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Biomedical subjects

H Falter

Publications and source records attributed to H Falter.

At least 19 recordsLinked to original sources
PubMed1994

Effects of tetrodotoxin-induced neural inactivation on single muscle fiber metabolic enzymes.

Selected enzymes were measured in mixed-fiber bundles and individual fibers from rat plantaris (PL) and soleus (Sol) muscles that had undergone either 2 wk of tetrodotoxin (TTX) inactivation of the sciatic nerve, a sham operation, or were contralateral to the TTX limb. TTX disuse caused severe wasting of PL (46%) and Sol (26%) muscles and of single fibers (50% and 40%, respectively). TTX PL and Sol also had reduced (50%) glycogen content. In TTX, PL, and Sol macro samples and single fibers, the activities (mol.h-1.kg dry wt-1) of hexokinase, glycogen phosphorylase, and lactate dehydrogenase were higher, lower, and unchanged, respectively, compared with controls. Single-fiber data showed that these changes occurred in all fibers. In TTX PL macro samples, activities of glycerol-3-phosphate dehydrogenase (GPDH), pyruvate kinase (PK), malate dehydrogenase (MDH), citrate synthase (CS), beta-hydroxyacyl-CoA dehydrogenase (BOAC), and thiolase were, or tended to be, lower. Single-fiber data showed a disappearance of high-oxidative moderate glycolytic fibers (i.e., usually fast-twitch oxidative in control) and the appearance of more fibers with a metabolic enzyme profile approaching that of control slow-oxidative fibers. In TTX Sol macro samples, GPDH and PK tended to be higher, and thiolase, BOAC, CS, and MDH lower. Single-fiber data corroborated these findings and suggested the appearance of fast fibers with downregulated oxidative enzyme profiles. Our results suggest that neuromuscular activity is a major, but not the sole, determinant of the size and metabolic heterogeneity that exists in muscle cells.

Animals↗
PubMed1993

Behaviors of rats with insidious, multifocal brain damage induced by seizures following single peripheral injections of lithium and pilocarpine.

Several domains of behavior were measured in rats (n = 465) 10 days to 100 days after induction of limbic seizures by a single subcutaneous injection of lithium and pilocarpine. These rats displayed enhanced intragroup aggression but normal muricide; gustatory neophobia and conditioned taste aversion were virtually eliminated. Severe working and reference memory deficits were evident within the radial arm maze. Both state-dependent memory and possible situation-dependent precipitation of spontaneous seizures were suggested. The behavioral changes were considered commensurate with the multifocal pattern of thalamic, hippocampal/amygdaloid, and limbic cortical damage.

Acetylcholine↗
PubMed1992

Gallium toxicity and adaptation in Pseudomonas fluorescens.

When cultured in a defined citrate medium supplemented with 1 mM gallium (III) Pseudomonas fluorescens ATCC 13525 experienced a lag phase of 40 h with no apparent diminution in cellular yield. Following initial uptake of the metal-ligand complex, gallium was secreted in the spent fluid. This lag phase was abolished either by inoculating the medium with gallium adapted cells or by inclusion of iron (III) (20 microM) in the growth medium. In the culture enriched with both gallium and iron (III), X-ray fluorescence spectra revealed a gradual decrease of gallium from the spent fluid as growth progressed. In a phosphate deficient medium, no cellular multiplication was observed in the presence of gallium. The inhibitory influence mediated by the trivalent metal was reversed by the addition of (20 microM) iron (III). Although bacterial growth was accompanied by an initial decrease in exocellular gallium, a marked increment in the concentration of this metal was observed in the spent fluid at stationary phase of growth. Citrate was not detected in the exocellular fluid at cessation of bacterial multiplication. Electrophoretic analyses revealed numerous variations in the cytoplasmic protein profiles of the control and metal stressed cells. Gallium induced the syntheses of polypeptides with apparent molecular masses of 89 kDa, 50 kDa, 39 kDa, 26 kDa and 12 kDa.

