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Biomedical subjects

G C Smith

Publications and source records attributed to G C Smith.

At least 307 records · Page 17Linked to original sources
PubMed1982

Effect of aluminum chloride and zinc sulfate on Autographa california nuclear polyhedrosis virus (ACNPV) replication in cell culture.

When IPL-SF-21AE III continuous insect cell line was grown and maintained in IPL-41 insect cell culture medium supplemented with 16 microM of AlCl3 or 0.24 microM of ZnSO4 . 7H2O, or both metallic salts, and then infected with Autographa california nuclear polyhedrosis virus, virus replication was increased significantly. The yield of polyhedral inclusion bodies (PIB) was enhanced up to 121%. Synthesis of cell-free nonoccluded virus was increased to 365% when infectivity was assayed by the plaque method. Newly applied electron microscopic quantitation and stereological techniques also revealed a significant increase in virus particles (VP) and in amount and size of PIB as well as number of VP per PIB.

Aluminum↗
PubMed1982

Studies of cervical caps: I. Vaginal lesions associated with use of the Vimule cap.

Prior to investigating the contraceptive efficacy of cervical caps, we undertook a preliminary study to evaluate potential side effects of these devices. Women who had not previously used a cap were randomly assigned to wear either a Vimule or Cavity Rim Cap (CRC) for as long as seven days. The Vimule cap caused lesions of the portio vaginalis ranging from erythematous impressions to abrasions and frank lacerations. There was variation in the degree of trauma depending, in part, on the size of the cap and duration of wear. Disruption of the epithelium occurred in eight of twelve Vimule users, but the lesions were sometimes difficult to see owing to their location. CRCs were worn by 20 women. This device sometimes left a "suction ring" on the cervix but did not disrupt the epithelium. Two of three long-term users of the Vimule cap who were also studied had unusual formations of the vaginal mucosa suggesting a proliferative reaction to chronic irritation. It is recommended that all women using a Vimule Cap be carefully re-examined and counseled about further use of the device according to the findings of the examination.

Adolescent↗
PubMed1982

Anorexic properties of three monoamine oxidase inhibitors.

The anorexic properties of 3 monoamine oxidase (MAO) inhibitors, pargyline, tranylcypromine and nialamide were determined 24 hr after their intra-peritoneal administration. The duration of anorexia occurring after the peripheral administration of the dose of pargyline commonly used in conjunction with 6-hydroxydopamine (6-OHDA) to enhance its dopamine-depleting properties was also determined. Body weight regulation and the control of food and water intake were severely impaired 24 hr after the administration of the three highest doses of pargyline, tranylcypromine and nialamide employed. Impairment in the ability to regulate body weight lasted for as long as 6 days in some animals injected with 50 mg/kg of pargyline. These findings bring to light the problems in interpretation of results from studies which employ MAO inhibitors and 6-OHDA simultaneously to enhance dopamine depleting properties of 6-OHDA.

Animals↗
PubMed1981

Effect of manipulating central catecholamines on puberty and the surge of luteinizing hormone and gonadotropin releasing hormone induced by pregnant mare serum gonadotropin in female rats.

We have investigated the effect of manipulating central catecholamines on the timing of puberty (as assessed by vaginal opening) in female rats and the surge of luteinizing hormone (LH) and gonadotropin releasing hormone (GnRH) induced by pregnant mare serum gonadotropin (PMSG) in immature female rats. Manipulation of the catecholamines was carried out with either 6-hydroxydopamine (6-OHDA) administered with or without either desipramine (DMI) or pargyline, or alpha-methyl-p-tyrosine (alpha-MPT). The neonatal administration of 6-OHDA delayed puberty, an effect which was potentiated by pretreatment with DMI and was associated with a reduction in the rate of body growth. Catecholamine fluorescence in animals aged 60--65 days that had been treated with DMI followed by 6-OHDA was diminished only in the caudatus--putamen; treatment with 6-OHDA alone resulted in diminished fluorescence in the hypothalamus and in the intermediate but not the external layer of the median eminence. The neonatal administration of alpha-MPT had no significant effect on either the growth rate or the timing of puberty. Regular oestrous cycle occurred after puberty in animals treated with either 6-OHDA or alpha-MPT. The PMSG-induced LH surge was significantly enhanced by 6-OHDA (administered i.v.) plus DMI, and reduced by 6-OHDA injected in to the lateral ventricle (v). The inhibitory effect of 6-OHDA (v) was reduced by DMI, but in animals given 6-OHDA (i.v.) after pargyline there was a marked reduction in the height of the LH surge. There was a good correlation between the changes in the concentrations of LH in peripheral plasma and the concentrations of GnRH in pituitary stalk plasma in that the PMSG-induced surge of GnRH was significantly increased by 6-OHDA (i.v.) plus DMI and reduced by 6-OHDA (v). In animals treated with 6-OHDA (i.v. plus DMI catecholamine fluorescence was reduced only in the external layer of the median eminence, while after 6-OHDA (v) plus DMI degeneration was seen in the medial forebrain bundle. These results demonstrate a marked difference between the long-term and acute effects of 6-OHDA on the gonadotropin control system. Neonatal treatment with 6-OHDA plus DMI significantly delays puberty and the rate of body growth, but does not affect cyclical gonadotropin release and has no persistent effect on the hypothalamic catecholaminergic systems. The acute administration of 6-OHDA, depending upon the route of administration and whether it is given after DMI, can either potentiate or inhibit the PMSG-induced surge of GnRH and consequently LH by mechanisms which involve destruction, respectively, of either dopaminergic terminals in the median eminence or catecholaminergic fibres in the dorsal hypothalamus.

