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Biomedical subjects

M C Wilson

Publications and source records attributed to M C Wilson.

At least 145 records · Page 8Linked to original sources
PubMed1983

Reproductive toxicity of methyl-1-(butylcarbamoyl)-2-benzimidazole carbamate (benomyl) in male Wistar rats.

Methyl-1-(butylcarbamoyl)-2-benzimidazole carbamate (benomyl) is a systemic fungicide which has been implicated in producing damage to the testes. The present investigation was undertaken to evaluate the functional and behavioral significance of this reported benomyl-induced damage to male rats using a 70-day feeding study followed by a 70-day recovery study. Adult male Wistar rats were fed laboratory chow containing 1.0, 6.3, or 203 ppm benomyl, with control animals receiving standard laboratory chow. Ejaculate sperm counts were significantly depressed (P less than or equal to 0.05) in male ingesting 203 ppm benomyl during the 70 day feeding phase. A significant decrease in relative testicular weights and a lowered male fertility index were observed in all benomyl-treatment groups. No significant alterations in plasma testosterone, LH, or FSH levels were observed during the feeding phase. Benomyl ingestion did not alter male copulatory behavior, nor was benomyl found to be an inducer of dominant lethal mutations. Identical studies performed during the recovery phase demonstrated that the benomyl-induced alterations in testicular function were reversible. The male fertility index, ejaculate sperm content, and testicular weights returned to control values during this phase.

Animals↗
PubMed1983

Twin-beam laser velocimeter for the investigation of spermatozoon motility.

Previous laser light-scattering studies of spermatozoon motility have been hampered by the large, asymmetric shape of spermatozoa, which causes difficulties in the interpretation of intensity fluctuations in the light scattered from a single laser beam. This paper describes an experimental arrangement for measuring the distribution of transit times for swimming spermatozoa using two slightly separated, focused laser beams. The theory of operation of the instrument is developed to enable the analysis of the experimentally obtained cross-correlation functions. The effects of the pronounced spermatozoon asymmetry and associated intensity modulation in the scattered light are also investigated and shown to be negligible for the twin beam experimental arrangement, provided that the swimming speed distribution has a coefficient of variation (sigma/upsilon greater than 0.1. Results obtained using this apparatus are presented for the velocity distribution of spermatozoa from a variety of bulls.

Animals↗
PubMed1983

Decline in male mouse pheromone with age.

An age-related decline in urinary-borne pheromone was found in male C57BL/6J mice aged from 2 to 30 months. Pheromone activity, estimated by bioassay, declined sharply after about 10 months of age. Two other strains of mice tested (DBA/2J and CBA/HT6J) also appeared to show an age-related decline in pheromone activity. Within each strain, however, pheromone activity was consistently similar to or higher than that of the C57BL/6J male mice. The DBA/2J and BALB/cWt strains appeared to be high pheromone producers, and the C57BL/6J and CBA/HT6J strains, low producers. This report is the first demonstration of a decline with age in male mouse pheromone activity. This decline appears to be synchronized with the well-defined loss of reproductive function in female mice.

Aging↗
PubMed1982

A genetic locus regulates the expression of tissue-specific mRNAs from multiple transcription units.

129 GIX- mice, unlike animals of the congeneic partner strain GIX+, do not express significant amounts of the retroviral antigens gp70 and p30. Evidence is presented indicating that the GIX phenotype is specified by a distinct regulatory gene acting on multiple transcription units to control the levels of accumulation of specific mRNA species. The steady-state levels of retroviral-homologous mRNA from the tissues of GIX+ and GIX- mice were examined by blot hybridization using as probes DNA fragments from cloned murine leukemia viruses. RNA potentially encoding viral antigens was reduced or absent in GIX- mice, even though no differences in integrated viral genomes were detected between these congeneic strains by DNA blotting. Tissue-specific patterns of accumulation of these RNA species were detected in brain, epididymis, liver, spleen, and thymus, and several distinct RNA species were found to be coordinately regulated with the GIX phenotype. Measurements of RNA synthesis suggest a major role for transcriptional control in the regulation of some retroviral messages.

Animals↗
PubMed1981

Regulation of adenovirus-2 gene expression at the level of transcriptional termination and RNA processing.

The major late adenovirus-2 transcription unit is active early in infection at a rate equal to that of the other early transcription units. However, transcripts seem to terminate early in infection near map position 60-70 in contrast to late in infection, when termination occurs at map position 99. RNA processing, both poly(A) site selection and splicing, results in the production of a single L1 mRNA during early infection. All these processes are in contrast to those occurring late in infection, indicating that the events of transcriptional termination, poly(A) site selection and splicing can change depending on the conditions of the cell and therefore can participate in the regulation of gene expression.

Adenoviruses, Human↗
PubMed1981

Alteration of the disruptive effect of fenfluramine on food consumption in the rat by repeated post-session administration of d-amphetamine.

