions from previous studies have been influenced both by different mathematical analyses of data and the inclusions of nonhomogenous sites in linear regression models.


Electrophysiological actions of mexiletine on isolated rabbit atria and canine ventricular muscle and purkinje fibres.

The electrophysiological effects of varying concentrations of mexiletine on isolated rabbit sinus node and atrial preparations. Purkinje fibres, Purkinje-fibre-ventricular muscle junction and distal conduction system ('gate') were studied in oxygenated Tyrode solution at 35 degrees C using standard microelectrode techniques. 'Therapeutic' concentrations of mexiletine (0.5 to 2.0 micrograms.cm-3) had little effect on the atrial action potentials or on sinus node automaticity but sino-atrial conduction was delayed. In Purkinje fibres, these concentrations of the drug depressed the dV/dtmax of phase 0, conduction velocity and membrane responsiveness accompanied by significant shortening of the action potential duration and the effective refractory period, the change in the former always being greater than that in the latter. Mexiletine decreased antegrade as well as retrograde conduction at the Purkinje-fibre-ventricular muscle junction, while producing a uniform shortening of the action potential duration in the distal conduction system without a preferential effect at the 'gate'. The mechanisms of antiarrhythmic actions of mexiletine are thus complex but resemble those of lignocaine in superfused isolated cardiac muscle.


Extracellular potassium activity changes in the canine myocardium after acute coronary occlusion and the influence of beta-blockade.

Extracellular potassium activity before and after coronary occlusion was measured in the canine heart by means of potassium-selective surface electrodes. In the ischaemic myocardium potassium activity rapidly increased from a preocclusion value of 3.2 +/- 0.3 mmol.litre-1 to 10 +/- 0.6 mmol.litre-1 within the first 5 min and to about 11.3 +/- 0.5 mmol.litre-1 after 10 min of ischaemia (range from 9.5 to 14.5 mmol.litre-1). Following the initial 10 min of ischaemia no further increase was measured. In the non-ischaemic area potassium activity remained constant. Acute beta-blockade significantly attenuated the initial rate of increase in potassium activity; however, beta-blockade did not influence maximal values of extracellular potassium activity measured after occlusion. Lowering of heart rate by vagal stimulation did not modify the pattern of increase in potassium during acute ischaemia. Following ventricular fibrillation, a slow but continuous rise in potassium activity was found. These results demonstrate that extracellular potassium activity in the acutely ischaemic myocardium is considerably higher than indicated by the technique of coronary vein sampling and is in the range necessary for the development of re-entrant arrhythmias in the early phase after coronary occlusion.


Effect of mexiletine on monophasic action potentials recorded from the right ventricle in man.

The effect of mexiletine, a new antiarrhythmic agent, on ventricular refractoriness and monophasic action potentials recorded from the right ventricle was studied in nine subjects. The effective refractory period of the right ventricle was determined by the extra stimulus technique using a pacing electrode situated at the right ventricular apex. Following this determination the right ventricular apex was paced at a constant cycle length and premature stimuli were introduced starting at a coupling interval of 2 ms greater than the ventricular refractory period and then at progressively increasing coupling intervals of 5 ms increments. Simultaneous recordings of monophasic action potentials of both the regular paced beats and the induced premature beats were made using a  specially designed suction electrode catheter. The monophasic action potential durations were measured at 50% and 90% repolarisation. All these control measurements were repeated after an intravenous dose of 2 mg.kg-1 body wt. of mexiletine. The results showed that mexiletine did not significantly change the effective ventricular refractory period nor did it alter the monophasic action potential duration of the regular paced beat. The drug did, however, significantly prolong the monophasic action potential duration of the early induced premature beats and it is possible that this property of the drug may be related to its antiarrhythmic activity.


Effect of mexiletine on conduction of premature ventricular beats in man: a study using monophasic action potential recordings from the right ventricle.

Ventricular conduction intervals between a stimulating pacemaker electrode at the right ventricular apex and an impulse detecting monophasic action potential electrode at the right ventricular septum were measured in nine subjects. The right ventricle was paced at a constant rate and programmed premature ventricular stimuli were introduced after every eighth paced beat beginning at the refractory period. The ventricular conduction intervals were measured from the pacemaker artefact to the onset of depolarisation of the MAP recording. In the control recordings a short period of prolonged (subnormal) conduction lasting for 5 to 26 ms after the refractory period was present in six of the nine subjects. In eight subjects a period of 'supernormal' conduction lasting from 50 to 180 ms was present. The effect of mexiletine was to increase the subnormal conduction and to abolish the supernormal conduction. It is concluded that a small degree of supernormal conduction occurs in the normal human ventricle possibly as a result of phase 4 depolarisation of cells of the specialised conducting system.


Coupling interval, exit block, and periodicity of ventricular parasystolic rhythm.

The electrocardiograms in this study of parasystolic rhythm were tape recorded and then analysed with a special purpose hybrid computer. The rate of appearance of specific inter-ectopic intervals was shown to change significantly with small changes in either the sinus or parasystolic pacemaker period. Natural changes in the period of the ectopic pacemakers were observed over several hours. Changes amounting to 14% within 10 min and 18% overall were observed in one patient, and a gradual lengthening of 10% over 3 h in another. A previously undescribed form of exit block has been discovered in one patient where the block remained active for a given time only after propagation from the parasystolic focus. Different interectopic intervals were shown to contribute to specific and restricted coupling interval locations in diastole. Hence this form of exit block, by preventing some inter-ectopic intervals from propagating, limited the locations in diastole in which parasystolic ectopic complexes could appear. In this case later diastolic complexes were inhibited and hence fusion complexes were completely absent. Parasystolic rhythm, with and without the exit block described, was simulated successfully by a digital computer. The simulations aided our understanding of the clinical data.


Release of alpha hydroxybutyrate from neonatal rat heart cell cultures exposed to anoxia and reoxygenation: comparison with impairment of structure and function of damaged cardiac cells.

Spontaneously beating monolayer cultures of neonatal rat heart cells first exposed to depletion of oxygen and metabolic substrates for 1 to 7 h (anoxia). Subsequently the cultures were resupplied with oxygen and substrates (reoxygenation). The release of alpha-hydroxybutyrate dehydrogenase (HBDH) from the cells, the extent of necrosis, and the changes in spontaneous contractile activity were measured. HBDH release was observed to start after 1 h of anoxia and to increase to 84% of intracellular HBDH activity after 7 h of anoxia. Reoxygenation of anoxic heart cells is associated with accelerated HBDH release (oxygen paradox). The activity of HBDH released by cardiac cells, the number of necrotic cells and the impairment of beating capacity of the cells depend on the duration of the anoxic period in a similar way. This study demonstrates that cardiac cell death can be assessed quantitatively and reliably by the measurement of the activity of HBDH released by the cells.


