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Biomedical subjects

J Wolff

Publications and source records attributed to J Wolff.

At least 127 records · Page 7Linked to original sources
PubMed1990

Developmental expression of the creatine kinase isozyme system of Xenopus: maternally derived CK-IV isoform persists far beyond the degradation of its maternal mRNA and into the zygotic expression period.

The differential expression of the multilocus CK isozyme system throughout development of the two Xenopus species X. laevis and X. borealis was investigated. A cDNA containing the nearly complete coding sequence of the CK-IV subunit of X. laevis was isolated and sequenced. Early development of X. laevis proceeds with a stock of maternally derived CK-IV/IV isozyme. While the mRNA declines rapidly after fertilization and disappears before neurulation, maternal CK-IV/IV isozyme is active far beyond the onset of zygotic expression and is still detectable when tadpoles start feeding. Zygotic expression of CK-IV begins after neurulation, at stage 22/24, and seems to start simultaneously with that of another gene, CK-III. Modulation in the expression of these two genes and the appearance of two other isoforms, the CK-I and CK-II/III isozymes, take place during development in a tissue-specific manner. During metamorphosis, the CK phenotypes of eyes and skeletal musculature undergo additional changes. The final adult pattern only appears several weeks after metamorphosis. The presumed orthologous CK isozymes of X. borealis show a developmental profile similar to that of X. laevis, except that CK-II/II is equally present in oocytes and during early development, in addition to CK-IV/IV isozyme. These results show that the expression of each of the four CK genes of Xenopus is under differential developmental control.

Amino Acid Sequence↗
PubMed1990

Hyperinsulinemia in Macaca nigra: precession to obesity and/or diabetes?

A subset of Macaca nigra have been identified with elevated levels of fasting and secretory insulin. The insulin increment between 0 and 15 min in an intravenous glucose tolerance test (IV-GTT) was 511 +/- 42 microU/ml in hyperinsulinemic (HYPER) monkeys compared to 191 +/- 16 microU/ml in nondiabetic (ND) controls (p less than 0.01). Fasting insulin increased from 37 +/- 4 in ND to 57 +/- 7 microU/ml in HYPER monkeys (p = 0.02). Glucose clearance also increased from 3.87 +/- 0.18 in ND to 5.78 +/- 0.52%/min in HYPER monkeys (p less than 0.01). The acute (239 +/- 31 versus 137 +/- 19 microU/ml/min) and secondary insulin responses (542 +/- 75 versus 207 +/- 32 microU/ml/min) were significantly greater in the HYPER monkeys than in the ND controls, respectively (p less than 0.05). The rate of glucose clearance per amount of insulin secreted was diminished about 40% in both the acute and the secondary phases of HYPER monkeys (p less than 0.02). Total C-peptide secretion was two times greater in HYPER than in ND monkeys (p = 0.05). The HYPER monkeys averaged 12-20% greater weight and 41-44% greater body mass than the ND monkeys (p less than 0.05), although both groups were fed the same amount of diet and were well within nonobese limits. These Macaca nigra appear to have a functional lesion with excess insulin secretion, relatively impaired clearance of glucose, and possible insulin resistance, but no islet pathological lesion. Development toward overt diabetes might be exacerbated if obesity became a more dominant factor.

Animals↗
PubMed1989

Tubulin dimer dissociation and proteolytic accessibility.

The alpha and beta subunits of the tubulin dimer each possess a distal C-terminal subtilisin cleavage site which, when cleaved, releases an acidic, small peptide. In addition, each possesses an internal site, cleaved by trypsin in alpha and chymotrypsin in beta, which connects the amino and carboxyl structural domains. A model of the dimer is presented which suggests that the beta C-terminal subtilisin site may be more accessible in the monomer than in the dimer. Kinetics of cleavage at this site on the dimer yield straight-line plots of log (undigested fraction) versus time, from which pseudo-first-order rate constants are obtained. Temperature effects on the rate constant are due to changes in the activity of subtilisin, not to temperature-induced unfolding around this site. The rate constant is proportional to the subtilisin/tubulin ratio, whether this is varied by changing the concentration of subtilisin or of tubulin. However, if the rate constant increases due to decreasing tubulin concentration, the extrapolated zero time intercept decreases. The decrease in zero time intercept is interpreted as being due to the appearance of a rapidly digested fraction upon dilution of tubulin. The increase observed in this fast fraction with dilution of tubulin is fully reversible upon reconcentration. It is suggested that this fast fraction represents monomeric beta-tubulin and the concentration dependence of this fast fraction indicates a dissociation constant of about 1.5 X 10(-7) M.

