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Biomedical subjects

J C Hall

Publications and source records attributed to J C Hall.

At least 127 records · Page 7Linked to original sources
PubMed1996

Staining in the brain of Pachymorpha sexguttata mediated by an antibody against a Drosophila clock-gene product: labeling of cells with possible importance for the beetle's circadian rhythms.

Central nervous system ganglia within the head of the beetle Pachymorpha sexguttata were labeled using an antibody that recognizes an evolutionarily conserved region of the period (per) gene product of Drosophila melanogaster. per and the protein it encodes (PER) are believed to play a central role in the generation of endogenous circadian rhythms in flies; therefore anti-PER-mediated immunoreactivity may help to uncover cellular components of the circadian clock system in that insect and in others. In the beetle, application of this antibody led to the staining of a distinct set of neurons located in the optic lobes and the central brain, plus small numbers of putative glial cells in the optic lobes. Neuronal perikarya (including their nuclei in a few cases), the axons, and terminal regions of the neurons were stained. The network formed by these labeled cells and processes are candidates for the neuronal basis of the beetle's circadian clock system: the pacemaker region situated next to the medulla neuropil, its connection to the apparent site of Zeitgeber input, and putative efferent pathways projecting to control centers of various effector systems. Anti-PER-mediated labeling and that resulting from application to beetle specimens of an antiserum against pigment-dispersing hormone (PDH) were compared; in the Drosophila brain all "PDH cells" express the per gene as well. In the beetle, however, the set of "PER cells" and PDH ones is at least in part nonoverlapping. The hypothesis that neurons stained by application of anti-PER participate in the control of the beetle's circadian rhythms is discussed in the context of previous electrophysiological and immunohistochemical studies. Also considered are analogies to, and differences from, labeling of the PER protein in fruit flies and PER-like immunoreactivity in other animals.

Animals↗
PubMed1996

Green fluorescent protein and its derivatives as versatile markers for gene expression in living Drosophila melanogaster, plant and mammalian cells.

We have investigated the utility of the green fluorescent protein (GFP) as a marker for gene expression in living adult Drosophila melanogaster (Dm) and cultured plant and mammalian cells. Using Dm, we generated transgenic flies bearing a glass-responsive gfp fusion gene to test the utility of GFP as a spatial reporter. In the adult living fly, GFP is clearly visible in the ocelli and the eye. We have optimized the use of filters for distinguishing the GFP signal from abundant autofluorescence in living Dm. In addition, we have used GFP to identify photoreceptor cells in pupal eye cultures that have been fixed and stained according to standard histological procedures. GFP was also detected in individual living plant cells following transient transfection of soybean suspension cultures, demonstrating that GFP is an effective transformation marker in plant cells. Similarly, transient transfection of mammalian cells with a modified form of GFP, S65T, allowed detection of single living cells expressing the reporter. This modified form of GFP gave a robust signal that was resistant to photobleaching. We then used a CellScan system exhaustive photon reassignment (EPR) deconvolution algorithm to generate high-resolution three-dimensional images of GFP fluorescence in the living cell.

Animals↗
PubMed1996

Methodologic standards in surgical trials.

BACKGROUND: Concerns have been raised that flaws in the design and analysis of trials will hinder the interpretation of their relevance to clinical practice. The objective of this study was to review the nature and methodologic standards of surgical trails published in 10 prestigious journals between January 1988 and December 1994. METHODS: We evaluated the demography and methodologic standards of 364 trials. Each article was independently scrutinized by two assessors with documentation of the interassessor variation. RESULTS: Less than 50% of the trials made comment about an unbiased assessment of outcome, gave an adequate description of the randomization technique, or provided a prospective estimate of the sample size. Economic factors were declared in 6.5% of the trials. Only 2% of the trials attempted to measure the effect of an intervention on the quality of life patients. CONCLUSIONS: Readers should be cautious when interpreting the results of surgical trials.

Clinical Trials as Topic↗
PubMed1996

Antibiotic prophylaxis for patients undergoing transurethral resection of the prostate.