Electrophysiological effects of ethmozin on canine myocardium.

The electrophysiological effects of ethmozin on canine myocardium were studied in anesthetised open-chest animals and in superfused Purkinje fibres. The drug did not change spontaneous sinus node cycle length and atrioventricular conduction time when selectively injected into the sinus nodal artery and into the posterior septal artery, respectively. Right and left ventricular diastolic excitability threshold and refractory period were increased following the intravenous administration of ethmozin, 4 mg/kg-1. Ethmozin (3 to 5 mg/kg-1 i.v.) markedly increased conduction delay in the ischaemic zone of the left ventricle during acute coronary artery occlusion. This change was associated with the development of ventricular fibrillation in 50% of the dogs. In vitro, ethmozin 1 X 10(-3) and 1 X 10(-2) g.litre-1 shortened Purkinje fibres' action potential duration. At 1 X 10(-2) g.litre-1, ethmozin decreased the rate of rise of phase 0, and slightly reduced action potential amplitude.


Changes in growth kinetics of jejunal epithelium in mice maintained on an elemental diet.

Changes in the kinetics of the intestinal epithelium were observed in mice maintained on an elemental diet containing hydrolysed protein and medium chain triglycerides. An increase in the length of the villi seen shortly after commencement of the diet was followed by a reduction in the rate of proliferation in the crypt. After 7 days on the diet, an equilibrium state was reached with the cellularity of the villi being 120% that of control while the number of proliferative cells/crypt was reduced by 35%. The proliferative response of the crypt following irradiation occurred 16 hr later in diet-fed mice than in controls. It was postulated that, because of the increased cellularity of the villus compartment in diet-fed mice, additional time was required to reduce the number of villus cells to a critical level at which a proliferative response is induced in the crypt.


Estimation of effective eosinopoiesis and bone marrow eosinophil reserve capacity in normal man.

The eosinophil reserve capacity of the post-mitotic granulocyte compartment in the bone marrow and the effective eosinopoiesis in three haematologically normal men have been quantified by means of kinetic parameters of [3H]thymidine flash-labelled peripheral blood eosinophils. From (a) the time of the appearance in the blood of labelled eosinophils after the tracer injection, (b) the inflow characteristics of the labelled eosinophils in the blood and (c) the magnitude of the eosinophil granulocyte pool in the venous blood, the effective eosinopoiesis (i.e. the eosinophil turnover) was calculated to range between 0.014 and 0.031 x 10(9) cells/kg body weight per day (mean 0.22 x 10(9) cell/kg per day). The post-mitotic eosinophil reserve capacity of the bone marrow ranged from 0.09 to 0.20 x 10(9) cells/kg body weight (mean 0.14 x 10(9) cells/kg). The large reserve pool and the high turnover rate may contribute to sudden rises of the peripheral blood oesinophil counts in some cases of eosinophilia.


Further studies on mobilization of CFUs.

Mobilization of CFUs from haemopoietic tissues into circulation was studied after injection of different bacterial lipopolysaccharides (LPS), zymosan, phytohaemagglutinin (PHA), concanavalin A (Con A), trypsin and di-isopropyl-fluorophosphate-inhibited trypsin. All bacterial LPS used gave an increase of CFUs in the peripheral blood at 1 h after i.v. injection. Some variation in activity could not be excluded. As with Salmonella typhosa LPS, zymosan gave an increase in circulating CFUs during the first few hr and a second peak a few days later. After injection of zymosan as well as S. typhosa LPS the second peak in the blood was accompanied by a large increase in CFUs numbers in the spleen. PHA gave an immediate mobilization of CFUs, but the mobilization after injection of Con A during the first few hr occurred more slowly. After injection of S. typhosa LPS, zymosan and PHA the blood C3 level was found to be depressed considerably. This might indicate that the complement system is involved in the early mobilization of CFUs. Dexamethasone, a synthetic hormone which has been reported to give sequestration of several cell types in the bone marrow, did not inhibit the early and late mobilization of CFUs which normally occurs after injection of S. typhosa LPS.


The effect of temperature on the turnover of taste bud cells in catfish.

Renewal of taste bud cells on the barbels of channel catfish was studied. Groups of catfish, held in and acclimitized to 14 degrees C, 18 degrees C, 22 degrees C and 30 degrees C dechlorinated tap water were injected with [3H]thymidine (3.0 muCi/g body weight intraperitoneally). Barbels were sampled at various times after injection and prepared for light microscope autoradiography. Results show that epithelial cells surrounding the taste buds divide and some of their daughter cells migrate into the taste buds. The time at which 50% of the labelled cells have degenerated is taken as the average turnover time or average life span of the taste bud cells. The average life span as well as the time spent inside the taste buds is highly temperature-dependent. At 14 degrees C, 18 degrees C, 22 degrees C and 30 degrees C the average life span is on the order of 40, 30, 15 and 12 days respectively. Further studies indicate that both light and dark staining cells of the taste bud were labelled.


A cell kinetic model to explain the time of appearance of skin reaction after X-rays or ultraviolet light irradiation.

Skin reactions to various doses of X-rays (300 and 10 kV) and ultraviolet light (u.v.) have been compared using hairless mice. Two regions of epidermis with widely differing cell kinetics and gross structure have been compared. Little evidence could be found to support the idea that the early phases of the reaction are dependent on cell cycle time. The data can be explained by a model based on the assumption that epidermis contains only a small fraction of clonogenic (stem) cells and this fraction may vary in different epidermal regions. X-rays appear to exert their greatest destructive action on these clonogenic cells while u.v. is more indiscriminate in its action, killing both clonogenic and non-clonogenic cells.


The enhancement of haemopoietic stem cell recovery in irradiated mice by prior treatment with cyclophosphamide.

Studies are reported of the enhancement of stem cell recovery following whole body irradiation as a result of prior administration of cyclophosphamide. It is shown that the much larger enhancement of regeneration observed for the hosts own surviving stem cells, compared to the regeneration of injected bone marrow stem cells, is due to the different numbers of stem cells initiating the regeneration in conjunction with the time course of stem cell regeneration. The results show that the environmental changes produced by cyclophosphmide greatly enhance haemopoietic recovery even though at the dose used this agent is relatively toxic to stem cells. Furthermore it has been shown that the level of stem cell regeneration is nearly independent of the gamma-ray dose in the range 3-8 gray (300-800 rad). If human bone marrow should respond similarly it follows that regeneration produced by cytotoxic drugs administered prior to radiation embodies a considerable safety factor as far as recovery of the haemopoietic system is concerned.


