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Biomedical subjects

R Carpenter

Publications and source records attributed to R Carpenter.

At least 163 records · Page 9Linked to original sources
PubMed1986

Transposable elements generate novel spatial patterns of gene expression in Antirrhinum majus.

The pallida gene of A. majus encodes a product required for the synthesis of red flower pigment. We have shown that the unstable pallida(recurrens) mutation is due to the insertion of the Tam3 transposable element near the promoter of the gene. Imprecise excision of Tam3 alters pallida gene expression and generates new spatial patterns or different intensities of flower pigmentation. Distinct spatial patterns may also result from rearrangements induced by Tam3 that alter the relative position of the pallida gene. Changes in Tam3 structure or position result in new unstable phenotypes. These findings suggest that genes may be rendered genetically hypervariable as a consequence of transposable element insertion and excision.

Alleles↗
PubMed1986

Cushing's syndrome resulting from primary pigmented nodular adrenocortical disease.

In a 10-year-old boy with Cushing's syndrome, the dexamethasone suppression test, the metyrapone test, and both basal and corticotropin-releasing factor-stimulated corticotropin levels all indicated a primary adrenal disorder. However, a computed tomographic scan failed to detect an adrenal tumor. At surgery, the adrenal glands were not enlarged but were studded with small pigmented nodules composed of enlarged nonmalignant adrenocortical cells. This unusual abnormality, referred to as primary pigmented nodular adrenocortical disease, is associated with autonomous hypersecretion of cortisol primarily in children and young adults. Our patient was cured by total bilateral adrenalectomy and corticosteroid replacement therapy, the treatment of choice for this condition.

Adolescent↗
PubMed1986

Polymorphonuclear leukocytes, complement, and Trichophyton rubrum.

Trichophyton rubrum can activate complement. In order to assess the role of complement in host defense, fresh human serum was incubated with fungus. Factors were produced which were chemotactic for polymorphonuclear leukocytes (PMNL), but only if complement activation was allowed. This suggests that the chemotactic factor or factors were derived from complement. Incubation of T. rubrum with fresh serum did not prevent fungal growth on subsequent culture, but did inhibit incorporation of radiolabeled N-acetylglucosoamine. The interaction of PMNL and fungi was studied, and the role of complement as a mediator was assessed. PMNL adhered well to fungi provided that the fungal hyphae had been preincubated with fresh human serum to provide complement opsonins. Opsonized and unopsonized fungi both stimulated a respiratory burst in normal PMNL as measured by chemiluminescence, but the burst was generated much faster with opsonized hyphae. Although hyphae with adherent PMNL subsequently proliferated in culture, the incorporation of N-acetylglucosoamine was inhibited 96% when the hyphae were opsonized with fresh serum and then incubated with PMNL. Inhibition was also observed with unopsonized fungi, but to a lesser degree. Varying the ratio of PMNL to hyphae showed that inhibition by PMNL was far more efficient if hyphae were opsonized. In contrast to hyphae, opsonized fungal spores were killed by PMNL so that no growth was observed in subsequent cultures. This killing was not observed if PMNL were omitted or if spores were preincubated with heat-inactivated serum rather than fresh serum. Activation of complement apparently opsonizes the spores so that they can be ingested and killed by viable PMNL. Contents of disrupted PMNL failed to inhibit fungal growth. Complement and PMNL may aid the host in defending itself against infection by dermatophytes.

Acetylglucosamine↗
PubMed1986

Effect of nitrendipine, diltiazem, trifluoperazine and pimozide on serotonin2 (5-HT2) receptor activation in the rat uterus and jugular vein.

