Regional cerebral glucose transport in insulin-dependent diabetic patients studied using [11C]3-O-methyl-D-glucose and positron emission tomography

Regional cerebral [11C]3-O-methyl-D-glucose ([11C]MeG) uptake kinetics have been measured in five insulin-dependent diabetic patients and four normal controls using positron emission tomography (PET). Concomitant measurement of regional cerebral blood volume and CBF enabled corrections for the presence of intravascular [11C]MeG signal in cerebral regions of interest to be carried out, and regional cerebral [11C]MeG unidirectional extraction fractions to be computed. Four of the five diabetic subjects were studied with their fasting plasma glucose level clamped at a normoglycaemic level (4 mM), and four were studied at hyperglycaemic plasma glucose levels (mean 13 mM). The four diabetic subjects whose fasting plasma glucose levels were clamped at a normoglycaemic level of 4 mM had mean fasting whole-brain, cortical, and white matter [11C]MeG extraction fractions of 15, 15, and 16%, respectively, values similar to those found for the four normal controls (whole brain, 14%; cortex, 13%; white matter, 17%). Mean regional cerebral [11C]MeG extraction fractions were significantly reduced in diabetic subjects during hyperglycaemia whether their plasma insulin levels were undetectable or whether they were raised by continuous intravenous insulin infusion. Such a reduction in [11C]MeG extraction under hyperglycaemic conditions can be explained entirely in terms of increased competition between [11C]MeG and D-glucose for the passive facilitated transport carrier system for hexoses across the blood-brain barrier (BBB). It is concluded that the number and affinity of D-glucose carriers present in the BBB are within normal limits in treated insulin-dependent diabetic subjects. In addition, insulin appears to have no effect on the transport of D-glucose across the BBB.     

Possible involvement of prostaglandin endoperoxides in cartilage-synovial interactions

The depletion of proteoglycans in cartilage matrix is the beginning of cartilage breakdown. Prostaglandins and related compounds might play an important role in inhibition of cartilage metabolism under arthritic conditions. Prostaglandin endoperoxides, intermediate metabolites of arachidonic acid, are more potent chemical mediators than prostaglandins, but their action can only be demonstrated in cartilage co-incubated with synovial tissue, because they are short-lived and active only within a small restricted space. Human rheumatoid synovialis highly inhibited sulfation of cartilage matrix co-incubated. The inhibition of cartilage metabolism was released by indomethacin added to the co-incubating system, showing its responsiveness to indomethacin. The magnitude of inhibition was time-dependent and substantially greater than that by prostaglandin in cell-free rheumatoid synovial culture media. The results suggest a possible involvement of prostaglandin endoperoxides in potent inhibition of cartilage metabolism under arthritic conditions.     

Mobile intraventricular cyst of the third ventricle treated with stereotactic puncture. Report of a case

A case of a pedunculated arachnoid cyst within the third ventricle is presented. The cyst was small so as not to appear as a significant expanding lesion on CT. The clinical history, however, suggested intermittent increase of the intracranial pressure. On CT there was some widening of the lateral and third ventricles, while the fourth ventricle had normal width. This finding in combination with the clinical history prompted further neuroradiologic examinations, including pneumoencephalography and ventriculography. The presence of a pedunculated mobile cystic lesion within the third ventricle was shown and its nature further elucidated by stereotactic puncture combined with contrast injection into the cyst. After emptying of the cyst, the patient has been free of symptoms during an observation time of 2 years. The diagnostic and differential diagnostic aspects are discussed and the value of traditional neuroradiologic methods emphasized.     

Flow requirements for the Bain breathing circuit during anaesthesia for caesarean section

We studied the relationship between arterial carbon dioxide tension (PaCO2) and fresh gas flow (FGF) during use of the Bain breathing circuit for Caesarean section anaesthesia. Thirty-one patients undergoing Caesarean section were anaesthetised using the Bain circuit with intermittent positive pressure ventilation. The PaCO2 were measured at FGF of 70 ml X kg-1 X min-1, 80 ml X kg-1 X min-1, and 100 ml X kg-1 X min-1. The FGF requirement to maintain a given PaCO2 during Caesarean section anaesthesia is the same as the requirements for nonpregnant subjects, despite the increase in carbon dioxide production associated with pregnancy. This is probably because the total FGF determined by body weight and given during Caesarean section anaesthesia is 15-20 per cent higher than nonpregnant levels, due to the weight gain associated with pregnancy. A FGF of 100 ml X kg-1 of pregnant weight/min maintains PaCO2 of 4.44 kPa predelivery, which is in the desirable range of PaCO2 during Caesarean section.     

