Search PubMed⌕ Search

Biomedical subjects

M May

Publications and source records attributed to M May.

At least 109 records · Page 6Linked to original sources
PubMed1995

Dependence of flight behavior and heat production on air temperature in the green darner dragonfly Anax junius (Odonata: Aeshnidae)

The large, endothermic dragonfly Anax junius regulates the temperatures of its thorax (Tth) and head (Th) during flight. At high ambient temperature (Ta) it is able to dispose of excess heat from the thorax by increasing hemolymph circulation to the abdomen, but recent evidence suggests that heat loss to the abdomen is largely passive at Ta<30 &deg;C. Nevertheless, these insects continue to regulate Tth and Th at least down to 20 &deg;C and probably at much lower values of Ta. As Ta declines, A. junius glide less, probably fly faster when feeding, and increase their wingbeat frequency when patrolling. Presumably as a result of these behavioral changes, heat production, and thus inferred flight metabolic rate, is inversely proportional to Ta. This is the first demonstration based on field data that an insect regulates body temperature while flying by altering heat production.

Journal Article↗
PubMed1994

Aarskog-Scott syndrome: confirmation of linkage to the pericentromeric region of the X chromosome.

Aarskog-Scott syndrome was tentatively mapped to Xq13 on the basis of an X:8 translocation by Bawle et al. [Am J Med Genet 17:595-602, 1984]. A review of the cytogenetics and the use of molecular markers in that family have resulted in revision of the breakpoints of the translocation to Xp 11.2 and 8q11.21 [Glover et al., Hum Mol Genet 2:1717-1718, 1993]. Two families, including one of the two initial families with Aarskog-Scott syndrome [Scott, BD:OAS VII (6): 240-246, 1971], have participated in our study to evaluate the localization of the gene for Aarskog-Scott syndrome to the pericentromeric region of the X chromosome. Using a series of DNA probes, we have been able to confirm linkage to the X chromosome, with multipoint analysis indicating the most likely localization of the gene to be on the proximal short arm.

Abnormalities, Multiple↗
PubMed1994

The E6/E7 promoter of extrachromosomal HPV16 DNA in cervical cancers escapes from cellular repression by mutation of target sequences for YY1.

Human papillomavirus type 16 (HPV16) induces squamous intraepithelial lesions of the cervical mucosa which may develop into invasive cancer. The expression of viral oncogenes in advanced neoplasias appears increased relative to the proliferating cell layers of low grade lesions raising questions about molecular mechanisms of deregulation of transcription. In a lymph node metastasis of a cervical cancer, we observed full-length HPV16 plasmids and molecules with a small deletion, which was mapped to the long control region (LCR). Both wild type and shortened LCR were amplified by PCR, cloned into the promoter test plasmid pBLCAT6 and sequenced to identify a 107 bp deletion from position 7794 to 7901 in the short LCR. CAT expression in cervical cancer-derived HT3, SiHa and CaSki cells appeared 5- to 6-fold increased under the control of the short LCR. This could be traced back to elevated levels of mRNA initiated at the viral oncogene promoter. A slight further increase in CAT expression was noted in the presence of the HPV16 E2 protein which is probably due to the deletion of one E2 binding site and consequent relief from E2 repression. Computer-assisted sequence analysis and band-shift experiments with purified YY1 protein and wild type or mutated oligonucleotides identified four binding sites for this cellular transcriptional repressor within the promoter-proximal segment of the HPV16 LCR, three of which were removed by the deletion. A LCR fragment comprising these YY1 binding sites was cloned in front of the heterologous thymidine kinase gene promoter and suppressed CAT expression 3- to 4-fold.(ABSTRACT TRUNCATED AT 250 WORDS)

Base Sequence↗
PubMed1994

Transcriptional silencer of the human papillomavirus type 8 late promoter interacts alternatively with the viral trans activator E2 or with a cellular factor.

