Effects of insulin receptor down-regulation on hexose transport in human erythrocytes.

D-Glucose and D-galactose influx and efflux rates in human erythrocytes were studied using infinite-cis and zero-trans assay methods. It was found that insulin decreased the infinite-cis Km for both D-glucose and D-galactose influx by 44 and 56%, respectively, while the Vmax was unchanged. The Km for D-glucose efflux in the presence of insulin decreased by 47% when compared to controls, and the change in Vmax was statistically insignificant.

Differences in retention behavior between small and large molecules in ion-exchange chromatography and reversed-phase chromatography.

The retention (k') for various biomolecules was studied as a function of the mobile phase composition in reversed-phase chromatography (RPC) and ion-exchange chromatography (IEC). The "elution window" (EW) for a molecule is defined as the mobile phase composition in which 1 less than k' less than 10. The following relations were verified: (i) EW(RPC) less than EW(IEC), and (ii) EW(large Mr) less than EW(small Mr).

Resolution of the phosphotransferase enzymes of Streptococcus mutans: purification and preliminary characterization of a heat-stable phosphocarrier protein.

The sucrose phosphotransferase system of Streptococcus mutans catalyzes the phosphorylation of sucrose to sucrose-6-phosphate with concomitant translocation of this disaccharide across the cytoplasmic membrane in reactions requiring intracellular phosphoenolpyruvate. Soluble proteins released by vigorous homogenization of cells with glass beads are shown to be necessary for the phosphoenolpyruvate-dependent phosphorylation of sucrose in combination with one or more proteins that remain tightly associated with the membrane fraction. We have partially purified phosphotransferase enzyme I and have purified a heat-stable phosphocarrier protein (HPr) to apparent homogeneity, by gel filtration and ion-exchange chromatography from the soluble fraction.

Biochemical markers for alcoholism: sensitivity problems.

A panel of blood tests, purportedly markers for alcohol abuse, were examined in 543 relatively healthy alcoholics entering ambulatory rehabilitation treatment. Individual tests were too low in sensitivity: gamma-glutamyl transpeptidase was abnormally high in only 49%, then mean corpuscular volume (45%), high density lipoprotein cholesterol (HDLC) (25%), serum glutamic oxaloacetic transaminase (SGOT) (28%), and blood alcohol (21%). HDLC was of low sensitivity, generally unaffected by liver disease, and related to quantitation of recent alcohol consumed.

Traumatic rupture of the common duct in sclerosing cholangitis.

A women, 52 years, old, with Crohn's disease of the colon treated with colectomy 9 years earlier, got a blunt abdominal trauma in a car accident. At laparotomy two weeks after the accident an isolated transverse rupture of the common hepatic duct was found just below the confluence of the hepatic ducts. The rupture was successfully repaired by a direct anastomosis.

Mannitol-specific enzyme II of the bacterial phosphotransferase system. I. Properties of the purified permease.

The integral membrane protein responsible for the transport and phosphorylation of D-mannitol in Escherichia coli, the mannitol-specific Enzyme II of the phosphotransferase system (Mr = 60,000), has been purified to apparent homogeneity using a modification of a previously published procedure (Jacobson, G. R., Lee, C.

The intramembrane topography of the mannitol-specific enzyme II of the Escherichia coli phosphotransferase system.

The D-mannitol-specific Enzyme II of the phosphoenolpyruvate-dependent phosphotransferase system of Escherichia coli is an integral cytoplasmic membrane protein responsible for concomitant transport and phosphorylation of this hexitol. We have investigated the intramembrane topography of this enzyme/permease using proteases, membrane-impermeable reagents, and antibodies against the purified protein. The results of these experiments suggest that this protein spans the membrane in a single orientation with a sizeable proportion of its mass extending into the cytoplasm, but with little of the polypeptide exposed at the outside surface of the membrane.

Substrate and phospholipid specificity of the purified mannitol permease of Escherichia coli.

D-Mannitol is transported and phosphorylated by a specific enzyme II of the phosphotransferase system of Escherichia coli. This protein was purified previously in detergent solution and has been partially characterized. As one approach in understanding the structure and mechanism of this enzyme/permease, we have tested a number of sugar alcohols and their derivatives as substrates and/or inhibitors of this protein.

Detection, assessment, and diagnosis of alcoholism. Current techniques.