Animals↗
PubMed1981

Sickness absence, respiratory impairment and smoking in industry: an australian study.

A retrospective study of sickness absence, respiratory impairment and their relation to smoking habits was conducted among a heterogeneous population of 1867 staff members of 12 Australian organizations. Data on smoking habits were used to divide the sample into current cigarette smokers (n=392), ex-cigarette smokers (n=182) and those who had never smoked (n=714). Results of the health survey by self-administered questionnaire showed that the prevalence of respiratory symptoms was higher in cigarette smokers than in non-smokers both in men and women. Smoking was particularly related to frequency of cough, and sputum production. Wheezing showed a similar, though less marked, trend. The influence of smoking on the pulmonary function value, FEV1/FVC% was assessed in a group of 972 men and 297 women. Results of analysis of variance showed that ventilatory function was significantly impaired among smokers and ex-smokers. The sickness absence records of 826 cigarette smokers, ex-smokers and non-smokers were also compared. Both frequency and duration of sickness absence were greater in cigarette smokers and ex-smokers. Significant differences between these groups were confirmed in total as well as in certified absence. Among males, the average number of days off work was 1.59 times greater in male smokers than in male non-smokers, and 1.36 times greater for female subjects who smoked. The epidemiological implications of such findings await further research. However, the consequences for the individual, industry and the general community are apparent.

Absenteeism↗
PubMed1981

Bacterial growth in ground beef prepared from electrically stimulated and nonstimulated muscles.

Ground beef samples prepared from electrically stimulated and nonstimulated biceps femoris and infraspinatus muscles were inoculated with Lactobacillus sp., Pseudomonas sp., Acinetobacter sp., or a mixture of Lactobacillus spp., Pseudomonas spp., Acinetobacter spp., Moraxella sp., Microbacterium thermosphactum, and Erwinia herbicola. There were no significant differences in growth of various bacteria in ground beef made from electrically stimulated and nonstimulated muscles.

Acinetobacter↗
PubMed1981

Improved replication of Autographa californica nuclear polyhedrosis virus in roller bottles: characterization of the progeny virus.

A reproducible growth curve was established for the propagation of Autographa californica (Speyer) nuclear polyhedrosis virus (ACMNPV) In a continuous insect line from Spodoptera frugiperda (J. E. Smith) during large-volume production. A newly developed method for quantitation of polyhedra inclusion bodies (PIB) by electron microscopy (EM) during the growth cycle was compared to hemocytometer counts. The virus particles (VP) ratio to PFU and VP per PIB were established by EM methods. Optimal yields of PIB and cell-free virus with biological activities were obtained in six consecutive production lots when the growth curve conditions were followed. The DNA of the viruses produced in the 1st and 8th passages in the S. frugiperda cell line was treated with restriction endonucleases and compared with that from the E-2 cloned variant of this virus. Data confirmed that the virus was the ACMNPV and also indicated that there were no detectable changes after 8 passages in insect cell culture.

Animals↗
PubMed1980

Factors influencing the fluorescence spectra of the formaldehyde-induced reaction product of 5-hydroxytryptamine.

