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Biomedical subjects

M D Williams

Publications and source records attributed to M D Williams.

At least 19 recordsLinked to original sources
PubMed1998

Analysis of the transcriptional activity of the 5'-flanking region of the rat catalase gene in transiently transfected cells and in transgenic mice.

Transiently transfected cell lines and transgenic mice were used to study the transcriptional activity of the 5'-flanking region of the catalase gene. Fragments of the 5'-flanking region of the rat catalase gene ranging in length from 3,421 base pairs (bp) to 69 bp were fused to the chloramphenicol acetyltransferase (CAT) reporter gene, and the transcriptional activity of the reporter gene was measured following transient transfection in three cell lines: a human hepatoma cell line (HepG2), a porcine kidney epithelial cell line (LLCPK1), and a human glioma cell line (U-138 MG). The 3,421-bp fragment of the 5'-flanking region resulted in a high level of expression of the reporter gene in all three cell lines. Shorter fragments of the 5'-flanking region resulted in a decrease in the level of CAT reporter expression that varied among the three cell lines, implying the presence of tissue-specific regulatory sites. To study the tissue-specific regulation of the catalase promoter, transgenic mice containing the 3,421-bp 5'-flanking sequence attached to the CAT reporter gene were produced, and CAT expression was measured in various tissues of three independent transgenic lines. CAT activity was consistently high in muscle tissue (heart, skeletal muscle, and diaphragm) and low in most other tissues studied, particularly in liver and kidney. In contrast, the endogenous expression of catalase is low in muscle and high in liver and kidney; thus, the tissue-specific expression of the reporter gene driven by the 3,421-bp fragment of the 5'-flanking region of the catalase gene was not similar to the expression of the endogenous catalase gene.

Animals↗
PubMed1997

The Neurobehavioral Cognitive Status Examination: accuracy of the "screen-metric" approach in a clinical sample.

This study assessed the accuracy of the "screen" versus "metric" portions of eight subtests of the Neurobehavioral Cognitive Status Examination (NCSE). As part of a routine hospital assessment, 95 male patients were administered both portions of the instrument regardless of outcome on the screen. Results indicate that the screen items of some of the NCSE subtests produced a relatively high false negative rate, where the screen was passed, but the metric was failed. It is recommended that all items of the subtests be administered to more fully assess each domain and, therefore, reduce the probability of overlooking significant deficits.

Aged↗
PubMed1997

Isolation and structure of the human cancer cell growth inhibitory cyclodepsipeptide dolastatin 16.

An investigation of the sea hare Dolabella auricularia from Papua New Guinea has led to discovery of the new cyclodepsipeptide dolastatin 16 (3) containing two new amino acid units designated dolamethylleuine (Dml) and dolaphenvaline (Dpv). The structural elucidation was achieved by means of high-field (500 MHz) NMR and tandem MS/MS mass spectral interpretations and allowed the assignment of cyclo-(Pro-Dpv-Pro-Dml-O-Lac-Pro-O-Hiv-MeVal). The new depsipeptide exhibited strong inhibition of growth against a variety of human cancer cell lines.

Animals↗
PubMed1997

Caring for patients with HIV disease: the experience of a generic hospice.

This study describes the experience of a generic hospice admitting people with advanced HIV disease over a 4-year period. Data were collected retrospectively for all patients with HIV disease admitted. The aim of the study was to review the number of referrals, the reason for referral, subsequent symptom control and multidisciplinary team involvement together with the outcome for these patients. Twenty-six patients were admitted for the first time. Two patients were female, 24 were male; median age was 36 years (range 25-58 years). Hospitals referred more patients than general practitioners (18 (70%) and 5 (20%) respectively), but most were from non-HIV specialist areas within hospitals (11 (42%)). The commonest reason for referral was locality, particularly in terms of ease of access. The most prevalent symptoms on admission were weakness, immobility and weight loss (77%, 73% and 62% respectively). These were not improved during admission. There was significant improvement in the control of other symptoms including pain, gastrointestinal disturbance, confusion and dyspnoea. Use of the full multidisciplinary team was high. Median length of stay was 19 days (range 1-77 days). Seventeen patients (65%) died on their first admission. This study confirms the high prevalence of symptomatology among patients with HIV disease. Many generic hospices can offer skilled multidisciplinary symptom control and psychosocial care, complementing other HIV specialist services. It is important that patients with HIV disease and specialist health care professionals working in the HIV field are made aware of what generic hospices are able to offer so that patients can make informed choices about their care.