Circadian rhythms in mouse epidermal basal cell proliferation. Variations in compartment size, flux and phase duration.

Several kinetic parameters of basal cell proliferation in hairless mouse epidermis were studied, and all parameters clearly showed circadian fluctuations during two successive 24 hr periods. Mitotic indices and the mitotic rate were studied in histological sections; the proportions of cells with S and G2 phase DNA content were measured by flow cytometry of isolated basal cells, and the [3H]TdR labelling indices and grain densities were determined by autoradiography in smears from basal cell suspensions. The influx and efflux of cells from each cell cycle phase were calculated from sinusoidal curves adapted to the cell kinetic findings and the phase durations were determined. A peak of cells in S phase was observed around midnight, and a cohort of partially synchronized cells passed from the S phase to the G2 phase and traversed the G2 phase and mitosis in the early morning. The fluctuations in the influx of cells into the S phase were small compared with the variations in efflux from the S phase and the flux through the subsequent cell cycle phases. The resulting delay in cell cycle traverse through S phase before midnight could well account for the accumulation of cells in S phase and, therefore, also the subsequent partial synchrony of cell cycle traverse through the G2 phase and mitosis. Circadian variations in the duration of the S phase, the G2 phase and mitosis were clearly demonstrated.


Studies on the mechanism of haemopoietic stem cell (CFUs) mobilization. A role of the complement system.

A variety of substances can mobilize haemopoietic stem cells (CFUs) into the peripheral blood. In this study the involvement of the complement system in the mobilization process was investigated. Pretreatment of mice with the complement-activating factor of cobra venom (CoF), which lowered the serum C3 levels to 10-25% of the normal value, could completely prevent CFUs mobilization induced by high doses of CoF, endotoxin (ET) from Salmonella typhosa, inulin, zymosan and the proteolytic enzymes proteinase and trypsin. On the other hand, mobilization induced by the polyanions dextran sulphate and the copolymer of polymethacrylic acid and styrene could not be prevented, or at least affected only slightly. There appears to be a relationship between the extent of decomplementation by CoF and the extent of CFUs mobilization induced by ET. The results indicate that certain agents mobilize CFUs via the complement system, whereas other agents induce CFUs mobilization independent of the availability of complement components.


Non-random association of mitotic cells from cultured human lymphocyte suspensions.

By using chromosome markers in two separate cell lines of a human dispermic chimera, it was shown that 4.9% of metaphases in suspensions of PHA-cultured lymphocytes were paired because of non-random factors. A similar amount of metaphase pairing occurred in cultured lymphocytes of normal donors, and evidence from the relative mitotic cycles of the paired cells indicated that some of this pairing was non-random. Such non-random pairing could be a source of bias in cell kinetic and other studies involving metaphase cells in lymphocyte cultures.


Transit times through the cycle phases of jejunal crypt cells of the mouse. Analysis in terms of the mean values and the variances.

Mean transit times as well as variances of the transit times through the individual phases of the cell cycle have been determined for the crypt epithelial cells of the jejunum of the mouse. To achieve this the fraction of labelled mitoses (FLM) technique has been modified by double labelling with [3H] and [14C]thymidine. Mice were given a first injection of [3H]thymidine, and 2 hr later a second injection of [14C]thymidine. This produces a narrow subpopulation of purely 3H-labelled cells at the beginning of G2-phase and a corresponding subpopulation of purely 14C-labelled cells at the beginning of the S-phase. When these two subpopulations progress through the cell cycle, one obtains FLM waves of purely 3H- and purely 14C-labelled mitoses. These waves have considerably better resolution than the conventional FLM-curves. From the temporal positions of the observed maxima the mean transit times of the cells through the individual phases of the cycle can be determined. Moreover one obtains from the width of the individual waves the variances of the transit times through the individual phases. It has been found, that the variances of the transit times through successive phases are additive. This indicates that the transit times of cells through successive phases are independently distributed. This statistical independence is an implicit assumption in most of the models applied to the analysis of FLM curves, however there had previously been no experimental support of this assumption. A further result is, that the variance of the transit time through any phase of the cycle is proportional to the mean transit time. This implies that the progress of the crypt epithelial cells is subject to an equal degree of randomness in the various phases of the cycle.


Interference of sex-related factors in the response of liver cells to experimental mitotic stimuli.

Stimulation of liver cell multiplication was obtained under two different experimental conditions. (1) A single injection of casein solution resulted in (a) an identical synchronized mitotic wave response in 10-day old male and female rats and (b) a significantly lower response in adult male rats compared to females, a difference which was reduced by castration of males at birth but essentially maintained if animals were operated when 10 days old. (2) Partial hepatectomy shortly after puberty resulted in active hepatocyte multiplication occurring 3 hr earlier in females were ovariectomized at birth and significantly reduced when they were spayed at a later age. Hepatocytes of castrated females entered actively into S phase 2 hr later than the sham-operated controls. Unilateral ovariectomy on the other hand indicated that during compensatory and/or hypercompensatory activity of the single ovary there was a maximum difference between the male and female rate of [3H]thymidine uptake in liver nuclei 20 hr after hepatectomy. A further kinetic study (t = 25, 30,40, 65, 90 hr) indicated no significant sex-related difference in the number of S phases per 10,000 cells. The DNA content of regenerating versus control livers was comparable in both sexes at t = 22 and 90 hr but higher in females at t = 40 and 65 hr. A possible early postnatal interference of certain hormonal mechanisms in the receptivity to mitotic stimuli is postulated and discussed.


Effects of intestinally absorbed thymidine on tritiated thymidine utilization.

Experimental evidence presented suggests that [3H]TdR can be rapidly and efficiently transported from the intestine to the systemic circulation. This pathway for thymidine transport may be physiologically important since administration of cold thymidine in the drinking water enhances the utilization of a parenterally injected dose of [3H]TdR in several body tissues of the mouse.


Alteration of neonatal rat parotid gland acinar cell proliferation by guandethidine-induced sympathectomy.