The present study explored the calcium source used in serotonin (5-HT)-induced contractions mediated by 5-HT2 receptor activation in the rat uterus and jugular vein in vitro. In the rat uterus, the calcium channel antagonists, nitrendipine and diltiazem, and the neuroleptic agents, trifluoperazine (TFP) and pimozide, antagonized potently and noncompetitively 5-HT-induced contractions. These data are compatible with the contention that 5-HT-induced contractions in uterine smooth muscle require extracellular sources of calcium. In contrast, neither diltiazem nor nitrendipine inhibited the contractile response to 5-HT in the rat jugular vein although 5-HT-induced contractions in the jugular vein required the presence of extracellular calcium. This difference in sensitivity to calcium channel antagonists between the uterus and jugular vein was not related to differences in the receptor occupancy-response curves for 5-HT as these were similar in the rat uterus and jugular vein. Furthermore, in the jugular vein, neither diltiazem nor nitrendipine were markedly effective in blocking contractions produced by potassium chloride, an agent that activates voltage-dependent calcium channels, suggesting that this tissue lacks calcium channels susceptible to blockade by conventional calcium channel antagonists. Although responses to 5-HT in the jugular vein were only affected marginally by calcium channel antagonists, TFP and pimozide produced concentration-dependent rightward parallel shifts of 5-HT-induced contractions in the jugular vein. Furthermore, both TFP and pimozide showed high affinity at 5-HT2 binding sites in rat brain cortical membranes and the apparent dissociation constant at 5-HT2 receptors in the jugular vein was 38 and 31 nM, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1985

Molecular analysis of instability in flower pigmentation of Antirrhinum majus, following isolation of the pallida locus by transposon tagging.

The pal locus of Antirrhinum majus was cloned using the transposable element, Tam 3, as a probe. The pal clone was used to examine, at the molecular level, those aspects of instability previously observed phenotypically and genetically. The effects of temperature and of genetic background on excision of the element at pal are considered, and related quantitatively to the phenotype. We describe the identification of the transcript of the pal locus and show that insertion of Tam 3 blocks the production of a normal pal transcript in developing flower buds.

Journal Article↗
PubMed1985

Rapid changes in the phospholipid composition of gill membranes during thermal acclimation of the rainbow trout, Salmo gairdneri.

The phospholipid composition of gill tissue was determined in rainbow trout (Salmo gairdneri) undergoing thermal acclimation between 5 degrees C and 20 degrees C for a period of up to 28 days. Proportions of phosphatidylethanolamine (PE) and cardiolipin (CL) increased during cold acclimation and decreased during warm acclimation; proportions of phosphatidylcholine (PC) changed in the opposite direction (i.e., decreased during cold acclimation). In contrast, levels of phosphatidylserine, -inositol, and sphingomyelin did not vary significantly. Thermal modulation of headgroup composition occurred rapidly as reflected by changes in the ratio of PC-to-PE, which rose significantly from 2.40 +/- 0.09 to 2.92 +/- 0.09 within 72 h of transfer from 5 to 20 degrees C; adaptation to 5 degrees C was equally rapid. Proportions of PE changed more rapidly than those of PC during cold adaptation, whereas the opposite was true during warm acclimation. Both the time course and the direction of the observed changes in phospholipid composition suggest that such adjustments may contribute to the homeoviscous regulation of membrane properties, particularly during the initial stages of thermal adaptation.

Acclimatization↗
PubMed1985

Membrane attack complex of complement in dermatitis herpetiformis.

The assembly of membrane attack complex (MAC) of complement implies activation of complement to the attachment of C9 and the presence of MAC on tissue suggests a possible pathogenic role for complement in disease since MAC is able to damage membranes. We examined normal skin of five patients with dermatitis herpetiformis for the presence of MAC using a monoclonal antibody (poly C9-MA) that recognizes a neoantigen of C9 that is not present on monomeric C9 but is common to both isolated MAC and to polymerized C9. Granular deposits of polymerized C9 were found at the sites of IgA deposition in the dermal papillae of normal skin from all patients. The pathologic importance of this finding is uncertain.

Antibodies, Monoclonal↗
PubMed1984

Deposition of the membrane attack complex of complement in bullous pemphigoid.