Adult↗
PubMed1997

Enteral nutrition after bone marrow transplantation.

Nutritional insult after bone marrow transplantation (BMT) is complex and its nutritional management challenging. Enteral nutrition is cheaper and easier to provide than parenteral nutrition, but its tolerance and effectiveness in reversing nutritional depletion after BMT is poorly defined. Nutritional status, wellbeing, and nutritional biochemistry were prospectively assessed in 21 children (mean age 7.5 years; 14 boys) who received nasogastric feeding after BMT (mean duration 17 days) and in eight children (mean age 8 years, four boys) who refused enteral nutrition and who received dietetic advice only. Enteral nutrition was stopped prematurely in eight patients. Greater changes in weight and mid upper arm circumference were observed in the enteral nutrition group, while positive correlations were found between the duration of feeds and increase in weight and in mid upper arm circumference. Vomiting and diarrhoea had a similar incidence in the two groups, while fever and positive blood cultures occurred more frequently in the dietetic advice group. Diarrhoea occurring during enteral nutrition was not associated with fat malabsorption, while carbohydrate malabsorption was associated with rotavirus infection only. Enteral feeding did not, however, affect bone marrow recovery, hospital stay, general wellbeing, or serum albumin concentrations. Hypomagnesaemia, hypophosphataemia, zinc and selenium deficiency were common in both groups. In conclusion, enteral nutrition, when tolerated, is effective in limiting nutritional insult after BMT. With existing regimens nutritional biochemistry should be closely monitored in order to provide supplements when required.

Body Weight↗
PubMed1997

Prediction of trauma mortality using a neural network.

A neural network is a computerized construct consisting of input neurons (which process input data) connected to hidden neurons (to mathematically manipulate values they receive from all the input neurons) connected to output neurons (to output a prediction). Neural networks are created and trained via multiple iterations over data with known results. In 1993, 897 trauma patients were either declared dead in the emergency room (ER; 76 cases), admitted to the intensive care unit (427 cases, 36 deaths), or taken directly to the operating room (394 cases, 29 deaths). Using only data available from the ER, a neural network was created, and 628 cases were randomly selected for training. After 268 iterations, the network was trained to correctly predict death or survival in all 628 cases. This trained network was then tested on the other 269 cases without our providing the death or survival result. Its overall accuracy was 91 per cent (244 of 269 cases). It was able to predict correctly 60 per cent (12 of 20 cases) of the postoperative or post-intensive care unit admission deaths and 90 per cent (26 of 29 cases) of the deaths in the ER. Computerized neural networks can accurately predict a trauma patient's fate based on inital ER presentation. The theory and use of neural networks in predicting clinical outcome will be presented.

Age Factors↗
PubMed1997

Cholecystectomy following the introduction of laparoscopy: more, but for the same indication.

To assess whether indications for cholecystectomy might have changed after the introduction of laparoscopic cholecystectomy (LC), the data from patients undergoing cholecystectomy at the University of South Alabama Medical Center during 1988 (before LC) and 1993 (after the introduction of LC) were retrospectively analyzed and compared. In 1993, the number of patients undergoing cholecystectomy for gallstone-related disease was 18 per cent higher than in 1988 (87 vs 103, 1.4 per cent of all noncardiac operations vs 2.7 per cent, Chi square; P = 0.003). There was no difference in the mean Preoperative Severity Index, a quantitative evaluation of symptom complex, preoperative laboratory evaluation, and radiological findings. Besides obesity, there were also no differences between the groups in associated comorbidities that might affect the decision to proceed with operation. Furthermore, pathologic findings, including the distribution of patients with gallstone pancreatitis, symptomatic cholelithiasis, chronic cholecystitis, and acute cholecystitis, were similar in both groups. The indications for cholecystectomy did not broaden after the introduction of LC, but rather, more patients with similar indications are undergoing cholecystectomy now, as compared with the pre-laparoscopic era.