Newborn rats were injected with guanethidine-sulfate (20 micrograms/g body weight) every 48 hr from 12 hr after birth until day 14 (eight injections per animal). The guanethidine treatment resulted in an 86% absolute reduction in cell number in the superior cervical ganglia of 15 day old rats. The cells which remained after guanethidine treatment showed destruction of mitochondria and an extensive decrease in endoplasmic reticulum. Chemical sympathectomy with guanethidine induced a 3.1 hr lengthening of the acinar cell generation cycle time (17.4 hr to 20.5 hr), resulting from a longer G1 period (6.9 hr in the control group as compared to 10.5 hr in the guanethidine-treated group), as well as a cecrease in the mean percentage of [3H]thymidine-labeled acinar cells (22.3 +/- 0.5% to 19.3 +/- 0.5%) and mean acinar cell mitotic index (2.6 +/- 0.2% to 2.1 +/- 0.1%). A circadian rhythm was found to exist in parotid gland acinar cell mitotic activity of 15 day old rats and the amplitude of the rhythm was reduced from 26.5% to 14.9% in guanethidine-treated rats. This study indicates that the diminution of sympathetic influence on the developing parotid gland results in a slight, but significant alteration in acnar cell proliferation.


Low level incorporation of tritiated thymidine into the nuclear DNA of Purkinje neurons of adult mice.

Adult mice were pulse labeled with tritiated thymidine [3H]TdR and killed 9 hr later. A low level incorporation of [3H]TdT into the nuclear DNA of Purkinje neurons was found in autoradiographs. Enzymatic digestions with DNase and with RNase in combination with autoradiographic grain counts indicate that a portion of nuclear DNA is not stable in the Purkinje nucleus. These results are discussed in light of reports of the stable nature of DNA in Purkinje neurons of adult mice.


Ultrastructure of the swim bladder of the goldfish, Carassius auratus.

The swim bladder of the cyprinid Carassius auratus (goldfish) is a two-chambered organ connected to the esophagus by a pneumatic duct. The anterior chamber is lined by a single type of squamous epithelial cell. Two types of epithelial cells are present in the posterior chamber. Flattened cells with differences in the electron density of the cytoplasm line most of the chamber. Darker cells generally contain large amounts of glycogen. Cuboidal epithelial cells also occur in the posterior chamber. A glandular layer external to the muscularis in the posterior chamber is composed of large cells containing little glycogen, an extensive Golgi apparatus, and numerous mitochondria with single large granules. Capillaries and nerves are present in large numbers in this layer. Blood vessels form micro-retia mirabilia in the submuscular layer external to the glandular layer. Vessels are of two distinct types with wide lumina and flattened endothelium characterizing the venous vessels. Arterial vessels and have smaller lumina, thick endothelial cells with prominent pinocytotic vesicles, and surrounding pericytes. Collagen is present in three forms in this swim bladder - large tactoids in the tunica externa of the anterior chamber, smaller tactoids in the lamina propria of the posterior chamber, and small fibrils in all other areas.


The androgenic effect on the fine structure on the Harderian gland in the male hamster.

A sexual dimorphism of the hamster Harderian gland at the ultrastructural level has been reported. The effect of testosterone on the fine structure of the gland from castrated male golden hamsters is reported here. Harderian glands from the following three groups of animals were examined at regular intervals up to 60 days after castration: (1) castrated; (2) castrated-sham-injected, receiving 0.1 ml sesame oil per day; (3) castrated-testosterone-injected, receiving 2 mg testosterone propionate in 0.1 ml sesame oil per day. In groups 1 and 2, clusters of cylindrical tubules, typical of the male gland, decreased in number and disappeared almost completely 2 wailed in these two groups throughout the remaining period of experiment. On the other hand, these changes were prevented in the group of castrated animals maintained on testosterone propionate. It is concluded that castration modified the ultrastructure of the male hamster Harderian gland toward the female type and that daily administration of testosterone propionate prevented this change.


Fenestration of the epithelium lining the roof of the fourth cerebral ventricle in amphibia.

Scanning electron microscopy of the caudal end of the roof of the fourth cerebral ventricle in four amphibian species shows that numerous pores occur between the ependymal cells. These pores have diameters ranging from 5--100 micron; they permit bluk flow of cerebrospinal fluid out of the ventricular system into the subarachnoid space.


Development of cell-to-cell relationships in the thyroid gland of the chick embryo.

Thyroid glands of 7 to 21 day-old chick embryos were examined by electron microscopy using freeze-fracture and thin-section preparations. The primitive follicle lumen first appears between two adjacent epithelial cells in 8 day-old embryos, and is formed in the region of a focal tight junction (macula occludens). The focal tight junction develops into the zonula occludens when the primitive follicle lumen first forms. The zonula occludens is, at first, composed of 4.6 +/- 2.45 strands, but with increasing embryonic age the number of strands increases to 5.9 +/- 1.41 in 13 day-old, and 8.0 +/- 1.75 in 19 day-old embryos. Thyroglobulin stored within the embryonic gland lumina is isolated from the mesenchymal tissue even at the first appearance of these follicle cavities. Well developed gap junctions already occur in the thyroid gland of the 7 day-old embryo, so that an intimate relationship and communication between these cells already exists at the time of their functional differentiation.


A histochemical study of the innervation of the cerebral blood vessels in the domestic fowl.

Adrenergic and cholinergic nerves innervating the cerebral arteries of the domestic fowl were examined by specific histochemical techniques. The adrenergic nerve plexuses of the cerebral carotid system are markedly denser than those of other vertebrates observed by similar techniques. They form longitudinally elongated meshworks of fine fibres in the vascular wall of the arterial branches. Those innervating the vertebro-basilar system are less dense and more elongated, and, as the size of the artery diminishes, the fibres of the plexus become coarser. In the small pial and parenchymal arteries they are reduced to a few fibres running parallel to, or spiralling around the vascular axis. The cholinergic nerve plexuses are not as dense as the adrenergic system. The acetylcholinesterase activity is very weak, except in the plexuses innervating the cerebral carotid artery and proximal portion of the anterior and posterior rami. In the vertebro-basilar system, a few thick nerve bundles run alongside the blood vessels of the vertebral and basilar arteries. Cholinergic nerves enter the cranial cavity along the internal carotid, the vertebral and possibly the cerebroethmoidal arteries. Intracerebral capillaries and some arterioles are not innervated with cholinergic and adrenergic fibres of peripheral origin, but with ones arising from parenchymal nerve cells.


Impermeability of hagfish cerebral capillaries to horseradish peroxidase. An ultrastructural study.