The purpose of this study was to determine whether repeated treatment (15 days) with d-amphetamine (AMP) or fenfluramine (FEN), administered after a daily 3 h feeding session (e.g. post-session), would result in tolerance or cross-tolerance to the decrement in food consumption induced by treatment with either drug before feeding (e.g. pre-session). Groups of males rats were treated IP with 0.5 ml saline, 1.0, 2.0, or 4.0 mg/kg AMP, or 2.5, 5.0, or 10.0 mg/kg FEN prior to a 3 h feeding session. For the next 15 sessions, the respective groups were treated post-session with saline (0.5 ml), AMP (4.0 mg/kg), or FEN (10 mg/kg). Following this 15 day post-session phase, each group again received this pre-session treatment. The initial pre-session treatment with all dosages of these two drugs produced a significant decrease in food consumption. Tolerance to the food intake suppressant effect of FEN, but not AMP, resulted from repeated post-session treatment with the same agent. Repeated post-session treatment with AMP resulted in a significant decrement in the suppressant activity of FEN on food intake, whereas the corresponding post-session treatments with FEN did not alter the pre-session effects of AMP except for an enhancement seen with higher AMP doses.

Animals↗
PubMed1981

Comparative stimulus properties of two fractions of the coca leaf (E. coca).

Male and female Wistar rats were trained to discriminate 5.0 mg/kg cocaine from 2.0 ml/kg saline using a two-bar food reinforcement (FR 30) drug discrimination paradigm. Once discrimination behavior had stabilized the subjects were tested (in extinction) with several doses of two different fractions of the coca leaf and four doses of cocaine HCl (1.0, 2.5, 7.5, 10 mg/kg). The fractions were prepared by extracting powdered coca leaves with 95% ethanol and then partitioning the residue between chloroform and water. Two doses of the water fractions (480, 960 mg/kg) and five doses of the chloroform fraction (7.5, 15, 30, 60 120 mg/kg) were tested. The water fractions was devoid of cocaine while the five doses of the chloroform fraction contained cocaine equivalent to 0.4, 0.83, 1.65, 3.3 and 6.6 mg/kg, respectively, as determined by gas chromatographic analysis. The 2.5, 7.5, and 10.0 mg/kg cocaine doses generalized to cocaine. The 1.0 mg/kg dose of cocaine generalized to saline. The water fraction at 480 mg/kg generalized to saline; however following pretreatment with the 960 mg/kg dose of this fraction, the animals failed to respond. The two largest doses of the chloroform fraction (60 and 120 mg/kg) generalized to cocaine while the other three doses did not. The 7.5 mg/kg generalized to saline; the 15 and 30 mg/kg doses engendered an intermediate level of responding on both the cocaine and saline lever.

Animals↗
PubMed1981

Discriminative stimulus properties of cocaine, norcocaine, and N-allylnorcocaine.

A discriminative stimulus paradigm was employed to train eight male and female Wistar rats to discriminate 5.0 mg/kg cocaine HCl from 2.0 ml/kg saline. Subjects responded in a two bar operant chamber on an FR 30 schedule for food reinforcement. All sessions followed a 10 minute pretreatment with either saline, the training dose of cocaine, four probe doses of cocaine HCl (1.0, 2.5, 7.5, 10 mg/kg), four probe doses of norcocaine (1.0, 2.5, 5.0, 7.5 mg/kg) or four probe doses of N-allylnorcocaine (5.0, 7.5, 10, 20 mg/kg). All probe doses were treated using an extinction procedure. The three highest doses of cocaine generalized to cocaine while the 1.0 mg/kg dose of cocaine generalized to saline. The two highest doses of norcocaine generalized to cocaine while the 2.5 mg/kg dose of norcocaine resulted in 57% responding on the cocaine lever with the 1.0 mg/kg dose generalizing to saline. Only the highest dose of N-allylnorcocaine was found to generalize to cocaine with the intermediate doses resulting in an intermediate level of responding occurring on the cocaine lever. The 5.0 mg/kg dose of N-allylnorcocaine generalized to saline.

Animals↗
PubMed1981

Large heterogeneous nuclear ribonucleic acid has three times as many 5' caps as polyadenylic acid segments, and most caps do not enter polyribosomes.

The rate of synthesis in Chinese hamster cells of 5' cap structures, m7 GpppNmp, in large (greater than 700 bases) heterogeneous nuclear ribonucleic acid (RNA) molecules is two to three times faster than the synthesis of 3'-terminal polyadenylic acid segments. As judged by presence of caps, newly synthesized polysomal messenger RNA, exclusive of messenger RNA the size of histone messenger RNA, is more than 90% in the polyadenylated category. It appears, therefore, that between half and two-thirds of the long capped heterogeneous nuclear RNA molecules do not contribute a capped polysomal derivative to the cytoplasm. There are capped, nonpolysomal, non-polyadenylated molecules with a rapid turnover rate that fractionate with the cytoplasm. These metabolically unstable molecules either could represent leakage into the cytoplasm during fractionation or could truly spend a brief time in the cytoplasm before decay.

Animals↗
PubMed1981

Chinese hamster polyadenylated messenger ribonucleic acid: relationship to non-polyadenylated sequences and relative conservation during messenger ribonucleic acid processing.