Alabama↗
PubMed1997

Absence of inhibitors in previously untreated patients with severe haemophilia A after exposure to a single intermediate purity factor VIII product.

Use of high purity and recombinant factor VIII (FVIII) concentrates has been thought to be associated with an increased incidence of FVIII inhibitors in patients with severe haemophilia A. Comparison with comparable historical control groups has suggested that the true incidence of inhibitors in patients with severe haemophilia A was approximately 20-25%, similar to the incidence seen with new high purity and recombinant FVIII products. We have conducted a study of inhibitor development in a cohort of 37 boys with severe haemophilia A (VIII:C <2 u/dl) exposed only to a single FVIII concentrate (BPL 8Y) with no previous blood or blood product exposure. This factor VIII concentrate is an intermediate purity product with a specific activity of approximately 2 IU/mg protein and contains well preserved von Willebrand factor multimers. It is manufactured by conventional fractionation technologies and terminally dry heat treated at 80 degrees C for 72 h.

Antibodies↗
PubMed1996

Assessment of in vivo attachment/phagocytosis by alveolar macrophages.

Alveolar macrophages (AMs) are recognized as an important first line of cellular host defense within the lung. Although mechanisms underlying AM response to microorganisms or particulates are well characterized in vitro, experimental approaches to the study of AMs in vivo are limited. To circumvent these limitations, a new assay was developed using fluorescently labelled liposomes or Pneumocystis carinii (PC) organisms which were administered intratracheally into mechanically ventilated rats. After 30 min, the lungs were lavaged and the percentage of administered liposomes or PC bound to AMs was determined by quantifying fluorescence. Factors known to enhance attachment/phagocytosis by AMs in vitro were assayed to determine their effect in vivo. For example, vitronectin (VN)-coated liposomes increased attachment from 25.2 +/- 2.4% to 47.2 +/- 3.0% (p < 0.001), while addition of VN increased the binding of PC to AMs from 16.5 +/- 1.7% to 24.5 +/- 2.2% (p < 0.05). Confocal laser microscopy of cells obtained by lavage provided morphologic evidence of attachment/phagocytosis by AMs. This model will permit the quantitative assessment of the interaction of fluorescently labelled liposomes or microorganisms with AMs in the lower respiratory tract of living animals.

Animals↗
PubMed1996

The bryostatins inhibit growth of B16/F10 melanoma cells in vitro through a protein kinase C-independent mechanism: dissociation of activities using 26-epi-bryostatin 1.

Bryostatin 1 is a potential cancer chemotherapeutic agent in Phase II clinical trials, with positive responses observed for malignant melanoma, among other tumors. The bryostatins are known to be potent ligands for protein kinase C (PKC), functioning as partial antagonists. In the present study, we explore the mechanism by which the bryostatins inhibit growth to B16/F10 mouse melanoma cells in vitro. Three experimental approaches suggest that the growth inhibition is independent of PKC. First, we characterized in detail the translocation and down-regulation of the PKC isozymes alpha, delta, and epsilon in response to phorbol ester and bryostatin 1 in these cells. Although the dose-response curves obtained for the translocation-activation of PKC isozymes showed good correlation with the growth-enhancing activity of phorbol 12-myristate 13-acetate, for no PKC isozyme was there a good correlation with the growth-inhibitory activity of bryostatin 1. Second, inhibition PKC, inhibited the growth of the B16/F10 melanoma cell lines with potency similar to that of bryostatin 1. We confirmed here that 26-epi-bryostatin 1 showed 60-fold reduced affinity for PKC and 30-60-fold reduced potency to translocate and downregulate PKC isozymes compared with bryostatin 1. We presumed that the principal toxicity of bryostatin 1 reflects its interaction with PKC, and we would thus predict that epi-bryostatin 1 would be less toxic. Indeed, we found at least 10-fold reduced toxicity of 26-epi-bryostatin 1 in C57BL/6 mice compared with bryostatin 1. We conclude that the growth inhibition of the bryostatins, at least in this system, does not result from interaction with PKC. As exemplified by 26-epi-bryostatin 1, this insight permits the design of analogues with comparable growth inhibition to bryostatin 1 but with reduced toxicity.