Brain capillaires and their permeability to intravenously injected horseradish peroxidase, HRP, (MW: 40,000) were examined electron-microscopically in an attempt to find a structural explanation for the poorly developed blood-brain barrier in the hagfish, Myxine glutinosa. In particular, it was the aim of this study to examine the role of the numerous endothelial vesicles and tubules in the transport of this tracer between blood and brain. Many of the vesicles and tubules were found to be in continuity with the luminal or abluminal surfaces, but tubules generating channels through the endothelial cells were never observed. The cleft between adjacent endothelial cells was obliterated by punctate junctions. HRP, which was aloowed to circulate for up to 35 min, was not found in the basal lamina or in the surrounding brain parenchyma. Few of the luminal vesicles and tubules were marked by the tracer. In the intercellular cleft HRP was stopped by the junctions. It is concluded that the hagfish like other vertebrates has a blood-brain barrier to HRP, and the numerous vesicles and tubules occurring in hagfish brain endothelium are not involved in the transendothelial transport of this macromolecule.


Premetamorphic changes in the ultrastructure of Calliphora fat cells.

In the fat body of Calliphora a drastic reorganization of the cell structure, which is related to premetamorphic functional changes, can be observed during the 3rd larval stage of development. These changes include an accumulation of protein storage granules, a decrease in the relative volume of the mitochondria and the surface area of endoplasmic reticulum membrane, and the disappearance of vacuoles. "Absolute" values obtained for organelle areas and membrane perimeters confirm the assumption that large numbers of organelles are eliminated by autophagic activity prior to the pupation period. A temporary restoration of the endoplasmic reticulum is found immediately before pupariation. Large variations in organelle density were found between individual fat cells and between the nuclear, mid- and peripheral regions of the cytoplasm.


The pigmentary system of planaria. I. Morphology.

The pigmentary system of the planaria, Dugesia gonocephala s.l. (Platyhelminthes, Turbellaria, Tricladida), has been studied by light and electron microscopy. The system consists of granules contained in chromatophore-like cells embedded in the parenchyma. The cell processes penetrate between the muscle layers and extend to the sub-epidermal basal lamina. The nature of the pigment and the comparative anatomical significance of the chromatophore structure is discussed.


Experimental studies of apocrine secretion in the dorsal prostate epithelium of the rat.

Rat dorsal prostate epithelium was studied in intact adult animals, in animals castrated for three days and in rats after inhibition of prolactin secretion. Thin sections, electron-microscopic autoradiographs and freeze-fracture replicas were used to analyze the process of apocrine secretion in this gland. The rough endoplasmic reticulum and the Golgi apparatus of the secretory cells are well developed, but secretory granules are absent. The only sign indicating release of secretory material is the appearance of blebs originating from the apical plasma membrane. Freeze-fracture replicas of the apical plasma membrane reveal that the blebs develop randomly from the bases of microvilli-like protrusions. In vitro pulse labeling of the proteins using 3H-leucine resulted in a labeling of the apical blebs. A post-castration period of three days was sufficient to reduce drastically the number and size of the apical blebs conhree weeks by application of lisuride, a synthetic ergot alkaloid, also induced regressive changes in the secretory cells. The apical blebs were still present, but they were shrunken and their content appeared condensed. These experimental conditions proved that the apical blebs are closely related to the functional activity of the cells and are interpreted as true apocrine secretion in the rat dorsal epithelium.


Autoradiographic detection of indolamine and catecholamine neurons in the nervous system of Owenia fusiformis (Polychaeta, Annelida).

Light- and electron-microscopic autoradiographic studies were carried out on Owenia to detect selectively catecholaminergic and indolaminergic neurons at two appropriate body levels according to the regenerative properties of this annelid, i.e. in the 1st and the 4th abdominal segments. Autoradiographically, intense 3H-5-hydroxytryptamine accumulation is seen in the 1st abdominal segment, and a less intense autoradiographic reaction in the 4th segment. Roughly, a similar difference in the distribution of the label is seen at both levels following 3H-noradrenaline administration. These observations, confirmed by a quantitative uptake analysis, suggest the presence of catecholaminergic and indolaminergic neurons in Owenia.


Probit analysis of the atrioventricular (AV) junctional tissues of the ferret heart.

Probit frequency analysis, a graphic method for determining whether a population is normally distributed, skewed, or multinodal, was used to determine whether P cells are present in different regions of the AV junction in the ferret heart. This analysis indicated that at least 95% of the cells of the transitional zone, superficial AV node, deep AV node, and distal AV bundle of the ferret heart are morphologically homogeneous. In the proximal AV bundle a large cell population is found in addition to the AV bundle cells. The probit analysis was also used to characterize the shape of the cells of each region of the AV junction further. AV nodal cells are not as elongated as the atrial muscle cells and AV bundle cells. These nodal cells also do not branch as extensively as the AV bundle cells.


The fine structure of the parietal retinas of Anolis carolinensis and Iguana iguana.

An electron microscopic examination of the parietal retinas of Anolis carolinensis and Iguana iguana demonstrated within each retina (1) two distinct populations of neurons, (2) two populations of glia, and (3) a population of photoreceptors which could not be subdivided. A small population of very electron-dense cells, in many respects similar to photoreceptors, was also found in the iguana. Correspondingly dark processes were found in the plexiform layer of each retina. Parietal photoreceptors generally resemble cones of the lateral eye. Glial cells were sub-classified on the basis of the location of their somata and the disposition of their processes. Neurons were identified by virtue of their cytology and their reception of axosomatic ribbon synapses from unidentified plexiform layer processes. Neuronal subtypes were located on opposite sides of the plexiform layer. Neurons distal to that layer were found to project the initial segments of their processes into the plexiform layer parallel to its long axis, while neurons central to the plexiform layer projected axons centrally and dendrites radially into the plexiform layer. The existence of at least two neuronal populations and of interphotoreceptor synapses suggests that photosensory processing within the parietal retina may be more complex than previously assumed.


Estrogen-induced ultrastructural changes in cultured chick embryo hepatocytes.

Administration of estradiol-17-beta induces the synthesis of vitellogenin in primary cultures of chick embryo liver. The ultrastructural changes accompanying steroid induced vitellogenin synthesis were investigated in hepatocytes cultures incubated for 0, 12 and 24 h following hormonal treatment. Both electron microscopy and immuno-chemical techniques were used. The immuno-fluorescence data indicate that the cultures contain a cell population of 90--95% hepatocytes, both in control and estradiol-treated groups. Ultrastructurally, cultured hepatocytes are similar to in vivo ones, except for a reduced accumulation of storage materials, glycogen and lipids. In the estradiol-treated cultures hepatocytes show an accumulation of free ribosomes, enlargement of rough endoplasmic reticulum, and development of the Golgi apparatus.