We have further analyzed the metabolism of specific messenger ribonucleic acid (mRNA) sequences within the cytoplasmic and nuclear RNA of Chinese hamster ovary (CHO) cells by using a set of previously constructed complementary deoxyribonucleic acid (DNA) clones (Harpold et al., Cell 17:1025-1035, 1979) as specific molecular probes in a variety of RNA:DNA hybridization experiments. The majority of the labeled mRNA complementary to each of the nine clones was found in the polyribosomes, with some variation between individual sequences. The great majority of each specific mRNA labeled for 3 h or less was in the polyadenylated [poly(A)+] fraction. However, the amount of each sequence increased in the non-poly(A)+ [poly(A)-] fraction after very long label times, suggesting the derivation of the poly(A)- RNA from the poly(A)+ RNA. Eight of the nine mRNA's have cytoplasmic half-lives ranging from 8 to 14 h, whereas one of the mRNA's, the scarcest in the group, has a somewhat shorter half-life of approximately 3 h. The proportion of each of the specific long-lived mRNA's within the total labeled mRNA increased as a function of labeling time, indicating that a large fraction, probably greater than 50%, of the initially labeled poly(A)+ mRNA in CHO cells has a half-life of less than 3 h. A quantitative analysis of the kinetics of labeling of specific nuclear and cytoplasmic sequences indicated that a significant fraction of the mRNA sequences transcribed from genes containing these nine CHO sequences were successfully processed into mRNA. However, two of the CHO mRNA sequences were only partially conserved during nuclear processing to yield mRNA. These studies demonstrated that events at two post-transcriptional levels, differential nuclear processing efficiency of different primary transcripts and cytoplasmic stability of different mRNA's, can be involved in the determination of the cytoplasmic concentrations of different mRNA's.

Animals↗
PubMed1980

Effects of d-amphetamine and diazepam on paired and grouped primate food competition.

Two male and two female rhesus monkeys (Macaca mulatta) were the subjects of an experiment designed to assess the effect of d-amphetamine (DA; 0.125, 0.5 and 2.0 mg/kg, IM) and diazepam (DZP; 0.5 and 2.5 mg/kg, IM) on food-getting behavior in paired and group competition. Paired competition results show that in some cases submissive animals, that had previously failed to obtain apple pieces, were successful in obtaining some apple pieces when either the dominant animal of the pair or both subjects were given 0.5 mg/kg DA or 2.5 mg/kg DZP. Results revealed the same effect when all animals (group competition) were given 0.125 and 2.0 mg/kg DA and 2.5 mg/kg DZP. These results appear to indicate that the effect of drugs on food-getting behavior in competitive situations is in some manner influenced by the social status of the animal.

Animals↗
PubMed1980

Sociopharmacology of d-amphetamine in Macaca arctoides.

This study was designed to assess the effects of acute d-amphetamine pretreatment on the social behavior of a heterosexual group of adult M. arctoides. The dominance status had been previously determined by use of daily group food competition tests. Prior to some sessions amphetamine was administered to a single group member; whereas on other occasions all subjects were drug treated. The effects of both the individual and concurrent pretreatments were compared to those produced by saline. Furthermore, the effects of individual treatment were compared to those following concurrent dosing. The behavior of the group was monitored for one hour after a fifteen minute pretreatment time. Although generally qualitatively similar, the effects of concurrent and individual treatment were in many instances quantitatively different. d-Amphetamine increased vocalization, self-grooming, playing (low doses), social grooming (low doses), and aggression (low doses). At higher doses most forms of social interaction (playing, social grooming) were greatly decreased. Presenting behavior was increased by all doses under both treatment conditions. Mounting was increased to a much lesser extent and only after concurrent dosing. The increased presenting and mounting may be a result of sexual stimulation or perhaps more likely, an indication of increased submissive behavior directed toward more dominant animals.

Aggression↗
PubMed1980

Comparative behavioral profile of cocaine and norcocaine in rats and monkeys.

The effects of cocaine and norcocaine were compared using locomotor activity, fixed-ratio 100 (FR 100) and fixed-interval 4 min (FI 4 min) food reinforcement and free feeding paradigms in rat and intravenous self-administration tests in rhesus monkeys. Cocaine was shown to significantly increase locomotor activity at doses of 20 and 40 mg/kg, while norcocaine had no effect at these doses and produced convulsions and death at 60 and 80 mg/kg. Both compounds significantly reduced food consumption at one or more of the doses tested. Cocaine and norcocaine at doses of 20 and 40 mg/kg, produced decreases in FR responding. Cocaine at doses of 10, 20, and 40 mg/kg, produced increases in FI responding; norcocaine had no effect following 10 mg/kg and decreased responding at 20 and 40 mg/kg. Cocaine (0.2 mg/kg/inj) and norcocaine (0.5, 0.2, 0.8 mg/kg/inj) maintained intravenous self-administration in all three monkeys tested. The data indicate that norcocaine is a pharmacologically active metabolite of cocaine which could account for some of the activity heretofore attributed to cocaine. However, the lack of any stimulatory effect of norcocaine or locomotor activity and the lack of increased responding produced by norcocaine on fixed-interval behavior suggest that norcocaine differs qualitatively from cocaine.

Animals↗