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Biomedical subjects

R D Cohen

Publications and source records attributed to R D Cohen.

At least 145 records · Page 8Linked to original sources
PubMed1981

The effect of combined ischaemia and acidosis on lactate uptake and gluconeogenesis in the perfused rat liver.

1. Perfused rat livers were subjected to an acid perfusate and varying degrees of ischaemia in an attempt to simulate the conditions of strenuous exercise or shock. 2. Lactate uptake and glucose output from the liver decreased during moderate ischaemia alone and more so when, in addition, the perfusate was made acidic. 3. Hepatic ATP and ADP content increased in the presence of an acid perfusate. 4. It is concluded that both ischaemia and acidosis may contribute to the diminished hepatic uptake of lactic acid in strenuous exercise and shock.

Acidosis↗
PubMed1981

The effect of adrenaline on hepatic lactate uptake in the acidotic partially ischaemic rat liver.

1. The effect of adrenaline (7 X 10(-8) and 7 X 10(-7) mol/l) on lactate uptake and glucose output was studied in the perfused liver of starved rats under conditions of reduced flow and acid perfusate. 2. Adrenaline largely prevented the decrease in hepatic lactate uptake which would otherwise occur owing to reduced blood flow and acidosis and may, therefore, have a protective effect in strenuous exercise and shock.

Acidosis↗
PubMed1981

Effects of myocardial ischemia on quantitative ultrasonic backscatter and identification of responsible determinants.

Quantitative characterization of myocardial properties represent a rapidly emerging area of echocardiographic investigation. Because measurement of the ultrasonic integrated backscatter is theoretically applicable to analysis in vivo with reflected ultrasound, this study was performed to develop and evaluate a suitable method for measurement of quantitative backscatter in vivo. In view of the desirability of characterizing ischemic myocardium noninvasively, the study was performed with animal preparations simulating myocardial ischemia in humans. In one series of open-chest dogs, integrated backscatter among 22 ischemic regions was increased by 200% (P less than 0.01) compared to values in control regions within 1 hour after coronary occlusion and by 400% (-45.1 +/- 0.7 dB compared to -50.9 +/- 0.4 dB) (P less than 0.001) within 6 hours. In a second series of open-chest dogs, ischemia was quantified with 141Ce microspheres, and mean integrated backscatter was found to increase (280% of control) (P less than 0.01) in regions with flow less than 20% of control 2 hours following coronary occlusion. Additional studies with perfused hearts revealed two determinants of the increased ultrasonic backscatter observed: (1) an increase in cardiac fluid content reflected by the wet-to-dry weight ratio, and (2) the contributions of formed elements in whole blood. The results indicate that ultrasonic integrated backscatter distinguishes severely ischemic from nonischemic myocardium in vivo in open-chest animals. Because it was possible to obtain these results in the reflection mode, potential extension of the approach to clinical applications is promising.

Animals↗
PubMed1980

Effect of conjugated and unconjugated hyperbilirubinaemia on the plasma 25-hydroxy-vitamin D response to ultraviolet radiation in the rat.

1. Vitamin D deficiency was induced in anicteric Wistar rats, Wistar rats before common bile-duct ligation was performed and Gunn rats with unconjugated hyperbilirubinaemia. 2. The effect of ultraviolet radiation on plasma concentrations of 25-hydroxy-vitamin D was studied in a group of control anicteric Wistar rats (n = 11), Wistar rats 8 days after common bile-duct ligation (n = 7) with conjugated hyperbilirubinaemia and in Gunn rats (n = 11). 3. The plasma 25-hydroxy-vitamin D response to ultraviolet radiation was similar in the three groups. 4. It is suggested that neither conjugated nor unconjugated hyperbilirubinaemia prevent cutaneous vitamin D3 synthesis or 25-hydroxylation in the rat.

Animals↗
PubMed1980

Clinical features, prognosis, and response to treatment in polyarteritis.

Fifty-three patients with polyarteritis who were followed up for at least 2 years were defined clinically and studied retrospectively to determine the influence of clinical factors and treatment on the prognosis. There was a spectrum of severity of disease, and the 5-year survival in the group was 55%. A small number of patients had evidence of ongoing immune-complex disease, as indicated by the presence of cryoglobulins or hepatitis Bs antigen or by diminished serum complement. These markers were not associated with distinct clinical features and did not influence prognosis. Organ involvement that most adversely affected prognosis was that of the gut and the kidneys. Six of 8 patients with bowel infarction or serious gastrointestinal bleeding died, and 6 of 10 patients with renal insufficiency died. Hypertension and peripheral neuropathy did not influence the prognosis. Thirty-six patients were treated with corticosteroids alone and 14 with a combination of corticosteroids and cytotoxic agents (3 received no treatment); the outcome was the same in both groups. Twenty-two in the steroid-alone group and six in the combination group were alive when last seen. Early deaths were usually due to complications directly related to the vasculitis, and late deaths were often due to cerebrovascular or cardiovascular complications. At the last follow-up, 18 patients were in remission, and 13 had inactive vasculitic disease and were on maintenance treatment.