OBJECTIVES: To evaluate the prevention of urinary tract infections (UTIs) after transurethral resection of the prostate (TURP) in a prospective randomized study using a quinolone antibiotic (fleroxacin) to compare the efficacy of: (1) a single oral dose, (2) a single intravenous (IV) dose, and (3) an extended regimen consisting of an initial IV dose followed by oral therapy until removal of the urinary catheter, but for less than 6 days. METHODS: We excluded from study patients who received antimicrobial agents within 48 hours of surgery. Single-dose prophylaxis consisted of 400 mg of fleroxacin given either orally or intravenously. The extended regimen consisted of an initial 400 mg IV dose followed by 400 mg oral each day (patients older than 75 years, or with a creatinine clearance less than 40 mL/min, received 200 mg/day). UTI was defined as clinical evidence of infection plus the presence of more than 10 white blood cells (WBC)/mm3 in any urine specimen plus the presence of more than 10(4) cfu/mL in midstream urine specimens or more than 10(2) cfu/mL in catheter specimens. RESULTS: Prior to TURP, 30% (25/84) of the patients had a urethral catheter in situ and 12% (3/25) of these patients had bacteriuria. Only 1 patient developed a UTI and that was 22 days after a TURP (intergroup comparisons, Fisher's exact test greater than 0.05). There were no instances of urosepsis. CONCLUSIONS: A single oral dose of a fluoroquinolone agent provided optimum prophylaxis for patients undergoing TURP.

Administration, Oral↗
PubMed1996

Evaluation of a wound scoring method for patients undergoing cardiac surgery.

The main endpoint of studies evaluating antimicrobial prophylaxis in surgical patients is wound morbidity. This should consist of more than the solitary declaration of the rate of wound infection. In this study, a modified version of ASEPSIS (a wound scoring system) has been prospectively evaluated in 1000 patients undergoing cardiac surgery. Twenty-one patients (2.1%) had an infected sternal wound. The components of ASEPSIS most significantly associated with a sternal wound infection were: the presence of a purulent exudate, a postoperative stay > 14 days, the identification of pathogenic organisms, and the use of antibiotics (P < 0.0001). Although ASEPSIS is a useful mechanism for conveying information about wounds, it does ignore bleeding into wounds and the extent that troublesome wounds need to be dressed after surgery.

Aged↗
PubMed1996

Novel features of drosophila period Transcription revealed by real-time luciferase reporting.

The rapid turnover of luciferase and the sensitive, non-invasive nature of its assay make this reporter gene uniquely situated for temporal gene expression studies. To determine the in vivo regulatory pattern of the Drosophila clock gene period (per), we generated transgenic strains carrying a luciferase cDNA fused to the promoter region of the per gene. This has allowed us to monitor circadian rhythms of bioluminescence from pacemaker cells within the head for several days in individual living adults. These high time-resolution experiments permitted neuronal per transcription and opens the door to vastly simplified experiments in general chronobiology and studies of temporally regulated transcription in a wide range of experimental systems.

Animals↗
PubMed1996

The timSL mutant of the Drosophila rhythm gene timeless manifests allele-specific interactions with period gene mutants.

To identify new components of the Drosophila circadian clock, we screened chemically mutagenized flies for suppressors or enhancers of the long periods characteristic of the period (per) mutant allele perL. We isolated a novel mutant that maps to the rhythm gene timeless (tim). This novel allele, timSL, alters the temporal pattern of perL protein nuclear localization and restores temperature compensation to perL flies. timSL more generally manifests specific interactions with different per alleles. The identification of this first period-altering tim allele provides further evidence that TIM is a major component of the clock, and the allele-specific interactions with PER provide evidence that the PER/TIM heterodimer is a unit of circadian function. Although timSL fails to restore PER-L/TIM temperature insensitivity in yeast, it alters the TIM phosphorylation pattern during the late night. The effects on phosphorylation suggest that timSL functions as a partial bypass suppressor of perL and provide evidence that the TIM phosphorylation program contributes to the circadian timekeeping mechanism.

Alleles↗
PubMed1996

Characterization of high-affinity protein D binding sites on the surface of rat epididymal spermatozoa.

