PubMed Health⌕ Search

Biomedical subjects

C Guyer

Publications and source records attributed to C Guyer.

5 recordsLinked to original sources
PubMed2000

Seasonal changes in sex and adrenal steroid hormones of gopher tortoises (Gopherus polyphemus).

We sampled a population of gopher tortoises (Gopherus polyphemus) from May to October 1997 to determine seasonal cycles of steroid hormones (testosterone, T; 17beta-estradiol, E; and progesterone, P) and related them to observations of mating behavior. In males, plasma T levels peaked in July and August and remained elevated through October. This coincides with the reported time of peak mating and spermatogenesis, indicating that males display an associated pattern of reproduction. In females, E levels were high in September and October. Plasma T levels in females were elevated in May, decreased to basal levels in June and July, and rose again in August and September. Elevated E and T levels correspond to the reported time of peak vitellogenic activity, indicating that females also display an associated cycle. Plasma P in females remained basal throughout the active season, suggesting that ovulation occurs in late winter. We also determined levels of corticosterone (B) to assess the influence of capture stress on tortoises and correlated B levels with tortoise activity patterns and sex steroid levels. We found no seasonal variation in levels of B in males or females. Plasma B levels were not correlated with levels of T or E, but were positively correlated with female P levels. Further, we found no relationship between plasma B levels in males and mean distance moved, mean number of burrows used, or mean home range size. However, there was a significant negative correlation between plasma B levels and male body size. In females, there was no relationship between B levels and mean distance moved, but B levels were significantly negatively correlated with the number of burrows females occupied. Lastly, there was no relationship between levels of B and the number of minutes required to obtain blood from an animal. However, B levels increased with the length of time that a tortoise spent in a trap, suggesting that trapped tortoises do exhibit capture stress.

Adrenal Cortex Hormones↗
PubMed2000

An audit of conservative surgery for endometriosis in a district general hospital 1995-1998.

As conservative surgery for endometriosis is a relatively new introduction to our hospital we felt it would be of value to audit our results and compare these with results from published series. We sent postal questionnaires to 104 patients who had undergone surgery over the past 3 years to assess their response to treatment. We combined this with an additional questionnaire to patients who had a Laparoscopic uterine nerve ablation (LUNA) procedure. We received replies from 81% of the patients with 81% having symptom improvement following their operation. Eighty-seven per cent of patients who had LUNA returned the questionnaire with 64% having some symptom improvement following surgery. On the basis of our results we will continue to offer conservative surgery for endometriosis as the best primary treatment but have some reservations about the addition of LUNA in patients with endometriosis.

Journal Article↗
PubMed1997

Brain cytochrome oxidase subunit complementary DNAs: isolation, subcloning, sequencing, light and electron microscopic in situ hybridization of transcripts, and regulation by neuronal activity.

The goal of the present study was to isolate, for the first time, cytochrome oxidase subunit genes from murine brain complementary DNA library and to characterize the expression of these genes from mitochondrial and nuclear sources at both light and electron microscopic levels. Brain subunit III (mitochondrial) shared 100% identity with that of murine L cells. Subunit VIa (nuclear) was known to have tissue-specific isoforms in other species: the ubiquitous liver isoform and the heart/muscle isoform. Our brain subunit VIa shared 93% homology with that of the rat liver and 100% identity with the recently reported murine liver isoform, which is only 62% identical to that of the rat heart isoform. In situ hybridization with riboprobes revealed messenger RNA labelling that was similar, though not identical, to that of cytochrome oxidase histochemistry. Monocular enucleation in adult mice induced a significant down-regulation of both subunit messages in the contralateral lateral geniculate nucleus. However, the decrease in subunit III messenger RNAs surpassed that of subunit VIa at all time periods examined, suggesting that mitochondrial gene expression is more tightly regulated by neuronal activity than that of nuclear ones. At the electron microscopic level, subunit III messenger RNA was localized to the mitochondrial compartment in both cell bodies and processes, while that of nuclear-encoded subunit VIa was present exclusively in the extramitochondrial compartment of somata and not of dendrites or axons. Surprisingly, the message was primarily associated with the rough endoplasmic reticulum, suggesting a novel pathway for its synthesis and trafficking. Our results indicate that the unique properties of neurons impose special requirements for subunits of a single mitochondrial enzyme with dual genomic origins. At sites of high energy demands (such as postsynaptic dendrites and some axon terminals), mitochondrial-encoded cytochrome oxidase subunits can be locally transcribed and translated, and they provide the framework for the subsequent importation and incorporation of nuclear-encoded subunits, which are strictly synthesized in the cell bodies. Dynamic local energy needs are met when subunits from the two genomic sources are assembled to form functional holoenzymes.

Animals↗