Computerized tomography diagnosis of diffuse intraperitoneal metastases after retroperitoneal lymphadenectomy for testicular carcinoma

We report 2 cases of diffuse intraperitoneal metastases from testicular carcinoma following transabdominal retroperitoneal lymphadenectomy. This is an unusual pattern of metastasis for nonseminomatous germ cell tumors and it is believed to be the result of direct seeding from lymphatic leakage secondary to surgery. The value of computerized tomography in diagnosing this entity is emphasized.     

Premenstrual syndrome in Cape Town. Part I. An analysis of 100 consecutive patients

One hundred consecutive patients who attended the premenstrual syndrome clinics at Groote Schuur and Somerset Hospitals were analysed. The incidence did not correlate with age, marital status or parity. Seventy per cent of patients were employed or were full-time students, and 72% had a regular menstrual pattern. The commonest symptoms were irritability, depression and abdominal bloating.     

The clinical efficiency of the Portex in-line blood warmer

The Portex blood warming coil (200/700/000) and water bath (500/111/010) were tested by comparing the body temperatures of two groups of patients undergoing similar operations, but having transfusions of different rate and quantity. The skin and oesophageal temperatures in the massively transfused patients (5-31 units) did not differ significantly from those having minor transfusions (1-5 units). The temperatures were well maintained in both groups. The lowest mean oesophageal temperatures, during the transfusions, were 35.2 +/- 0.2 in the massively transfused patients and 35.4 +/- 0.1 (SEM) in the control group. The warming capacity of the Portex blood warmer was therefore sufficient for our patients. If, however, transfusion rates, higher than those in this study (maximum 96 ml min-1 during the rapid transfusion phase) are needed, a more effective blood warmer may be beneficial.     

Phorbol 12-myristate 13-acetate induces beta-adrenergic receptor uncoupling and non-specific desensitization of adenylate cyclase in human mononuclear leukocytes

Tumour-promoting phorbol esters such as phorbol 12-myristate 13-acetate (PMA) have been reported to modulate beta-adrenergic receptor responses in various cell types, presumably by the activation of protein kinase C. In the present investigation we assessed the effect of PMA on the beta-adrenergic receptor-adenylate cyclase system of human mononuclear leukocytes (MNL). It was found that incubation of MNL with PMA resulted in a time- and concentration-dependent desensitization of isoproterenol-induced adenylate cyclase activity. However, the effect of PMA was not restricted to the beta-adrenergic receptor system, since basal adenylate cyclase activity and histamine-, prostaglandin E1-, 5'-guanylylimidodiphosphate (GppNHp)-, and NaF-stimulated values were also reduced. By contrast, no effect was found on the forskolin-induced adenylate cyclase activity. The inactive phorbol ester, 4 alpha-phorbol 12,13-didecanoate had no effect on adenylate cyclase at all, suggesting that the observed PMA effect was specifically mediated by activation of protein kinase C. The reduced beta-adrenergic response induced by PMA was not associated with a reduced beta-adrenergic receptor number, indicating uncoupling of this receptor from adenylate cyclase. Isoproterenol competition curves for 3H-dihydroalprenolol binding to membranes from untreated and PMA-treated cells demonstrated that the uncoupling was due to a reduced ability of the agonist to promote formation of the guanine nucleotide-sensitive high affinity state of the receptor. The results indicate that PMA may cause desensitization of catecholamine-responsive adenylate cyclase in MNL, and that the major locus of alteration is the guanine nucleotide regulatory protein.     

Vitamin D3 derivatives inhibit the differentiation of Friend erythroleukemia cells

A number of vitamin D3 metabolites inhibit benzodiazepine- and dimethyl sulfoxide-induced differentiation of Friend erythroleukemia cells. The inhibition is dose dependent and occurs at nM concentrations. The order of potency of these compounds is 1,25-dihydroxycholecalciferol greater than 1,25,26-trihydroxycholecalciferol greater than 1,24R,25-trihydroxycholecalciferol greater than 1 alpha-hydroxycholecalciferol greater than 24R,25-dihydroxycholecalciferol greater than 25S,26-dihydroxycholecalciferol. The inhibition is maximal when the vitamin D3 analogs are added together with the inducer, and becomes progressively decreased with delayed addition. These results suggest that the vitamin D3 metabolites may play a regulatory role in erythropoiesis.