Fluorescence excitation and emission spectra of the formaldehyde-induced fluorophore of 5-hydroxytryptamine in a Sephadex model have been examined following exposure to hydrochloric acid or ammonia vapour. Exposure to hydrochloric acid vapour produced excitation spectra with broad maxima centred around 400 nm, whilst exposure to ammonia vapour intensified the maximum normally seen at approximately 450 nm relative to that seen at 400 nm. The emission maximum was generally broad and poorly defined following exposure to hydrochloric acid vapour; exposure to ammonia vapour had little effect on its location. Exposure of the formaldehyde-induced fluorophore in models containing 5-hydroxytryptamine to 300 nm irradiation caused a substantial shift in the position of the emission maximum; a concomitant increase in the fluorescence intensity was also observed. When the fluorescence present in duodenal enterochromaffin cells was examined after similar treatment, a number of differences in the response of the fluorophore were noted.

Ammonia↗
PubMed1979

Differentiation of the formaldehyde-induced fluorescent products of noradrenaline and dopamine by microspectrofluorometry.

The influence of concentration of dopamine and noradrenaline on the spectral characteristics of their formaldehyde-induced fluorophore, together with the influence of duration of reaction with formaldehyde, has been investigated in a model system. No substantial differences between fluorescence spectra of the amine fluorophores were observed. Accordingly, the influence of hydrochloric acid and ammonia vapours on the fluorophores was investigated. A shift to shorter wavelengths in the excitation maximum of each fluorophore was observed after a brief exposure to hydrochloric acid vapour; more prolonged exposure resulted in a pronounced shift back to longer wavelengths in the case of noradrenaline but no substantial change was observed with dopamine. Brief exposure to hydrochloric acid vapour resulted in a substantial increase in the rate of fading of the noradrenaline fluorophore on exposure to exciting radiation. It is suggested that this offers a convenient way of differentiating the amines.

Dopamine↗
PubMed1979

Cell-free varicella-zoster virus in cultured human melanoma cells.

Varicella-zoster virus (VZV) has been isolated and serially propagated in a continuous cell line derived from a human malignant melanoma tumour. Human melanoma cells (HMC) have been further evaluated as a substrate for the production of cell-free virus and compare favourably with human embryo cells. Within 60 h after inoculation with VZV-infected cells, HMC monolayers incubated at 32 degrees C exhibited advanced syncytial cytopathic effect, and the overlying culture medium contained greater than 10(2) p.f.u./ml. The cell pellet from a mechanically dispersed 150 cm2 monolayer yielded 10(5) p.f.u. after sonic disruption, while the medium ('scraping medium') in which the cells had been harvested contained up to one log more infectious virus than was found in the cells from the same monolayer. When infected cells were subjected to Dounce homogenization, most of the infectivity was found in the nuclear fraction. The concentration and purification of cell-free virus were also investigated. Concentration was carried out by three methods: ultracentrifugation, dialysis against hydrophilic compounds and liquid polymer phase separation. The first two procedures caused considerable loss of biological activity, whereas precipitation with 8% polyethylene glycol resulted in a 50-fold increase in titre. Purification of cell-free virus with retention of infectivity was achieved by rate zonal centrifugation in linear potassium tartrate gradients. Infectious virus was also recovered after sedimentation in combination equilibrium-viscosity gradients of potassium tartrate and glycerol, but not after centrifugation to equilibrium in caesium chloride gradients.

Cell Line↗
PubMed1979

Brain amines and peptides--their relevance to psychiatry.

The amine theory of affective disorder and the dopamine and endorphin theories of schizophrenia are controversial but heuristically valuable concepts that have emerged from the psychobiological revolution of the last decade. That revolution stemmed largely from the development of techniques for localizing and assaying neuroregulators and their receptors in the brain under normal, pathological and experimental conditions. The data thus obtained are reviewed here, and the current status of the emergent psychobiological hypotheses assessed.

Amines↗
PubMed1979

Squirrel monkey retrovirus and Herpesvirus saimiri: observation in the same cell following isolation.

Electron microscopic examination of mink lung cells previously cultured with a squirrel monkey (Saimiri sciureus) throat swab suspension revealed the presence of squirrel monkey retrovirus (SMRV) and Herpesvirus saimiri (HVS) coexisting within the same cells in culture. HVS was identified by serum neutralization, and the retrovirus isolate was identified as SMRV by a morphologic examination, microimmunodiffusion analysis, and demonstration of an Mg2+ preference for the RNA-directed DNA polymerase.

Animals↗
PubMed1979

Electron microscopic examination of primate feces for rotaviruses.

Using electron microscopic procedures known to be capable of detecting rotaviruses, feces from both human and nonhuman primates were examined for the presence of these viruses. Fecal samples were taken from man and animals with and without diarrhea. Rotaviruses were not observed in these specimens.

Animals↗