Reformation of gap and tight junctions in regenerating liver after cholestasis.

Morphometric analysis of the alterations in interhepatocyte junctions induced by bile duct ligation revealed that after 48 h, during which time the serum bilirubin increased 6 to 8 fold, the membrane area occupied by gap junctions on the apico-lateral and medio-lateral sides decreased from 3.6% in controls to 0.02% in the ligated group. The strands of the zonulae occludentes were reduced in number and showed increased discontinuities. Within 45 min of recanalization of the common bile duct, clusters of particles appeared within and adjacent to the tight junctional areas or in the lateral hepatocyte membrane. Subsequently, the particle aggregations localized in the apico-lateral membrane areas increased in number and size becoming finally indistinguishable from those of controls within 96 h after the onset of recanalization. The zonulae occludentes also rearranged and reestablished their original structure during this period. The serum bilirubin fell to normal within 24 h of recanalization. It is concluded that metabolic and ultrastructural restitution associated with the recanalization of the ligated bile duct have no strict temporal correlation to one another. These studies provide further evidence that alterations in gap and tight junctions induced by pathological processes, e.g. during bile duct ligation, are completely reversible when regeneration occurs.


Subsurface cisterns in paraventricular nuclei of the hypothalamus of the rat.

Structures identified as subsurface cisterns (SSC's) were found in neurons of the paraventricular nuclei of the rat hypothalamus. They appeared as cytoplasmic organelles consisting most often of stacks of parallel cisterns apposed to the neuronal plasmalemma. These SSC's were located in the interneurons of the parvocellular system, but not in neurosecretory cells and glial cells. SSC's were seen at zones of cytoplasm apposed to neuronal or glial cell processes, showing in some instances specific relationships with synaptic areas. The morphological features of these SSC's are described, and their possible functional significance is briefly discussed.


The fine structure of the hypostome and mouth of hydra. I. Scanning electron microscopy.

The hypostome and mouth of fresh-water Hydra were examined by scanning electron microscopy. The external surface of the hypostome possesses cnidocils, possibly sensory hairs, and small spiny protrusions surrounding the mouth; the internal surface has cylindrical microvilli, free flagella and adherent flagella. The adherent flagella are most numerous close to the mouth where they cause the cell surface to appear smooth when viewed at low magnifications. Free flagella and leaf-like microvilli increase in prominence towards the tentacles and enter on proper. The edge of the mouth has an abrupt boundary marking the apposition of epidermal and gastrodermal cells. A transitional groove occurs at the boundary and the cells underlying the groove are smaller than those on other regions of the hypostome. The transition groove may represent a site of cell loss in normal cell turnover. Some of the small underlying cells may represent nervous elements involved in regulating hypostome activity during the feeding reation.


The fine structure of the hypostome and mouth of hydra. II. Transmission electron microscopy.

The normal morphology of the hypostome and mouth of hydra were examined by transmission electron microscopy with conventional thin sections and freeze-fracture replicas. Myonemes of the hypostome are small in diameter, have gap and intermediate-type cell junctions within each epithelial layer and are associated with the opposite epithelial layer by transmesogleal processes and gap junctions. Nematocysts and sensory cells are aggregated in the circumoral region. The fine structure of adherent flagella arising from gastrodermal gland cells, and the transition region at the mouth between epidermis and gastrodermis are described in detail for the first time. The possible functional significance of the findings is discussed.


Morphometric estimation of stromal edema during delayed implantation in the rat.

Morphometric methods were used at the light microscopic level to investigate the appearance of edema in the endometrial stroma of rats during estradiol-induced implantation after an experimental delay. Comparisons between blastocyst-free and blastocyst-containing sites were made at 18, 12, 16 and 24 h after injection of estradiol (h.a.e.). The development of stromal edema during implantation was found to be diphasic. First, during the initial 8--12 h.a.e., a generalized edema developed all along the uterine horns. Later, from 16 h.a.e. onwards, a local edema was present around the blastocysts. The Pontamine Blue Reaction (PBR) became visible between 20 and 24 h.a.e. The results indicate that the blastocyst is recognized by the stroma considerably before the PBR. The appearance of a local edema around the blastocysts before the PBR might be related to a slow increase in vascular permeability and/or to the increased stromal cell synthetic activity that is known to precede the PBR during early implantation.


On the development of midpiece mitochondria of mouse spermatozoa.

As seen by scanning electron microscopy, the mitochondrial helix in the developing midpiece of mouse testicular spermatozoa is dextral in direction and consists of spherical mitochondrial units arranged in an orderly array of four units per gyre: three appearing in face view and a fourth hidden from view at the back of the gyre. As the spermatozoa mature, the dextral helix is transformed into a sinistral helix. Its constituent spherical mitochondria either change direction abruptly without changing shape; or having first become semilunar or diamond-shaped, they change direction gradually. Mitochondrial division follows the change in helical pitch producing a double sinistral helix. The spherical (or semilunar/diamond-shaped) mitochondria presumably elongate to form the units of the mature midpiece.


Vacuolated neurons in the hypogastric ganglion of the rat.

The vacuolated neurons (VN) of the main hypogastric ganglion of the male rat were studied using the formaldehyde-induced fluorescence (FIF) method for the histochemical demonstration of catecholamines. Microspectrofluorimetry was performed to identify the fluorophores and to quantify the FIF. The thiocholine method (Koelle-Gomori) was used to demonstrate acetylcholinesterase activity. The fine structure of the VN was studied using glutaraldehyde/OsO4 fixation. (1) In the untreated adult male rat VN represent only a small population of the total number of hypogastric neurons (0.8--1.2%). The vacuoles are similar to those of the VN from the corresponding female ganglion. (2) The VN are considered to be adrenergic due to the nature of their fluorophore, indicating a primary catecholamine. (3) The first VN appear in the hypogastric ganglia at the age of 7 weeks. After testosterone administration to young rats, VN are found at the age of 4 weeks. (4) The basic fine structure of the VN is similar to that of other ordinary neurons of the hypogastric ganglia. (5) The content of the vacuoles could not be identified. (6) Indications of degeneration were not observed in the VN. (7) The VN are interpreted as being a functional stage of the "short" adrenergic neurons, which are under the control of steroid hormones. (8) Fifteen months after castration, no VN could be found in the hypogastric ganglia, while their number was normal in the corresponding control animals.


Chloride cells and chloride exchange in the skin of a sea-water teleost, the shanny (Blennius pholis L.).

