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Biomedical subjects

P A Thorpe

Publications and source records attributed to P A Thorpe.

16 recordsLinked to original sources
PubMed2000

Microbes in tree swallow semen.

A frequently hypothesized but poorly studied cost of multiple mating in birds is that exposure to pathogenic sexually transmitted microbes (STM's) can lower reproductive success. Conversely, female birds may benefit from high frequencies of copulation and multiple copulation partners if they receive cloacal inoculations of beneficial STM's that can either protect them against future encounters with pathogens and/or serve as therapy against present infection. We examined the semen of 30 male tree swallows (Tachycineta bicolor) in 1998 to determine the presence and prevalence of potential pathogenic and beneficial STM's. Semen was collected directly from males after applying gentle pressure to the cloaca and we used standard microbiological techniques to identify microbes. We found that 19 of 30 samples contained one or more types of microbes. In these 19 positive samples, we isolated both pathogenic and beneficial microbes from 11, only pathogenic microbes from seven, and only beneficial microbes from one. This variation among males suggests that females would benefit from considering a particular male's potential as a donor of either pathogenic or beneficial STM's as a criterion for mate choice. There were few significant differences between males with pathogen-infected semen and those without pathogens in their semen in measures of size, morphology, and ectoparasite score and feather damage. Likewise, there were few significant differences between males with beneficial Lactobacilli spp. in their semen and those without Lactobacilli spp. in their semen in measures of size, morphology, and ectoparasite score and feather damage. We were unable to determine if there was a relationship between microbe presence and prevalence on reproductive performance.

Animals↗
PubMed1998

Primary extramedullary plasmacytoma of the parotid gland: a case report and review of the literature.

Solitary extramedullary plasmacytomas are uncommon malignant neoplasms with a great predilection for the upper respiratory tract. Extramedullary plasmacytoma involving the parotid gland is an extremely rare condition. This report describes the case of a primary extramedullary plasmacytoma arising in the right parotid gland of a 63-year-old man. A review of the literature reveals that this disease has generally a good prognosis. provided that multiple myeloma has been excluded. The treatment of choice should be surgical excision followed by radiotherapy, although from this study there is insufficient evidence to suggest that this is more effective than surgery alone. All patients must have regular long-term follow-up to monitor for recurrence or dissemination, in which event chemotherapy may be considered in addition to the other treatment modalities.

Diagnosis, Differential↗
PubMed1996

Molecular organization of the alcohol dehydrogenase loci of Drosophila grimshawi and Drosophila hawaiiensis.

To determine sequences involved in conserved and species-specific aspects of alcohol dehydrogenase (Adh) gene expression in Hawaiian Drosophila, a 3644-base pair (bp) region containing the D. grimshawi gene and the homologous 3335-bp region containing the D. hawaiiensis Adh gene were sequenced. These genes have the two-promoter and exon-intron structure seen for many Drosophila Adh genes. Analysis of putative and known regulatory sequences of the D. grimshawi and D. hawaiiensis genes in comparison to those of D. affinidisjuncta (the only other Hawaiian species for which the promoter organization is known) highlighted elements likely to be involved in conserved aspects of Adh gene expression as well as sequences that may account for species-specific differences in tissue-specific expression. Sequence comparisons, in the context of regulatory roles previously assigned to particular gene fragments, indicated that multiple insertions and deletions in the promoter regions are responsible for differences in tissue-specific regulation displayed by these genes.

Alcohol Dehydrogenase↗
PubMed1996

The antimicrobial properties of chile peppers (Capsicum species) and their uses in Mayan medicine.

A survey of the Mayan pharmacopoeia revealed that tissues of Capsicum species (Solanaceae) are included in a number of herbal remedies for a variety of ailments of probable microbial origin. Using a filter disk assay, plain and heated aqueous extracts from fresh Capsicum annuum, Capsicum baccatum, Capsicum chinese, Capsicum frutescens, and Capsicum pubescens varieties were tested for their antimicrobial effects with fifteen bacterial species and one yeast species. Two pungent compounds found in Capsicum species (capsaicin and dihydrocapsaicin) were also tested for their anti-microbial effects. The plain and heated extracts were found to exhibit varying degrees of inhibition against Bacillus cereus, Bacillus subtilis, Clostridium sporogenes, Clostridium tetani, and Streptococcus pyogenes.

Anti-Bacterial Agents↗
PubMed1995

Follicular Hodgkin's disease.