Adaptation, Biological↗
PubMed1992

Transient suppression of a secondary humoral response in rats is evoked by lithium-pilocarpine-induced limbic seizures.

Several experiments were designed to evaluate a secondary humoral response following limbic seizures. After baseline antigen binding capacity (ABC) had been determined for the primary response, a second subcutaneous injection of the antigen (human serum albumin) was accompanied by an injection of either lithium (3 mEq/kg)-pilocarpine (30 mg/kg) or one of two comparator treatments: metrazol (30 mg/kg) or cyclophosphamide (50 mg/kg); other rats served as drug controls. Only the groups that received the lithium-pilocarpine (status epilepticus) or cyclophosphamide (no seizure) displayed significant immunosuppression after 5 but not 10 days. The results support the hypothesis that seizure activity within the amygdaloid-hippocampal complex modulates immunocompetence through corticotropin mechanisms.

Adrenocorticotropic Hormone↗
PubMed1992

Infantile stimulation produces mild enhancement in a primary humoral response of adult albino rats.

Rat pups from 12 litters were handled daily, once every three days, or never touched between postnatal Days 5 and 20. At 100 days of age, 20 days after inoculation with human serum albumin, trunk blood was obtained to measure the antigen binding capacity (ABC). Rats handled as infants displayed relative immunofacilitation compared to those that had not been handled; the effect explained 7% of the variance in ABC values. In comparison, sex differences explained 14% of the variance. The results support the hypothesis that early disruptions in mother-infant bonding increase the likelihood of developing allergic responses following exposure to novel antigens during adulthood.

Animals↗
PubMed1991

Humoral (immunological) responses in female albino rats during rotating magnetic field exposures.

Experiments were designed to evaluate the primary and secondary humoral responses to a rotating magnetic field configuration, which is known to evoke significant biobehavioral changes. Ten days after inoculation with human serum albumin and 10 days before a booster, female rats were exposed to either a 0.5 Hz rotating magnetic field (RMF) or to room conditions (control). The lighting schedule was either continuous or involved a light-dark cycle (LD) of 12:12 h. A third group of rats served as colony room controls. Group differences of low statistical significance were found when females were exposed to continuous lighting rather than the LD 12:12 light-dark cycle. However, the effects were considered trivial and not sufficient to explain the previously reported biobehavioral changes evoked by this field configuration.

Animals↗
PubMed1991

Sex differences in primary humoral responses of albino rats to human serum albumin.

Primary humoral responses to human serum albumin, with or without concomitant Freund's adjuvant, were determined for over 300 male and female Wistar albino rats. Groups of female rats always displayed significantly more antibody production than males. Without adjuvant only 70% of the males responded compared to 99% of the females. When the antigen was accompanied by adjuvant, more than 95% of both sexes responded. Whereas without adjuvant the female response was only twice that of the males, adjuvant facilitated the response to a factor of 10 greater than the males. Both the gender and adjuvant effect each accounted for about 16% of the variance in the measurements of antigen binding capacity. Post-weaning castration did not stimulate the gender differences; there were no group differences in ABC at the extremes of estrus-related ambulatory cycles.

Adjuvants, Immunologic↗
PubMed1990

Modifications to commercial oxalate oxidase based determination of urinary oxalate: a method suitable for routine clinical analysis.

A commercially available assay (Sigma) for urinary oxalates based on the oxalate oxidase/peroxidase catalyzed reaction produced, in our hands, recoveries of added oxalate that varied from patient to patient. A modification of the assay is reported that involves the chromatographic separation of interfering substances, such as ascorbate and uric acid, from oxalate prior to analysis. With the modification recoveries of added oxalate were essentially complete and showed less patient-to-patient variability. Correlation with an alternate procedure was greatly improved.

Humans↗
PubMed1987

Isolation and purification of creatine kinase conversion factor from human serum and its identification as carboxypeptidase N.

