Biomedical subjects

J L Hall

Publications and source records attributed to J L Hall.

At least 55 records · Page 3Linked to original sources

PubMed1996

Direct complementation of Chlamydomonas mutants with amplified YAC DNA.

We previously described the construction and characterization of a Chlamydomonas genomic library in yeast artificial chromosomes (YACs). Here we describe the isolation and genetic mapping of YACs at the FLA10 locus on the uni chromosome as well as isolation of a YAC spanning the PF14 locus on chromosome VI. Genetic mapping of YAC end clones by RFLP analyses in interspecific crosses reveals that YACs with a physical size of 150 kb commonly span genetic intervals defined by one or two recombination events in crosses of approximately 20 tetrads. This promises to make chromosomal walking in Chlamydomonas a relatively efficient enterprise. We also describe our development of a method for direct complementation of mutant genes by transformation with amplified wildtype YAC DNA. The use of positional cloning using YACs and this direct functional assay for the presence of a gene in a YAC represent powerful molecular genetic tools enabling the cloning of most any Chlamydomonas gene.

Animals↗

PubMed1996

Prevention of respiratory complications after abdominal surgery: a randomised clinical trial.

OBJECTIVE: To evaluate the prevention of respiratory complications after abdominal surgery by a comparison of a global policy of incentive spirometry with a regimen consisting of deep breathing exercises for low risk patients and incentive spirometry plus physiotherapy for high risk patients. DESIGN: Stratified randomised trial. SETTING: General surgical service of an urban teaching hospital. PATIENTS: 456 patients undergoing abdominal surgery. Patients less than 60 years of age with an American Society of Anesthesia classification of 1 were considered to be at low risk. OUTCOME MEASURES: Respiratory complications were defined as clinical features consistent with collapse or consolidation, a temperature above 38 degrees C, plus either confirmatory chest radiology or positive results on sputum microbiology. We also recorded the time that staff devoted to prophylactic respiratory therapy. RESULTS: There was good baseline equivalence between the groups. The incidence of respiratory complications was 15% (35/231) for patients in the incentive spirometry group and 12% (28/225) for patients in the mixed therapy group (P = 0.40; 95% confidence interval -3.6% to 9.0%). It required similar amounts of staff time to provide incentive spirometry and deep breathing exercises for low risk patients. The inclusion of physiotherapy for high risk patients, however, resulted in the utilisation of an extra 30 minutes of staff time per patient. CONCLUSIONS: When the use of resources is taken into account, the most efficient regimen of prophylaxis against respiratory complications after abdominal surgery is deep breathing exercises for low risk patients and incentive spirometry for high risk patients.

Abdomen↗

PubMed1996

Capsaicin-induced biphasic oxygen uptake in rat muscle: antagonism by capsazepine and ruthenium red provides further evidence for peripheral vanilloid receptor subtypes (VN1/VN2).

Previous studies with the vanilloid spice principle capsaicin have demonstrated a biphasic VO2 response, with vasoconstriction, in the perfused rat hindlimb that has led to suggestions of vanilloid receptor subtypes (VN1/VN2) in this preparation (1). In the present study, the known competitive vanilloid antagonist capsazepine inhibited the above capsaicin-mediated effects in a manner that was indicative of binding at specific vanilloid recognition sites. Low concentrations of capsazepine selectively inhibited the increased VO2 produced by the putative VN1 receptor at submicromolar concentrations of capsaicin, while the inhibition of VO2 produced by high concentrations of capsaicin (putative VN2) was enhanced. These observations, showing different susceptibilities to blockade by capsazepine, further support the presence of two vanilloid receptor subtypes in the rat hindlimb. Schild plots of the data yielded variable slopes that approach unity at greater responses to capsaicin (mean KB = 8.44 +/- 2.08 microM and 7.28 +/- 0.78 microM for VO2 and perfusion pressure curves, respectively). Low concentrations of the capsaicin antagonist ruthenium red selectively blocked the putative VN2 receptor-mediated effects produced by high concentrations of capsaicin. The noncompetitive nature of this inhibitor suggests an operation through separate receptor-coupled ion channel complexes at high and low concentrations of the vanilloid. Tetrodotoxin failed to attenuate any changes produced by capsaicin, suggesting that the mechanism of action of capsaicin in the rat hindlimb may differ from other tissues.