125I-labeled protein D was shown to bind to whole rat epididymal sperm in a time-dependent, saturable, and reversible manner. Scatchard analysis indicates that there are 3.4 x 10(5) binding sites/sperm cell with a binding efficiency (Kd) of 2.3 x 10(-10) M. Binding of protein D to sperm reaches equilibrium by 95 min. and is reversible by 30 min. Specific binding of protein D to sperm pre-treated with a dilute trypsin solution is reduced significantly when compared with controls. Our findings establish that protein D-specific binding proteins displaying characteristics of a true receptor are present on the surface of rat epididymal sperm.

Animals↗
PubMed1996

A case-control study of postoperative pulmonary complications after laparoscopic and open cholecystectomy.

Postoperative pulmonary complications (PPC) are common after upper abdominal surgery. The objective of this case-control study was to compare the incidence of PPC after laparoscopic cholecystectomy (LC) and open cholecystectomy (OC) within a tertiary care center. Patients were accrued from two sequential clinical trials that evaluated the role of incentive spirometry in the prevention of PPC after abdominal surgery. Included for study were patients with gallstones undergoing elective surgery who had an American Society of Anesthesiologists (ASA) classification < 3. All patients included in the study were encouraged to use an incentive spirometer at least 10 times each hour while awake. Patients with chronic bronchitis were excluded from study, as were patients who received other forms of physical therapy. OC was performed through either a transverse or an oblique incision. There was an equitable dispersion of putative risk factors for PPC between the groups at baseline. PPC were defined as clinical features consistent with collapse/consolidation, an otherwise unexplained temperature above 38 degrees C, plus either confirmatory chest radiology or positive sputum microbiology. The incidence of PPC was 2.7% (1/37) after LC and 17.2% (10/58) after OC (p < 0.05). It is concluded that PPC are less common after laparoscopic cholecystectomy than after open cholecystectomy.

Abdomen↗
PubMed1996

Bioassaying putative RNA-binding motifs in a protein encoded by a gene that influences courtship and visually mediated behavior in Drosophila: in vitro mutagenesis of nonA.

The no-on-transient-A (nonA) gene of Drosophila melanogaster influences vision, courtship song, and viability. The nonA-encoded polypeptide is inferred to bind single-stranded nucleic acids. Although sequence-analysis of NONA implies that it belongs to a special interspecific family of this protein type, it does contain two classical RNA recognition motifs (RRM). Their behavioral significance was assayed by generating transgenic strains that were singly or multiply mutated within the relatively N-terminal motif (RRM1) or within RRM2. Neither class of mutation affected NONA binding to polytene chromosomes. The former mutations led to extremely low viability, accompanied by diminished adult longevities that were much worse than for a nonA-null mutant, implying that faulty interpolypeptide interactions might accompany the effects of the amino-acid substitutions within RRM1. All in vitro-mutated types caused optomotor blindness and an absence of transient spikes in the electroretinogram. Courtship analysis discriminated between the effects of the mutations: the RRM2-mutated type generated song pulses and trains that tended to be mildly mutant. These phenotypic abnormalities reinforce the notion that nonA's ubiquitous expression has its most important consequences in the optic lobes, the thoracic ganglia, or both, depending in part on the nonA allele.

Animals↗
PubMed1996

Courtship anomalies caused by doublesex mutations in Drosophila melanogaster.

The role played by the sex-determining gene doublesex (dsx) and its influence on Drosophila courtship were examined. Against a background of subnormal male-like behavior that is reported to be an attribute of haplo-X flies homozygous for the original dsx mutation, and given that a sex-specific muscle is unaffected by genetic variation at this locus, analyses of several reproductive behaviors and control for genetic background effects indicated that XY dsx mutants are impaired in their willingness to court females. When they did court, certain behavioral actions were normal, including components of courtship song. However, these mutants never produced courtship humming sounds. Mature XY dsx flies elicited anomalously high levels of courtship; that this occurs merely because of a delay in imaginal development was experimentally discounted. The current analysis reconciled two ostensibly conflicting reports involving the courtship-stimulating qualities of this mutant type. Such experiments also uncovered a new behavioral anomaly: dsx mutations caused chromosomal males to court other males at abnormally high levels. These results are discussed from the perspective of doublesex's influence on internal tissues of adult Drosophila involved in the triggering and neural control of male- and female-like elements of courtship, reproductive pheromone production, or a combination of such factors.