The noncoding region of the highly oncogenic, epidermodysplasia verruciformis-associated human papillomavirus type 8 contains a negative regulatory element (NRE). Quantitative RNase protection analysis confirmed that the NRE sequence acts as a silencer of transcription. A 38-bp sequence upstream of late promoter P7535 down-regulated expression from the homologous P7535 promoter, as well as the heterologous tk gene promoter, independently of its orientation relative to the test promoters. It also reduced gene expression when cloned downstream of the transcription units. Transient expression assays with keratinocytes and fibroblasts of epidermodysplasia verruciformis patients and controls demonstrated that the NRE activity is not cell specific. Gel retardation tests suggested that NRE specifically interacts with only one nuclear factor. Mutational analysis identified three NRE mutants which no longer formed a detectable DNA-protein complex but still repressed transcription, indicating that protein-DNA interaction is not relevant for the silencer function. The NRE contains a binding site of viral trans activator protein E2. It was shown that expression of E2 overrides the inhibitory effect of the NRE sequences. Binding of E2 and that of the cellular factor were mutually exclusive. The bifunctional nature of NRE acting as a silencer and a target site for viral trans activator E2 offers an interesting opportunity to regulate the switch from early to late transcription in the human papillomavirus life cycle.

Base Sequence↗
PubMed1994

Complications of endoscopic sinus surgery: analysis of 2108 patients--incidence and prevention.

The incidence of complications of endoscopic sinus surgery (ESS) in a combined experience with 2108 total patients is compared to complications in 11 other series of patients (2583 total) who underwent ESS and 6 series of patients (2110 total) who underwent traditional endonasal sinus surgery. The incidence of major perioperative complications was 0.85%, with cerebrospinal fluid (CSF) leak being the most common. The most common minor complications of ESS were those related to orbital penetration and middle turbinate adhesions; minor complications occurred in 6.9% of the 2108 patients. There were no statistically significant differences in the overall incidences of major complications between this series and the other two groups. Recommendations are made for the prevention of complications during ESS.

Bronchial Spasm↗
PubMed1994

Identification, localization and functional analysis of imidazoline and alpha adrenergic receptors in canine prostate.

In nonsurgical management of benign prostatic hyperplasia, drugs which interfere with prostate contraction mediated through the alpha-1 adrenergic receptor are used. Clonidine acts at alpha adrenergic and I1-imidazoline receptors. In the present study, we found the Kd for [3H]clonidine binding to I1 sites in canine prostate to be 4 +/- 1 nM; the Bmax was 18 +/- 2 fmol/mg of protein. Inhibition of binding by imidazolines and by brain extracts containing putative endogenous ligand confirmed the identity of these sites as I1-imidazoline. Autoradiographic studies showed localization of both I1 and alpha-2 sites to the glandular epithelium. We sought to determine whether in vivo activation of the I1-imidazoline sites by clonidine mediates its contractile action in canine prostate. Dose-response curves were generated for para-aminoclonidine in the presence of vehicle alone, yohimbine (alpha-2 antagonist), idazoxan (alpha-2/I1/I2 antagonist) and prazosin (alpha-1 antagonist). Prazosin was the most effective antagonist. Yohimbine was less effective and did not effectively discriminate between para-aminoclonidine and phenylephrine, an alpha-1-selective agonist. Idazoxan antagonized para-aminoclonidine, but by not more than 50% at any dose. These results suggest that clonidine is active primarily at alpha-1 receptors on prostate smooth muscle in vivo. Thus the function of the I1 and alpha-2 receptors in the prostate remains to be determined; however, they may be involved in epithelial cell function.

Animals↗
PubMed1994

Preauricular cyst associated with congenital cholesteatoma: an unusual cause of facial palsy.

An unusual case is reported in which a preauricular cyst associated with a congenital cholesteatoma caused facial nerve paralysis in a 40-year-old woman. The patient underwent three exploratory temporal bone operations to locate a source of facial nerve compression, but the cause of the palsy was not found until resection of a preauricular cyst revealed an epithelial tract that was traced through the external auditory canal and across the tegmen tympani to the site of the cholesteatoma.