Animals↗
PubMed1989

Modulation of invasiveness and catalytic activity of Bordetella pertussis adenylate cyclase by polycations.

Penetration of Bordetella pertussis adenylate cyclase into CHO cells was monotonically inhibited by polylysines, with a minimum degree of polymerization of greater than 6 and less than or equal to 9 to 10. Above this level, inhibitory potency per lysyl residue was independent of polymer length; 50% inhibition was obtained with 60 microM lysine monomer. Other polycations were also potent inhibitors. The adenylate cyclase itself showed a biphasic (stimulation-inhibition) response, with a similar independence of polymer length above a certain minimum. Half-maximal inhibitory concentrations for cyclic AMP accumulation corresponded to half-maximal stimulatory concentrations of poly-L-lysine for the cyclase. The inhibitory effect of polylysines on cyclic AMP accumulation was not reversed by washing or enzymatic removal of neuraminic acid. We conclude that charge-charge interactions play an important role in the penetration of B. pertussis adenylate cyclase into host cells.

Adenylyl Cyclases↗
PubMed1989

Dissociation of catalytic and invasive activities of Bordetella pertussis adenylate cyclase.

Bordetella pertussis organisms secrete adenylate cyclase, at least one form of which can invade host cells and appears to be a virulence factor. Treatment of urea extracts containing invasive cyclase of B. pertussis with trypsin, chymotrypsin, or subtilisin abolishes the ability to increase intracellular cyclic AMP levels in CHO cells (invasiveness) at concentrations that have minimal or no effects on adenylate cyclase activity. Higher protease concentrations can inhibit catalytic activity, and 1 microM calmodulin protects this catalytic activity, but not invasiveness, against proteolytic inhibition. Rabbit immunoglobulin G (IgG) fractions from antisera prepared against urea extracts inhibited invasiveness at 10-fold-lower concentrations than inhibited catalytic activity. One IgG from a rabbit immunized against a partially purified, noninvasive form of the B. pertussis adenylate cyclase inhibited catalytic activity but was ineffective against invasiveness. We conclude that these two properties of the adenylate cyclase are independent functions that reside on different domains of the same protein or on different proteins.

Adenylyl Cyclase Inhibitors↗
PubMed1989

Acute urethritis due to Neisseria meningitidis group A acquired by orogenital contact: case report.

A case of heterosexual transmission of Neisseria meningitidis group A by fellatio, which resulted in acute purulent urethritis in the male partner, is presented. The emotional impact of a mistaken diagnosis of gonococcal infection and the need to treat asymptomatic throat carriage in sexual contacts makes early recognition of meningococcal infection important in this unusual circumstance.

Acute Disease↗
PubMed1989

Deficiency of carnitine palmitoyltransferase I.

Defective activity of carnitine palmitoyltransferase I was demonstrated in fibroblasts derived from a patient with hypoketotic hypoglycemia. The level of activity observed was approximately 10% of the control mean. Oxidation of palmitate by intact fibroblasts was reduced to 5% of control values. The patient presented at age 14 months with seizures and was found to have marked hypoglycemia and no ketones in the urine. In response to fasting, she developed hypoglycemia, but the curves for acetoacetate and 3-hydroxybutyrate were flat. Administration of medium-chain triglycerides relieved the hypoglycemia and generated a brisk ketogenesis.

Acyltransferases↗
PubMed1989

[Behavior of the oxygen half-saturation value and HbF content of blood of newborn infants during blood exchange transfusion].