Analysis of Variance↗
PubMed1996

Quantification and localization of N-acetyl-beta-D-hexosaminidase in the adult rat testis and epididymis.

An affinity-purified polyclonal antibody against N-acetyl-beta-D-hexosaminidase (EC 3.2.1.52) from adult rat epididymis was used to develop an ELISA, to localize tissue antigen by immunocytochemistry, and to identify isoforms of the enzyme by Western blot analysis. While peak activity level was measured in the corpus region of the epididymis, the quantity of soluble enzyme protein was highest in the caput region. Luminal caput sperm were intensely immunopositive, whereas epithelial cells were weakly stained. The enzyme was localized to epithelial and sperm cells of the corpus and caudal regions. In the testis, the enzyme was restricted primarily to lymphatic spaces. Testicular cells were unreactive, but spermatids were weakly stained. Western blot analysis revealed three prominent immune-reactive protein variants of approximately 63 kDa, approximately 55 kDa, and approximately 31 kDa. The approximately 31-kDa immune-reactive protein variant was reduced by > 84% in the caput epididymis compared to the cauda and corpus regions. These data suggest that regional differences in N-acetyl-beta-D-hexosaminidase activity in the rat epididymis may be due to differences in cellular synthesis and/or posttranslational processing of the enzyme.

Amino Acid Sequence↗
PubMed1996

The effect of minimum luminal nutrition on bacterial translocation and atrophy of the jejunum during parenteral nutrition.

In situations of catabolic stress, the gut becomes atrophic and may have diminished barrier function as evidenced by an increase in bacterial translocation. The aim of this study was to examine the effect of minimum luminal nutrition during parenteral nutrition on the extent of jejunal atrophy and rate of bacterial translocation. Central venous lines were inserted into 30 rats before they underwent randomization to receive nutritional support with: (a) conventional parenteral nutrition; (b) conventional parenteral nutrition with 3 g/day of rat food (i.e., minimum luminal nutrition); or (c) rat food ad libitum. The rats were assessed after 10 days for nutritional status, extent of jejunal atrophy, caecal flora, as well as the extent of bacterial translocation to the mesenteric lymph nodes, liver and spleen. Rats in the rat food ad libitum group lost the smallest amount of weight and had the least amount of jejunal atrophy, yet had a similar rate of bacterial translocation as the parenterally nourished groups. When compared with the conventional parenteral nutrition group, the minimum luminal nutrition group had better preservation of the weight of the small bowel and its isolated mucosa (P < 0.01), but had a similar rate of bacterial translocation. Minimum luminal nutrition reduced the extent of atrophy of the gut but did not affect the incidence of bacterial translocation. It is inferred that there is no direct relationship between the extent of mucosal atrophy and incidence of bacterial translocation.

Animal Feed↗
PubMed1996

Respiratory insufficiency after abdominal surgery.

The objective of this study was to define the relationship between respiratory insufficiency (RI) and various putative risk factors for patients undergoing abdominal surgery. A review of 1332 adults undergoing abdominal surgery was undertaken. Information was collected in a unbiased, prospective and uniform manner with regard to baseline characteristics, perioperative events and adverse outcomes after surgery. Respiratory Insufficiency was defined as either: a PO2 < 60 mm Hg, the performance of a tracheotomy, or endotracheal intubation for more than 24 h. The incidence of RI was 3% (40/1332). A logistic regression analysis only identified an American Society of Anesthesia (ASA) classification > 2 (P < 0.001) and the presence of chronic bronchitis (P (P < 0.05) as significant risk factors. In addition, 33% (8/24) of the patients who developed postoperative intraperitoneal sepsis and 30% (14/47) of the patients who underwent a reoperation developed RI. It was concluded that patients with a significant systemic disease (ASA > 2), as well as patients with chronic bronchitis, should be the recipients of intense efforts to prevent pulmonary complications after abdominal surgery.