Adult↗
PubMed1993

Platelet-derived growth factor AB heterodimer interchain interactions influence secretion as well as receptor binding and activation.

Platelet-derived growth factor (PDGF) is a disulfide-linked dimer comprised of two related polypeptide chains. To investigate the effects of an inactivating lesion introduced into one chain of the nascent PDGF dimer, approaches were developed to optimize synthesis, assembly, secretion, and purification of heterodimers between normal PDGF A and wild-type or mutant PDGF B. PDGF AB heterodimers were released into culture fluids less efficiently than PDGF AA, but to a greater degree than the cell-associated PDGF BB. These results suggest that interactions between two chains influence PDGF secretion. Analysis of heterodimers between PDGF A and disabled PDGF B mutants on cells that express either alpha or beta PDGFRs demonstrated that the impaired biologic activity of the mutant PDGF B chain was ameliorated with respect to binding and triggering of alpha PDGFRs. In cells that expressed both receptor types, heterodimers of mutant PDGF B and wild-type PDGF A gained substantially in their ability to recruit and trigger alpha, but not beta, PDGFRs. Partial rescue of impaired PDGF B mutant chain function by dimer formation with a wild-type PDGF A chain implies that interchain interactions markedly affect PDGFR binding and activation.

3T3 Cells↗
PubMed1993

Temporalis muscle for facial reanimation. A 13-year experience with 224 procedures.

A procedure for temporalis muscle transposition was used to reanimate the paralyzed face in 219 patients. In most cases, facial paralysis had followed an operation to remove an acoustic tumor. Analysis of the results showed this procedure to be highly successful and the method of choice, alone in cases of long-standing facial paralysis or to augment the effects of facial nerve grafting or hypoglossal-facial nerve anastomosis, in reanimating the mouth. It was successful in restoring a smile to 80% of the 219 patients and provided overall improvement in mouth function in 96%. Complications occurred in 21% of patients, with the most common being infection (12% of patients). Since one of us began to use the procedure to reanimate the eye and mouth, results of temporalis muscle transposition have been improved by the following: (1) using the procedure to reanimate the mouth only; (2) performing revision surgery, most often tightening the corner of the mouth (25% of patients), as indicated; (3) transposing only the midsection of the muscle; (4) implanting a prefabricated Silastic prosthesis to fill the muscle defect; (5) when indicated, lengthening the muscle with polytef (Gore-Tex+); and (6) placing the muscle in a tunnel lateral to the superficial musculoaponeurotic system to avoid injuring the underlying facial nerve should some spontaneous recovery of facial nerve function be possible.

Adolescent↗
PubMed1993

Histological and bacteriological findings in long-term ileocystoplasty and colocystoplasty in the rat.

The long-term effects of bladder reconstruction using bowel were studied in rats. Bladder surgery consisted of cystotomy and closure, ileo- or colocystoplasty, or placement of a reverse serosal (Thal) patch of ileum. At least one-third of all groups received prophylactic cefaclor, postoperatively. Monthly urine cultures were obtained, and survivors were sacrificed at 1 year. Antimicrobial therapy markedly reduced the incidence of chronic colonization after cystoplasty. However, the majority of rats in the Thal patch group remained colonized because of acquired vesicoileal fistulae. Vesical stones were often present in this group and were also seen in 6 of 43 (14%) and 3 of 33 (9%) in the ileocystoplasty and colocystoplasty groups, respectively. Transitional cell papillomas and/or hyperplasia was seen at 20 of 42 (48%) uroileal and 20 of 31 (64%) urocolonic anastomoses (p = .15). Hyperplastic lesions could not be correlated with bacteriuria. Focal nonpapillary transitional cell carcinoma was seen once in the colocystoplasty group, and low grade papillary transitional cell tumors were noted once in each of the cystostomy and ileocystoplasty groups and twice in Thal patch rats with ileovesical fistulae. These findings suggest that the rat uroenteric anastomosis is susceptible to proliferative change which is rarely malignant in nature and occurs in the presence or absence of bacteriuria.

Animals↗