Adolescent↗
PubMed1979

The effect of reduction of perfusion rate on lactate and oxygen uptake, glucose output and energy supply in the isolated perfused liver of starved rats.

1. Lactate and O2 uptake and glucose output were studied in isolated livers from starved rats at perfusate flow rates varying from 100 to 7% of "normal" (11.25-0.75 ml/min per 100 g body wt.). 2. With moderate diminution of flow rate, lactate and oxygen uptake fell more slowly than would be expected if uptake purely depended on substrate supply. 3. Use of a mathematical model suggests that the intrinsic capacity of the liver for lactate uptake is unaffected until the flow rate falls below 25% of "normal". 4. Some lactate uptake was always observed even at 7% of the "normal" flow rate. 5. At flow rates below 33% of the "normal", lactate was increasingly metabolized by pathways other than gluconeogenesis, which became a progressively less important consumer of available O2. 6. ATP content decreased with diminution of flow rate, but substantially less markedly than did lactate uptake and glucose output. 7. Intracellular pH fell from a mean value of 7.25 at "normal" flow rate to 7.03 at 7% of the "normal" flow rate.

Adenine Nucleotides↗
PubMed1979

Steroids and bag and mask ventilation in the treatment of acute epiglottitis.

A non-instrumentation treatment protocol for acute epiglottitis that features the use of dexamethasone to reduce edema and positive pressure ventilation by bag and mark to support ventilation, if needed, has been used in 40 cases, 1974--1977, with no mortality. The presence of the airway specialist (pediatric surgeon) in the Intensive Care Unit with the patient further assured the airway. The importance of having a protocol in place that is workable for the specific local circumstances of each institution is emphasized.

Child, Preschool↗
PubMed1979

Anatomic observations and etiologic and surgical considerations in choledochal cyst.

Twenty-five operative and postoperative cholangiograms in children with choledochal cysts indicated an intimate relationship between these cysts and anomalous pancreatico-biliary ductal junction. In all of these patients the distal main pancreatic duct (MPD) is excluded from the sphinctor of Oddi mechanism and free reflux of pancreatic juice up the biliary tree occurs. This leads to chronic cholangitis, which is presumed to be responsible for the formation of the choledochal cysts. Abrupt and intense exposure of the common bile duct (CBD) to pancreatic reflux may cause perforation and bile peritonitis. Long-standing exposure may induce malignant transformation in the choledochal cyst. Total cyst excision and separation of the biliary system from exposure to pancreatic reflux is suggested as the procedure of choice. Long-term results and metabolic and digestive consequences of this operation are yet to be determined.

Cholangiography↗
PubMed1979

Ectopic single ureter and severe renal dysplasia: an unusual presentation.

An ectopic single ureter in the male subject is a rare anomaly, which commonly drains a dysplastic kidney to the prostatic urethra or the seminal vesicle. The further the ureteral orifice is located from the trigone of the bladder, the more severe is the ipsilateral renal dysplasia. A case is described in which an ectopic ureter and ectopic and dysplastic kidney were found at the time of inguinal herniorrhaphy. The ureter was connected to the epididymis of the testicle. This is the most severe form of ureteral ectopia and it has not been reported previously.

Abnormalities, Multiple↗
PubMed1979

Metabolism of intravenously administered cholecalciferol in man.

Following intravenous injection of (3H) cholecalciferol into healthy subjects the disappearance of label from the plasma was followed by the reappearance ("rebound") of (3H) radioactivity associated exclusively with cholecalciferol. Lipoprotein fractionation of plasma revealed an increasing association of label with protein rather than lipoprotein during the rebound phase. We conclude that the rebound of plasma radioactivity reflects the transfer of label from lipoprotein to Vitamin D-binding globulin in the liver followed by its release into plasma.

Adolescent↗
PubMed1978

Response of plasma-25-hydroxyvitamin D to ultraviolet irradiation in long-stay geriatric patients.

The response of plasma-25-hydroxyvitamin D (25[OH]D) to different exposures to ultraviolet irradiation has been studied in patients in long-stay geriatric wards. Increases sufficient to bring the plasma-25(OH)D into the normal range may be obtained with doses less than those required to produce erythema. The provision of such background irradiation may be a suitable method of preventing vitamin-D deficiency in elderly subjects who receive very little exposure to sunlight.

Age Factors↗
PubMed1978

Effect of varying PCO2 on intracellular pH and lactate consumption in the isolated perfused rat liver.

1. The effects of varying PCO2 on lactate uptake and intracellular pH (pHi) were studied in the isolated rat liver perfused with differing concentration of lactate. 2. In general, pHi and lactate uptake are inversely related to PCO2, and pHi and lactate uptake are directly related to each other, but the quantitative aspects and significance of these relationships vary with the availability of lactate. A model of hepatic lactate metabolism is proposed which may account for the quantitative variation. 3. The metabolism of lactate within the hepatocyte exerts a destabilizing effect on hepatocyte cell pH, in contrast to the buffering effect seen in predominantly glycolytic tissues. 4. An attempt is made to relate the findings to the disturbances of lactate metabolism in clinical respiratory failure.

Animals↗