Animals↗

PubMed1996

Hyperglycemia results in an increase in myocardial interstitial glucose and glucose uptake during ischemia.

The purpose of this investigation was to assess the effects of hyperglycemia, in the absence of changes in plasma insulin and arterial free fatty acid (FFA) levels, on interstitial glucose levels and glucose uptake across the left ventricular wall during ischemia in domestic swine. Insulin secretion was suppressed with a continuous infusion of somatostatin. Arterial FFA levels remained stable due to the suppression of insulin. Microdialysis probes were used to estimate changes in interstitial glucose and lactate, and were placed in the subepicardium and the subendocardium of the left anterior descending ([LAD] ischemic) coronary artery perfusion bed and in the midmyocardium of the circumflex ([CFX] nonischemic) perfusion bed. The LAD coronary artery was cannulated and perfused with blood from the femoral artery through an extracorporal perfusion circuit. Ischemia was induced in the LAD perfusion bed by reducing the flow of the LAD perfusion pump by 60% for 50 minutes, and was followed by 30 minutes of reperfusion. Twenty minutes into the ischemic period, seven animals were given a bolus injection of 50% glucose (200 mg/kg) followed by a glucose infusion (10 mg/kg/min), resulting in an increase in arterial glucose levels from 5 to 13 mmol/L in the hyperglycemic group. Hyperglycemia resulted in a marked increase in dialysate glucose during ischemia and a greater than twofold increase in glucose extraction and uptake. Dialysate glucose correlated with plasma glucose in all three perfusion beds. In conclusion, hyperglycemia, in the absence of an increase in insulin and a decrease in arterial FFA, resulted in a doubling of glucose extraction, delivery, and uptake, which corresponded to the twofold elevation in interstitial glucose during ischemia.

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

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

Double-blind, randomized trial of cessation of smoking after audiotape suggestion during anaesthesia.

We studied the use of intraoperative tape suggestion to improve the rate of cessation of smoking in 363 smokers who wanted to stop smoking. They were allocated randomly to hear a taped message encouraging them to stop smoking or to a blank tape, played during general anaesthesia. Overall 56 patients (15.4%, 95% confidence interval (CI) 11.7-19.1%) had claimed to have stopped smoking at 2 months and 29 patients (8.0%, 95% CI 5.9-10.1%) were confirmed to have stopped smoking at 6 months. There was no significant difference between the groups at either 2 or 6 months (risk ratios 1.06 and 1.09, respectively, P = 0.78). A preoperative:postoperative ratio of a visual analogue scale measuring the patient's motivation to stop smoking was not significantly different (control group 1.13 vs message group 1.10, P = 0.55). This study does not support the hypothesis that intraoperative tape suggestion can change smoking behaviour.

Adolescent↗

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

Impaired pyruvate oxidation but normal glucose uptake in diabetic pig heart during dobutamine-induced work.

We tested the hypothesis that diabetes impairs myocardial glucose uptake and pyruvate oxidation under normal conditions and during a dobutamine-induced increase in work. We also tested the hypothesis that an increase in work would result in a decrease in the levels of malonyl CoA, a potent inhibitor of carnitine palmitoyltransferase I (CPT I). Streptozotocin-diabetic micropigs were compared with a nondiabetic control group (n = 8 per group). Triglyceride emulsion, glucose, and somatostatin were infused into the nondiabetic group to create an acute diabetic-like state. In accord with our hypothesis, malonyl CoA decreased significantly with dobutamine in both groups, providing a possible mechanism for increased fatty acid oxidation through relieved inhibition on CPT I. In the absence of dobutamine, glucose uptake and tracer-measured lactate uptake were decreased by 57 and 80%, respectively, in the diabetic group. Dobutamine infusion resulted in similar increases in cardiac contractility, oxygen consumption, and glucose uptake in both groups despite reductions of 50-65% in GLUT-4 and GLUT-1 protein in the diabetic group. Diabetic animals possessed a defect in myocardial pyruvate oxidation, as reflected in increased lactate production, and depressed lactate uptake and pyruvate dehydrogenase activity under control and dobutamine conditions. In conclusion, the major derangement in carbohydrate metabolism in diabetic myocardium was not in glycolysis but, rather, in pyruvate oxidation.