We describe four cases of Hodgkin's disease that presented histologically as purely follicular lesions. The Reed-Sternberg (RS) cells were of classic and lacunar type and had the phenotype of usual Hodgkin's disease (CD30 and CD15 positive) but also expressed B-cell antigens (CD20 and CD79a). In each case the follicles consisted principally of mantle-zone B cells, which enclosed the RS cells; the follicle centres were atrophic, usually eccentrically placed, and did not contain RS cells. Fifteen cases of typical nodular sclerosing Hodgkin's disease were reviewed in parallel. B-cell antigen expression by RS cells was found in 10 cases (66%), and RS cells were present in follicular mantles in 10 cases. These findings suggest that some RS cells may be derived from B cells in the follicular mantle.

Adult↗
PubMed1993

Evolution of regulatory genes and patterns: relationships to evolutionary rates and to metabolic functions.

In an effort to understand the forces shaping evolution of regulatory genes and patterns, we have compared data on interspecific differences in enzyme expression patterns among the rapidly evolving Hawaiian picture-winged Drosophila to similar data on the more conservative virilis species group. Divergence of regulatory patterns is significantly more common in the former group, but cause and effect are difficult to discern. Random fixation of regulatory variants in small populations and/or during speciation may be somewhat more likely than divergence driven by selection. Within the picture-winged group, we also have compared enzymes that fulfill different metabolic roles. There are highly significant differences between individual enzymes, but no obvious correlations to functional categories.

Animals↗
PubMed1984

Absence of direct repeats flanking transposons resulting from intramolecular transposition.

Tn2660 is an ampicillin-resistance-conferring transposon with a high degree of homology for the transposon Tn3. The nucleotide sequences flanking the termini of Tn2660 have been determined on plasmids inferred to have resulted from both inter- and intramolecular transposition of Tn2660. In all cases, transposition of Tn2660, as of Tn3, creates 5-bp flanking direct repeats, except following intramolecular transposition resulting from trans ligation. In this case, in R6K replicons, the nucleotide sequence between the two Tn2660 elements is stably inverted from the normal orientation, and 5-bp direct repeats do not flank each transposon, but instead flank opposite ends of the two transposon copies.

Base Sequence↗
PubMed1976

The accessory optic system of the ferret.

The accessory optic system of the ferret has been studied both by silver degeneration staining and by autoradiography after intraocular 3H leucine injections. There is no anterior accessory optic tract but a posterior tract containing only crossed fibres leaves the brachium of the superior colliculus and ends in the two nuclei, the medial and lateral terminal nuclei, lying either side of the cerebral peduncle. Both suprachiasmatic nuclei receive retinal fibres visible only on autoradiographs; most fibres end in the contralateral nucleus. No other area in the hypothalamus appears to receive retinal fibres demonstrated by these methods.

Animals↗
PubMed1976

The effect of lesions of the accessory optic tract terminal nuclei on the gonadal response to light in ferrets.

Electrolytic lesions were made in the lateral (LTN), medial (MTN) or in both terminal nuclei of the accessory optic tract in female ferrets. Either the ipsilateral or contralateral eye was removed. Complete destruction of both nuclei, as assessed by both histological and autoradiographic criteria, did not prevent the acceleration of estrus by artificial long days (L:D, 14:10) in any animal. Although the ferret has no anterior (inferior) accessory tract, lesions were also made in the medial forebrain bundle (MFB) area in ipsilaterally and contralaterally enucleated animals. Estrus still occurred in response to artificial long days in these animals. The experiments suggest that the accessory optic system in the ferret does not transmit information to the pineal regulating the annual breeding season.

Animals↗
PubMed1976

Studies on the duration of the breeding season and photorefractoriness in female ferrets pinealectomized or treated with melatonin.

Oestrous ferrets became anoestrous on exposure to short photoperiods (8 h light: 16 h darkness, 8L:16D) at the summer solstice, and this effect was prevented by pinealectomy. Removal of the pineal alone did not alter the duration of oestrus in animals kept in natural daylight. Melatonin (1 mg, thrice weekly) given to oestrous ferrets kept in daylight also terminated oestrus prematurely. Animals made photorefractory by prolonged exposure to long photoperiods (14L:10D) became photosensitive again if either given melatonin or transferred to short photoperiods (8L:16D) for 7 weeks. These findings show that the pineal gland of the oestrous ferret is involved in the termination of oestrus when the animal is exposed to experimental short photoperiods. This is in addition to its role in inducing oestrus when anoestrous animals are exposed to long days, an effect shown previously. Thus, neither phase of the annual breeding cycle is altered by experimental lighting regimes in pinealectomized animals. Furthermore, some of the effects of short days (but not of long days), including that on photosensitivity, can be replicated by melatonin in the ferret.

Anestrus↗