The fine structure of the skin and its importance in chloride outfluxes were investigated in a sea-water teleost, the shanny (Blennius pholis L.). The epidermis is composed of three cells types: epithelial cells, mucous cells and chloride cells. These chloride cells typically contain a great number of mitochondria and an extensive agranular reticulum extending through the whole cell body. They open at the surface of the epidermis into an apical pit. An undifferentiated small cell is often observed near these chloride cells and probably corresponds to the "adjacent chloride cell". The values of chloride outfluxes through the skin and the gills are respectively 5333+/-884 muEq.h-1.kh-1 and 4479+/-2521 muEq.h-1.kg-1; n = 6; t degrees = 13+/-0.5 degrees C. Thus the ratio between skin chloride outflux and total chloride outflux is 64.7 +/- 9.3%.


Freeze-etch study of the teleostean pituitary.

The structure of membranes in the pituitary of several teleostean species was studied with the freeze-etching technique. Nuclear pore density is higher in hormone-secreting than in stellate cells, suggesting a higher rate of nucleo-cytoplasmic interactions in the secretory cells. The perinuclear endoplasmic reticulum (ER) in the MAS-secreting cells has a large number of fenestrae, whereas in the ER whorls of the prolactin-secreting cells the fenestration occurs only rarely. Three different types of membrane specializations are described, presumably related to exo-endocytotic events at the level of the plasmalemma.


The smooth endoplasmic reticulum in neurohypophysial axons of the rat: possible involvement in transport, storage and release of neurosecretory material.

The intra-axonal organization of the smooth endoplasmic reticulum was studied in the neurohypophysis of rats during and after water deprivation. Parallel to conventional electron microscopy, the material was treated with a double impregnation staining technique specifically designed to contrast the intracellular membranous system. In conventionally stained ultrathin sections from severely dehydrated rats most axons appeared to be free of membranous organelles, whereas corresponding axons treated with the double-impregnation technique generally exhibited a highly developed system of smooth endoplasmic reticulum. In axonal endings, both techniques revealed a profusion of microvesicles in intimate relationship with tubular elements of the smooth endoplasmic reticulum. In short-term (12h) rehydrated rats, a similarly developed system of smooth endoplasmic reticulum was stilll observed at all axonal levels with both procedures. After 24 to 48 h or rehydration the tubules of the smooth endoplasmic reticulum exhibited, in double impregnated material, numerous dilatations which resembled the adjacent neurosecretory granules. In conventionally stained ultrathin sections, an accumulation of electron dense material occurred within tubules of the smooth endoplasmic reticulum in the more proximal axonal segments, while in the more terminal segments, which contained numerous elongated granules, membrane continuity was frequently observed between newly formed granules and the smooth endoplasmic reticulum. After 7 days of rehydration the general pattern of the axonal smooth endoplasmic reticulum was comparable to that in untreated rats. These results are discussed in the light of a suggested involvement of the axonal smooth endoplasmic reticulum in the non-granlular transport of neurosecretory material in connection with (1) storage in distally formed granules, and (2) release via microvesicles.


Photoreceptor membrane breakdown in the spider Dinopis: localisation of acid phosphatases.

The ultrastructural localisation of acid phosphatases (AcPhs) during the normal daily breakdown of rhabdomere membrane in Dinopis has been examined using beta-glycerophosphate and p-nitrophenyl phosphate as substrates. Results are related to the classification of organelles in the receptors given by Blest, Powell and Kao (1978). Weak and infrequent reactions are obtained in multivesicular bodies (mvbs) and multilamellar bodies (mlbs) derived from them. Residual bodies (rbs) begin to react strongly as they lyse. Source of AcPhs is endoplasmic reticulum which has barely differentiated towards the GERL configuration; it becomes reactive as it is incorporated into secondary lysosomes. GERL tubules, Y-bodies and vesicles respond erratically and weakly, and are also incorporated into rbs. No evidence was found for a significant participation of Golgi bodies in these processes, and acid phosphatase cytochemistry fails to reveal a topographical relationship between GERL in these cells and Golgi saccules. Coated vesicle clusters found in the predawn receptive segments are AcPh-negative; this implies that their previous identification as GERL-derived "Nebenkerne" carrying hydrolytic enzymes to newly-formed mvbs (Blest, Kao and Powell, 1978) is dubious. Isolation bodies and autophagic vacuoles enclosing other organelles in pathological receptors give strong reactions while adjacent secondary lysosomes derived from rhabdomere membrane and associated GERL give weak ones. It is concluded that rhabdomere-derived rb lysis is more tightly regulated than other autophagic processes, and it is suggested that a high degree of control is necessary in a receptor which may repeat the autophagy of a large mass of transductive membrane at least 60--100 times in the course of its working life.


Synaptic ribbons during postnatal development of the pineal gland in the golden hamster (Mesocricetus auratus).

Synaptic ribbons, functionally enigmatic structures of mammalian pinealocytes, were studied during the postnatal development of the pineal gland in the golden hamster (Mesocricetus auratus). On day 4 post partum, synaptic ribbons appear in cells that have already started to differentiate into pinealocytes. Between days 4 and 9, an increase in the number of synaptic ribbons occurs, concomitant with the continuing differentiation of the pineal tissue. Between days 9 and 16, when differentiation of this tissue is almost completed, the number of synaptic ribbons decreases and approaches that characteristic of the adult pineal gland. During development, the synaptic ribbons increase in length, and dense core vesicles are frequently found in the vicinity of these structures. It is assumed that a functional relationship exists between dense core vesicles and the synaptic ribbons, which are considered to be engaged in a certain form of secretory activity of the mammalian pineal gland.


Effect of estradiol-17 beta on the cytology of the liver, gonads and pituitary, and on plasma electrolytes in the female freshwater eel.

Female freshwater eels injected with estradiol-17 beta (E2) for 15--78 days appear paler and secrete more mucus than controls. The resulting strongly opalescent blood plasma indicates that vitellogenin synthesis occurs in the liver, which shows a significant hypertrophy, an increased vacuolization (lipid material) and glycogen depletion. Plasma sodium is lowered, but calcium levels are considerably increased. The gonosomatic index increases (0.92 +/- 0.1 to a maximum of 2.21). Oocytes are enlarged, but the incorporation of vitellogenin remains discrete. Gonadotrophs (GTH cells), small and scarcely visible in the pituitary of control eels, are hypertrophied and contain numerous glycoprotein granules after E2-administration. E2 may act on the pituitary and/or hypothalamus via a positive feedback to induce gonadotrophin (GTH) synthesis; GTH release seems to be very limited as indicated by the ovarian response. The differentiation of GTH cells in eels treated with fish pituitary extracts is most probably due to secretion of E2 by the ovary, which reacts on the pituitary. Various hypotheses are considered to explain the low GTH release. Thyrotrophs, somatotrophs and prolactin cells of the pituitary are stimulated. In the pars intermedia, MSH and PAS-positive cells appear less active. A possible antidopaminergic effect of E2 is discussed. E2 administration constitutes a simple and economic technique to induce the synthesis of GTH and will facilitate the biochemical and biological study of the latter hormone in eels.