Aged↗
PubMed1996

White blood cell counts in patients undergoing abdominal surgery.

BACKGROUND: The role of pre-operative white blood cell counts (WBCC) in patients with an acute abdomen is contentious. METHODS: This study documents the association between pre-operative WBCC and the extent of intraperitoneal inflammation at the time of surgery in a heterogeneous group of 1166 patients undergoing abdominal surgery. RESULTS: WBCC failed to adequately discriminate between groups of patients with varying degrees of intraperitoneal inflammation. For example, only 31% (37/118) of the patients with either free pus or an abscess within the peritoneal cavity had a WBCC > 15.0 x 10(9)/L. CONCLUSIONS: There is a need to replace the WBCC with more powerful predictors of inflammation within the peritoneal cavity.

Abdomen↗
PubMed1996

Role of GABA in shaping frequency tuning and creating FM sweep selectivity in the inferior colliculus.

1. We examined the role of gamma-aminobutyric acid (GABA)-mediated inhibition in shaping excitatory tuning curves and creating selectivity for frequency-modulated (FM) sweeps in 29 neurons in the central nucleus of the inferior colliculus (ICC) of the pallid bat, with the use of single-unit recording coupled with the iontophoretic application of bicuculline methiodide (BIC), an antagonist of GABAA receptors. 2. BIC increased response magnitude 2 to 6 times over pretreatment levels in > 80% of neurons tested, and converted > 50% of nonmonotonic intensity-rate functions to monotonic or plateaued functions, demonstrating that GABAergic input normally limited response magnitude and inhibited responses at higher intensities. BIC typically had little effect on response thresholds, except in more specialized neurons that normally responded poorly to tones. In these cases, BIC disinhibited the neurons' responses to tones and lowered excitatory thresholds as much as 25 dB. 3. We examined the effects of BIC application on both excitatory and inhibitory tuning curves (measured with simultaneous 2-tone inhibition) to determine whether inhibitory curves were GABA mediated and whether removal of this inhibition was accompanied by an expansion of the excitatory curve. BIC had variable effects on the width of excitatory curves. In most cases, excitatory curves were at least slightly broadened, and expanded into regions previously occupied by inhibitory curves. In most cases, excitatory curves were at least slightly broadened, and expanded into regions previously occupied by inhibitory curves. However, in a few cases, inhibitory curves could be eliminated without an expansion of the excitatory curve. The greatest effect was seen in neurons with closed excitatory tuning curves; blocking GABAergic input caused the curves to open, allowing the neurons to respond at higher intensities. 4. Approximately 50% of the neurons in the ICC tuned to the spectrum of the bat's downward FM sweeping biosonar pulse respond preferentially to downward FM sweeps and not to upward sweeps, tones, or noise. In all neurons tested, BIC at least partially destroyed selectivity for sweep direction. This destruction could occur, however, without a loss of response exclusivity; in some cases, the neurons still did not respond to tones or noise. These results suggest that response selectivity for a species-specific signal is created by GABAergic input to ICC neurons. These results are used to suggest a mechanism that creates selectivity for FM sweep direction.

Acoustic Stimulation↗
PubMed1996

Temporally manipulated rescue of visual and courtship abnormalities caused by a nonA mutation in Drosophila.

The no-on-transient-A gene was identified by independently isolated mutations causing visual-response abnormalities or courtship song defects. The nonA(diss) mutant is abnormal for all of these phenotypes. The pleiotropic effects of this dissonance allele dovetail with the widespread tissue expression of the nonA products. This gene, which encodes a putative RNA-binding protein, is expressed at essentially all stages of the life cycle. To determine whether the behavioral and physiological abnormalities exhibited by nonA mutant adults have a developmental etiology or are the result of an impaired mature nervous (or perhaps neuro-muscular) system, a conditional form of this gene was constructed. Animals from the resulting hsp-nonA (cDNA) transgenic strain were subjected to heat-shock regimes such that the gene's coding sequences were activated during development only, solely in the imaginal stage, or both. Surprisingly, expression during any of these time periods effected rescue of the visual-response and the courtship-song defects.

Animals↗