Bullous pemphigoid is associated with deposition of IgG and C3 at the dermal-epidermal junction. In order to see whether complement activation in bullous pemphigoid resulted in deposition of membrane attack complex (MAC) at the basement membrane zone, skin biopsies from patients with bullous pemphigoid were examined using a direct immunofluorescence technique. By employing a monoclonal antibody to a neoantigen of C9, the MAC was demonstrated in linear pattern at the basement membrane zone. These deposits were seen in both involved and uninvolved skin but the amount of MAC was greater in involved skin as judged by intensity of staining. Stippled deposits of MAC were also present in or around epidermal basal cells. The MAC could be generated in vitro by reaction of normal plasma with antibasement membrane antibody bound to sections of monkey esophagus. The IgG antibody activated complement and this complement activation proceeded all the way to the terminal step.

Basement Membrane↗
PubMed1983

Nosocomial surgical infections: incidence and cost in a developing country.

Eight hundred twenty-nine patients were monitored for nosocomial surgical infections from January to December 1980 at the University Hospital of the West Indies. Two hundred twenty-five patients (27%) had 189 postoperative wound infections (POWI) and 295 other nosocomial infections, with an average of 2.1 infections per infected patient. The incidence of POWI was 22.8%, varying from 7.3% in clean to 82.2% in infected wounds. The most common organisms isolated were gram-negative bacilli and Staphylococcus aureus. The most frequent nosocomial infection other than POWI was urinary tract infection (27.8%). A statistically significant number of urinary tract infections and septicemias were associated with the use of medical devices such as indwelling urethral catheters and central venous pressure lines (p less than 0.001). Septicemia was frequently associated with operations on the lower gastrointestinal and hepatobiliary tracts (p less than 0.001). The postoperative stay of an infected patient was prolonged by an average of 18 days. The total excess cost of hospitalization for the infected patients was U.S. $170,000.

Cross Infection↗
PubMed1981

Sonography of fetal urinary tract anomalies.

Experience with 13 cases and a review of 41 cases in English literature indicate that anomalous development of the fetal urinary system can be detected in utero using sonography. Anomalies not compatible with extrauterine life (bilateral renal agenesis, infantile polycystic and bilateral multicystic kidney disease) have distinctive sonographic features that can be detected early enough to allow elective termination. Megacystis, either as a primary finding or secondary to urethral obstruction, can be detected and usually portends a poor fetal outcome. Obstruction at the ureterovesical junction has a distinctive sonographic appearance, but ureteropelvic junction obstruction cannot be differentiated from some cystic renal lesions, particularly when it is unilateral. Even when a precise diagnosis cannot be established in utero, the detection of a fetal renal anomaly may significantly affect obstetric and neonatal management of the benefit of both mother and fetus.

Abnormalities, Multiple↗
PubMed1980

Hypervascularity of the uterine wall during pregnancy: incidence, sonographic appearance, and obstetric implications.

The authors report the incidence (20%) of hypervascularity of the uterine wall (decidual reaction) (1) in 106 pregnant women studied prospectively by ultrasound. An unusual case, which caused problems in diagnosis and management, is reported in detail. The relation between the location and extent of this finding and the location of the placenta is discussed. The authors think that this finding represents dilation of myometrial veins of uncertain etiology, and they conclude that the major implications are that it must be differentiated from pathologic entities that are similar sonographically (1), and that if anterior, it may cause excessive bleeding during invasive procedures.

Adolescent↗
PubMed1980

Fetal ascites not associated with Rh incompatibility: recognition and management with sonography.

Fetal ascites not associated with Rh incompatibility is an uncommon problem that can be detected in utero by sonography. The sonographer should make a systematic search for the cause of ascites in a given case on the basis of well known etiologic possibilities, since this may have a significant effect on the obstetrical management. The use of sonography in the detection, etiologic evaluation, and obstetrical management of nonimmunologic fetal ascites is discussed, and experience with 10 such cases is reported.

Abnormalities, Multiple↗