An evaluation of the HbF-content and the oxygen-half-saturation value took place in 15 newborn infants before, during and after an exchange transfusion. The initial HbF content decreased to 25% after the exchange transfusion with ACF-blood. The p50-value did not increase, as expected, but decreased dependent on the volume of the exchanged blood, caused by a quick loss of 2.3.-DPG in the ACD-blood within the first two days of storage. A normalization could be demonstrated 24 hours after the transfusion.

Blood Volume↗
PubMed1989

Serologic and virologic analysis of type D simian retrovirus infection in a colony of Celebes black macaques (Macaca nigra).

Celebes macaques were tested for type D simian retrovirus (SRV) infection. SRV infection was first detected in one serum sample collected during 1980. By 1983, 32 of 46 monkeys (70%) were infected. Serotyping of the SRV isolates determined that 0/26 of the isolates were SRV-1; 24/26 were SRV-2; 1/26 was SRV-5; and 1/26 could not be typed. Restriction endonuclease mapping confirmed the SRV-2C and SRV-5 isolates. In addition, two SRV-2C variants were detected.

Animals↗
PubMed1989

[Accidents in children in relation to the accident site, age and sex].

An analysis was conducted of 1,064 child accident in-patients in the county of Suhl in 1983 and of 884 child accident out-patients in the district of Schmalkalden from July 14th, 1984 to July 13th 1985. The children were 1 to 15 years old. The analysis of the sites of the accidents was carried out with regard to age and sex. Conclusions about accident prevention were drawn from the analysis.

Accident Prevention↗
PubMed1989

Retrovirus vector-mediated gene transfer into hepatocytes.

The introduction and stable expression of foreign genes in mammalian hepatocytes have recently been demonstrated by several techniques, including the use of physical approaches such as direct injection of a DNA calcium phosphate precipitate, electroporation of plasmid DNA and the exposure to liposome-erythrocyte ghost complexes as well as the biological approach of infection of primary hepatocyte cultures with retrovirus vectors. Retrovirus-mediated transduction has proven to be highly advantageous in many in vitro gene transfer studies of mammalian cells, and recent results with primary rat liver cultures have begun to define the conditions under which foreign genes can be transduced into hepatocytes in vitro. Fully differentiated hepatocytes are poorly susceptible, if at all, to infection with retroviruses, a phenomenon due at least in part to the fact that cells must undergo replication in order to retroviral integration and gene expression to occur. Hepatocytes are largely resting cells, arrested in G0. Nevertheless, primary cultures of hepatocytes are known to demonstrate a partial de-differentiation in vitro and undergo several rounds of replication. During a narrow period of time early in primary culture correlated roughly with the de-differentiation, adult hepatocytes do become susceptible to efficient infection with retrovirus vectors. In infected cells, gene expression remains relatively stable for the several week duration of the primary culture. It is not known if the restriction of virus infection in hepatocytes is a function of the state of cellular differentiation, of the availability of viral receptors or of other factors.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1988

Extracellular cAMP formation from host cell ATP by Bordetella pertussis adenylate cyclase.

The effect of exogenously added adenylate cyclase from Bordetella pertussis (strain 114) has been investigated in Y-1 mouse adrenal tumor, chinese hamster ovary (CHO) and several other cells. A partially purified adenylate cyclase was found not to enter cells but, nevertheless, produced large amounts of cAMP in the medium. We could show that this resulted from release of ATP (and not larger molecules). The ATP released by the cells could be (1) directly measured and was replenished after each change of medium; (2) was reciprocally related to the cAMP produced; and (3) was competed for by ATPases present in added serum or by hexokinase and, less effectively, by exoenzymes on the cell surface. The extent of ATP leakage varied widely between different cell lines, being marked in CHO and Y-1 adrenal cells but negligible in transformed lymphocyte lines. The uncertainty of the origin of cAMP found in media of cultured cells requires separate analysis of cell and medium cAMP and an assessment of ATP leakage.

Adenosine Triphosphate↗