Acetyl-CoA Carboxylase↗

PubMed1996

The kinesin-homologous protein encoded by the Chlamydomonas FLA10 gene is associated with basal bodies and centrioles.

We previously reported that the FLA10 locus on the uni linkage group of Chlamydomonas encodes a kinesin homologous protein, KHP1. The fla10 phenotype, which is a temperature-sensitive defect for flagellar assembly and maintenance, is rescued by transformation with the wild-type KHP1 gene. In the present study we identify the molecular defect associated with the fla10 mutation and examine the subcellular localization of KHP1 throughout the cell cycle. The mutation in the fla10-1 allele consists of a C to A transversion, which alters amino acid 329 in the motor domain of KHP1. This residue and the sequence of the carboxy-terminal third of the motor domain in which it is located are highly conserved throughout eukaryotic evolution in a subfamily of kinesin-related proteins from mouse (KIF3), sea urchin (KRP85/95), Xenopus (XKLP3), and Drosophila (KLP68D). These data suggest a conserved function for this family of proteins. Immunofluorescence studies reveal that: (1) in interphase cells KHP1 is associated with basal bodies and with the proximal portion of the flagella; (2) in cells undergoing flagellar regeneration KHP1 occurs in punctate structures that extend to the tip of the developing axoneme; and (3) in dividing cells KHP1 remains associated with centrioles throughout mitosis and localizes to the mitotic spindle. KHP1 is the first kinesin homologous protein to be found in association with basal bodies and centrioles throughout the cell cycle. These observations provide evidence for a direct role of basal bodies in the process of flagellar development, which we propose is based on KHP1 acting as a transporter of flagellar components from the basal bodies out to the distal site of assembly. The localization of KHP1 in mitosis suggests that this protein may play an analogous role in the centriole-based assembly of the mitotic spindle.

Alleles↗

PubMed1996

The quality of life of patients on a waiting list for transurethral resection of the prostate.

We evaluated the quality of life of 50 patients with benign prostatic hypertrophy on a waiting list for transurethral resection of the prostate. The patients had a median age of 68 years (range: 48-84 years) and had been on the waiting list for a median of eight months (range: 2-36 months). Patients were assessed using the Benign Prostatic Hypertrophy Health-Related Quality of Life Survey Questionnaire. All patients had disagreeable urinary symptoms that interfered with their normal activities, for example, 92% of patients were troubled by disturbed sleep. The patients also had worries about the possibility of prostatic cancer (40%) and a perceived deterioration in sexual performance during the preceding year (56%). Eleven of the 14 patients who were re-evaluated one year after a transurethral resection of the prostate were completely free of any bothersome urinary symptoms.

Aged↗

PubMed1996

ASA status and age predict adverse events after abdominal surgery.

The objective of this study was to evaluate the ability of age and the American Society of Anesthesiologists (ASA) score to act as clinical indicators and predict clinical adversity after abdominal surgery. We evaluated 2570 patients who underwent abdominal surgery. The data were collected in a prospective manner with an unbiased measurement of the baseline risk and endpoint criteria. Age > 60 years and/or an ASA score > 2 identified over 80% of the patients who had a prolonged stay in hospital, developed intraperitoneal sepsis, were admitted to the ICU or died. This effect was additive which implies a useful degree of independence between the two risk factors. Age and the ASA score are useful indicators of clinical adversity and resource utilization after abdominal surgery. Hence, they can be used to benchmark the outcome of abdominal surgery between institutions.