Creatine kinase conversion factor has been isolated from human serum and purified to electrophoretic and chromatographic homogeneity. The enzyme sequentially converts creatine kinase MM3 to MM2 and MM1 and hydrolyzes lysine and arginine from hippuryl-L-lysine and hippuryl-L-arginine. Data on molecular weight, (316,000 dalton), electrophoretic mobility (alpha-globulin), prevalence in serum (26 mg/L), subunit composition (two subunits, 80,000 and 52,200 dalton) indicate that creatine kinase conversion factor is identical to carboxypeptidase N. The previously reported lower molecular weight of 190,000 dalton of partially purified creatine kinase conversion factor is attributed to proteolytic degradation.

Carboxypeptidases↗
PubMed1982

An assay for creatine kinase conversion factor.

The M subunits of creatine kinase (CK) isoenzymes, MM and MB, are subject to a postsynthetic modification in serum. As a result of this modification three sub-bands of MM can be identified by agarose electrophoresis, called MM3, MM2 and MM1 in the order of increasing electrophoretic mobility towards the anode. An assay has been developed for the protein, called creatine kinase conversion factor, which catalyses the reaction leading to the sub-bands. The assay is based on the rate of conversion of MM3 to MM2 and MM1. The first order rate constant for the conversion, designated as kc, for sera of 24 apparently healthy adults ranges from 0.0221 to 0.0740 hr-1 with a mean of 0.0392 hr-1 under the conditions of the assay. Temperature and pH dependence of kc have been determined.

Adult↗
PubMed1981

Studies on the sub-banding of creatine kinase MM and the "CK conversion factor".

In serum, the M subunit of creatine kinase (CK) isoenzymes, MM and MB, is modified by a heat labile factor. As a result of the modification three sub-bands of MM and two of MB can be demonstrated by agarose electrophoresis. Normal sera contain MM1 as the dominant sub-band with lesser amounts of MM2 and MM3. Following tissue damage the MM sub-band distribution changes as a result of the increased release of MM, which occurs as MM3. Immediately after coronary bypass surgery MM3 is the dominant sub-band to be replaced by MM2 and in turn by MM1. The factor responsible for the modification of the M subunit, the "CK conversion factor" has been partially purified and its molecular weight determined.

Biological Products↗
PubMed1976

Oral taurine effects on inhibitory behavior: response transients to step-like schedule changes.

Rats habituated to DRL 6-s schedules that required response inhibition in order to obtain reward did not alter their total responses or efficiency ratios (response/reinforcement) when placed ad libitum (orally) on 0.9% taurine (1.1 +/- 0.4 g/kg/24-h) relative to controls. In three separate experiments, taurine-administerd rats did show significantly poorer adjustment profiles (higher response/reinforcement ratios) during the 15 min immediately following step-like increases in inhibition time demand to DRL 12 s. The effect was transient and was not signficant in subsequent sessions. Taurine rats had been habituated to a DRL schedule intended to induce "frustration" before and step-change did not differ from the taurine group maintained on the normal DRL schedule. No significant differences were noted between taurine and control groups, either before or after taurine administration or before or after the step-change in inhibition demand, with respect to defecation in the test chamber, daily fluid consumption, body weight or total responses. We concluded that oral taurine may inhibit learning during labile periods of adjustment following sudden changes of input demand but does not influence a well learned or established response pattern. These results imply taurine's role in the brain as a "stabilizer" against short-term input fluctuations.

Animals↗
PubMed1976

Weak inhibitory behavioral effects of postnatal! preweaning taurine injections in rats.

The behavior of rats injected once every 2 days between Postnatal Days 4 and 20 with 62.5 mug/g or 125 mug/g body weight of taurine was compared with saline- or .5 M NaCl-injected litter-mate controls. Taurine-injected rats ran significantly less in the running wheel test and displayed lower response/reinforcement ratios following step-like changes in DRL reinforcement schedules. The quicker adjustments to the changes in DRL schedules did not occur immediately but during sessions following the change. We concluded that taurine administration during early juvenile development could weakly influence adult inhibitory behavior.

Animals↗