Effects  of pimozide on the ultrastructure of the pars distalis in the rat.

The effects of pimozide, a dopamine receptor-blocking agent, were studied in the pars distalis of the rat. The animals received 100 micrograms/100 g pimozide daily for 5, 10, 15, and 20 days. Pimozide induces striking ultrastructural changes after 5 days of treatment. The number of luteotroph (LTH) cells is signficantly increased; they display characteristics of stimulation. The extrusion of granules into the intercellular space via exocytosis is frequently observed. The intercellular spaces are highly dilated, forming a lacunar system filled with an amorphous material, erythrocytes and involuted LTH cells. Transitional stages in the process of involution are observed in LTH cells. Luteotroph cells also form a syncytium. Twenty days after treatment the above-described changes decrease in magnitude. The present findings suggest that pimozide stimulates the mechanism of synthesis and release in the luteotroph cells, an effect that is less evident with longer treatment.


A combined horseradish peroxidase and Golgi study on the afferent connections of the ventrobasal complex of the thalamus in the cat.

Afferent connections to the ventrobasal complex (VB) of the thalamus were studied by means of retrograde transport of horseradish peroxidase (HRP) and by the Golgi-method. After HRP-injection into the VB, peroxidase-positive cells were observed contralaterally in the dorsal column nuclei (DCN), in the trigeminal nuclei and in the lateral cervical nucleus (LCN), and ipsilaterally in the somatosensoty I (SI) and II (SII) cortical areas. Labeled cells of different shape and size were compared with neurons impregnated by the Golgi-technique. On tn size and shape even within one region and that they correspond to the relay or efferent neurons observed in the Golgi-material.


Cytological changes in the pars distalis of the female rat hypophysis grafted under the kidney capsule.

Intact female rats received transplants of two hypophysial partes distales under the kidney capsule. The plasma levels of prolactin were determined, and the ultrastructure of the grafted gland was studied 15, 45 and 90 days after the operation. Although prolactin levels in the three experimental groups were significantly higher than those in control rats, a decrease in prolactin level was detected in the 45-day samples. Parallel ultrastructural changes suggest that between the 45th and 90th postoperative day a process is initiated leading to hyperplasia and hypertrophy of prolactotrophs.


Teratocarcinoma stem cells have a cell surface carbohydrate-binding component implicated in cell-cell adhesion.

Teratocarcinoma stem cells maintained in the undifferentiated state express a carbohydrate-binding component that recognizes oligomannosyl residues. This cell surface molecule is detected by a rosetta assay in which the stem cells form rosettes with glutaraldehyde-fixed trypsinized rabbit erythrocytes. Addition of simple sugars to the assay mixture has little effect, but rosette formation is inhibited by a series of mannose-rich glycoproteins (yeast invertase, yeast mannans and horseradish peroxidase). Periodate oxidation eliminates the inhibitory activity of invertase whereas pronase digestion has little effect, indicating that carbohydrate moieties are essential for inhibition. Invertase and its glycopeptide derivatives also inhibit the reaggregation of dispersed stem cells and promote the dissociation of preformed aggregates. These results suggest that intercellular adhesion of teratocarcinoma stem cels may be the consequence of the interaction of a lectin-like component detected in the rosette assay with a complementary oligosaccharide receptor on adjacent cells.


Fibronectin alters the phenotypic properties of cultured chick embryo chondroblasts.

The state of chick embryo chondroblasts in culture was found to be sensitive to both fibronectin and another substance(s) (activity A) which could be extracted from chick embryo fibroblasts with 1 M urea or from conditioned medium. In the presence of either of these activities at concentrations of 25-150 micrograms/ml, chondroblasts, which normally grow as mixed cultures of floating and adherent cells, all immediately became attached to the tissue culture dish and spread. After several days, the morphology of these typically epithelioid cells became fibroblastic. This did not involve a selection process, since the effect was reversible. The synthetic program of these cells was also dramatically modified: the cultures no longer synthesized the chondroblast-unique type IV sulfated proteoglycan and began synthesizing alpha 2 collagen chains typical of fibroblastic or early limb bud cells. Fibronectin was resolved from activity A by gelatin affinity chromatography or gel filtration. Both activities were trypsin-sensitive. The two activities differed, however, on the basis of how the protein fractions in which they were found migrated in SDS-polyacrylamide gels, their specific activities and their effects on cell morphology and cell growth.


Abnormal lipid-linked oligosaccharides in class E Thy-1-negative mutant lymphomas.

The glycosylation defect of Thy-1-mutant lymphomas of the class E complementation group has been identified as a block in the synthesis of the lipid-linked oligosaccharide precursor of the asparagine-linked oligosaccharides of glycoproteins. Two major lipid-linked oligosaccharides were isolated from the mutant cells. Both oligosaccharides were smaller than the lipid-linkid oligosaccharides of wild-type lymphomas and, in contrast to the lipid-linked oligosaccharides isolated from wild-type cells, both were resistant to digestion with endoglycosidase H. The oligosaccharides of newly synthesized polypeptides in class E Thy-1-cells were also resistant to endoglycosidase H digestion, providing strong evidence that they are derived from the abnormal lipid-linked oligosaccharides.


Export of proteins from oocytes of Xenopus laevis.

When human lymphoblastoid mRNA was microinjected into X. laevis oocytes, titers of interferon rapidly reached a maximum inside the oocyte while accumulation of interferon continued in the incubation medium for at least 45 hr. If interferon protein was injected into oocytes it was rapidly inactivated. Significantly, newly synthesized interferon but not injected interferon was found to be membrane-associated. Further experiments involving the co-injection of mRNAs coding for secretory proteins (guinea pig milk proteins and human interferon) and nonsecretory proteins (rabbit globin) revealed that only the secretory proteins were exported from the oocyte. Moreover, different proteins were exported at different rates. A distinct subclass of newly synthesized oocyte proteins of unknown function also accumulated in the incubation medium. Since the information encoded in the messenger RNAs of secretory proteins is sufficient to specify synthesis, compartmentation and secretion of these proteins, the oocyte may provide a complete system for the analysis of the secretory process.