Abdomen↗

PubMed1996

Increased cardiac fatty acid uptake with dobutamine infusion in swine is accompanied by a decrease in malonyl CoA levels.

OBJECTIVE: Malonyl CoA is an important regulator of fatty acid oxidation in the heart secondary to its ability to inhibit carnitine palmitoyltransferase 1 (CPT 1). Malonyl CoA is produced from acetyl CoA in a reaction catalyzed by acetyl CoA carboxylase (ACC). In this study we determined if alterations in malonyl CoA regulation of fatty acid metabolism are involved in the increase in energy transduction seen following an increase in cardiac work. METHODS: Anesthetized, open-chest, domestic swine were subjected to a 30 min control period followed by a 30 min treatment period with either dobutamine (15 micrograms.kg-1. min-1 i.v.) (n = 6) or saline (n = 6). RESULTS: Heart rate, left ventricular peak dp/dt, and MVO2, were significantly increased in the dobutamine group compared to the saline group during the treatment period. Free fatty acid and glucose uptake were increased 210 and 248%, respectively, in the dobutamine group during the treatment period. Malonyl CoA content was decreased by 55% (from 0.40 +/- 0.05 to 0.18 +/- 0.12 nmol/g wet wt; P < 0.05) with dobutamine treatment, but was not affected by saline treatment. ACC activity was not significantly different between groups (0.31 +/- 0.02 vs. 0.30 +/- 0.04 nmol. min-1. mg protein-1, respectively). The activity of AMP-dependent protein kinase (AMPK), which phosphorylates and inactivates ACC, was also not significantly different in the dobutamine hearts compared to the saline hearts (322 +/- 26 vs. 338 +/- 39 pmol. min-1. mg protein-1, respectively). CONCLUSION: The increased cardiac work following dobutamine infusion is accompanied by a decrease in malonyl CoA levels and an increase in fatty acid uptake. However, the decrease in malonyl CoA cannot be explained by a decrease in ACC activity.

Animals↗

PubMed1995

The uni chromosome of Chlamydomonas: histone genes and nucleosome structure.

The uni linkage group (ULG) of Chlamydomonas reinhardtii contains many genes involved in the basal body-flagellar system. Recent evidence suggests that the corresponding uni chromosome is located in close proximity to the basal body complex. In the course of studies into its molecular organization, we have found a cluster of four histone genes on the ULG. The genes are arranged as divergently-transcribed pairs: H3-H4 and H2B-H2A. Genomic sequencing reveals that these genes lack introns and contain characteristic 3' palindromes similar to those of animals. The predicted amino acid sequences are highly conserved across species, with greatest similarities to the histone genes of Volvox. Southern analysis shows that each histone gene is present in 15-20 copies in Chlamydomonas and suggests a dispersed genomic organization. Northern analysis of mitotically-synchronized cells shows that, like the replication-dependent histones of higher eukaryotes, Chlamydomonas histone genes are expressed during S-phase. Using a gene-specific probe on Northern blots, we provide evidence that the ULG H4 gene is regulated in the same manner as other Chlamydomonas histone genes. Finally, micrococcal nuclease protection experiments show that the uni chromosome itself associates with histone proteins and displays a conventional nucleosomal banding pattern.

Amino Acid Sequence↗

PubMed1995

Basal body-associated DNA: in situ studies in Chlamydomonas reinhardtii.

We have explored the localization of the uni chromosome (LG XIX) of Chlamydomonas reinhardtii using the technique of in situ hybridization. Using standardized methods of cell fixation together with large chromosome-specific probes we have studied the position of uni DNA sequences in metaphase and interphase cells. We find that in dividing cells uni probes identify a condensed metaphase chromosome that shows no specialized orientation. In interphase cells uni hybridization signals occur on the anterior edge of the nucleus at a position where basal bodies are normally associated with the nuclear envelope. These data reveal an underlying spatial organization of uni chromosomal DNA within the interphase nucleus that may be significant in terms of the fact that this chromosome encodes numerous functions affecting basal body and flagellar assembly.

Animals↗