The need for a continuing evolution in methods of detection, assessment, and diagnosis of alcohol abuse and alcohol dependence disorders is emphasized as a necessary step toward altering the stagnating effects of several static and outdated constructs and practices which, despite their humanitarian benefits, may actually be impediments to progress in prevention and treatment. Distinctions are drawn among the purposes and techniques of detection, assessment, and diagnosis; although all three activities are vital, it is the last that must provide a logical basis for understanding causes, courses, and treatment for health problems. Thus far, there has been little genuine progress beyond simply naming the problems we attempt to treat.

Stereochemical course of the reactions catalyzed by the bacterial phosphoenolpyruvate:glucose phosphotransferase system.

The overall stereochemical course of the reactions leading to the phosphorylation of methyl alpha-D-glucopyranoside by the glucose-specific enzyme II (enzyme IIGlc) of the Escherichia coli phosphotransferase system has been investigated. With [(R)-16O,17O,18O]phosphoenolpyruvate as the phosphoryl donor and in the presence of enzyme I, HPr, and enzyme IIIGlc of the phosphotransferase system, membranes from E. coli containing enzyme IIGlc catalyzed the formation of methyl alpha-D-glucopyranoside 6-phosphate with overall inversion of the configuration at phosphorus (with respect to phosphoenolpyruvate).

Substance-use disorders: issues in returning to practice.

Physicians recovering from substance-use disorders face many reintegration problems when they attempt to resume professional activities. Armed with state-of-the-art information, hospital medical staffs and administrators can ensure that the process is as smooth as possible and that the recovering physician's, the patient's, and the hospital's rights are protected.

Auditory dysfunction following a gunshot wound of the pons.

A patient with a gunshot wound penetrating the right side of the brainstem at the level of the pons was given a test battery to evaluate peripheral hearing function and central auditory processing abilities. A month later, the left ear had a loss of sensitivity for high frequency tones, decreased speech discrimination, and excess tone decay. Two years later these deficits had resolved.

Edema and vascular permeability in cerebral ischemia: comparison between ischemic neuronal damage and infarction.

The respective influences of ischemic neuronal damage and infarction on the development of abnormal blood-brain barrier (BBB) permeability and cerebral edema were evaluated in a rat model of temporary four-vessel occlusion in which ischemic neuronal damage with only infrequent infarction is produced. Survival times ranged from 40 minutes to 5 days after ischemia. Evans blue and horseradish peroxidase (HRP) were given before sacrifice.

Treating substance-use disorders among physicians.

Of 40 participants of a two-year program for rehabilitating alcohol- and other-drug-dependent physicians, 15 have completed 24 months of treatment and monitoring, eight have completed 12 to 23 months, ten have completed one to 11 months, and seven discontinued treatment before completion. Of the 33 treated physicians, 31 have returned to full practice and 22 have experienced no relapse. The prognosis is quite favorable for most impaired physicians in appropriate treatment, monitoring, and follow-up are provided.

Radiologic assessment of resectability of carcinoma of the head of the pancreas.

Twenty-four patients with probably resectable carcinoma of the head of the pancreas were examined by means of CT, ERCP and US and supplemented with angiography to assess the resectability. Resection was possible in half of the patients. As the series consisted only of potentially resectable cases, those with obvious liver metastases at CT or US were not included.

Plasmid-directed synthesis of enzymes required for D-mannitol transport and utilization in Escherichia coli.

A transformant Escherichia coli colony bank [Clarke, L. & Carbon, J. (1976) Cell 9, 91-99] has been screened for hybrid ColE1 plasmids carrying the genes for D-mannitol utilization.

Human thyroid blood flow response to endogenous, exogenous human, and bovine thyrotrophin measured by electromagnetic flowmetry.

Human thyroid blood flow (TBF) was studied with electromagnetic flowmetry during operation. Measurements were made of the effect on TBF of injections of bovine TSH into one inferior thyroid artery in 6 patients; 6 other patients were given human TSH, and in 10 patients measurements were made both of TBF and endogenous TSH released after administration of TRH in a peripheral vein. The TBF increased after all three types of injection.

The contingent negative variation as an indicator of speech discrimination difficulty.

Recent studies have illustrated the usefulness of the contingent negative variation (CNV) in exploring language processing capabilities. The purpose of this study was to investigate how CNV magnitude is influenced by speech discrimination tasks of graded difficulty. Nine young adult subjects performed easy and difficult speech discrimination tasks while cortical activity was recorded from the vertex.