Animals↗
PubMed1996

Expression of genes coding for antioxidant enzymes and heat shock proteins is altered in primary cultures of rat hepatocytes.

The expression of genes for heat shock proteins in the HSP70 family and genes for antioxidant enzymes was studied in rat hepatocytes cultured in either L-15 or Williams E media on a collagen matrix for up to 48 hours. The mRNA transcripts for the heat shock proteins hsp70, hsc70, and grp78 were induced dramatically when hepatocytes were cultured in L-15, and to a lesser extent when cultured in Williams E. The increase in hsp70 and hsc70 mRNA levels in the cultured hepatocytes was correlated with an increase in the nuclear transcription of these two genes and the binding activity of the heat shock transcription factor to the heat shock element. Culturing rat hepatocytes in either L-15 or Williams E resulted in a decrease in the levels of the mRNA transcripts for catalase and glutathione peroxidase and the activities of these two enzymes. However, the expression of Cu/Zn-superoxide dismutase, i.e., the level of the mRNA transcript or the enzymatic activity, did not change appreciably when hepatocytes were cultured for up to 48 hours. The decline in catalase and glutathione peroxidase expression in the cultured hepatocytes was correlated with a decrease in the GSH/GSSG ratio and an increase in lipid peroxidation. These data show that the expression of several genes involved in cellular protection change when hepatocytes are placed in primary cultures. Therefore, one must be careful in extrapolating from primary cultures to the liver in vivo, especially when studying processes that might be affected by heat shock proteins or antioxidant enzymes.

Animals↗
PubMed1996

Expression and analysis of a bacterial poly(hydroxyalkanoate) synthase in insect cells using a baculovirus system.

An improved method for expression of poly-beta-hydroxyalkanoate (PHA) synthase from Alcaligenes eutrophus has been developed using the baculovirus Autographa californica nuclear polyhedrosis virus (AcMNPV) in BTI-TN-5B1-4 Trichoplusia ni cells which results in high level production of active PHA synthase. Confirmation of expression of authentic PHA synthase was obtained by Western analysis which also revealed the presence of several apparent proteolytic cleavage products. N-terminal sequence data were obtained from the 64-kDa protein which verified its identity. The PHA synthase produced in this system constitutes approximately 50% of total protein after 60 h of viral infection and is found approximately equally distributed in both soluble and membrane-associated fractions. The expression level allowed rapid purification of the soluble form of PHA synthase to approximately 90% homogeneity in a single liquid chromatography step on hydroxylapatite. Using a direct spectrophotometric assay, analyses show that the enzyme has a pH optimum of 8.5, exhibits a concave-up Lineweaver-Burk plot, and a correlation between enzyme concentration and specific activity. Over 1000 units of soluble enzyme were obtained from a 250-ml culture of T. ni cells with an apparent initial specific activity of 12 mumol min-1 mg-1. The amount of PHA synthase activity is significantly higher than previously obtained from much larger bacterial cultures. The method described here should provide a general approach for the expression of active PHA synthases from a variety of bacterial sources to facilitate substrate specificity and mechanistic studies of these intriguing proteins.

Acyl Coenzyme A↗
PubMed1996

Isolation and structure of hemibastadinols 1-3 from the Papua New Guinea marine sponge Ianthella basta.

Further investigation of the Bismarck Archipelago (Papua New Guinea) marine sponge Ianthella basta for biologically active constituents has led to the isolation of hemibastadins 1 (2), 2 (3), and 3 (4) and the new brominated tyrosine derivatives hemibastadinols 1-3 (9, 13, and 14). Isolation and structure elucidation of the monomethyl ether derivatives (7 and 8) of hemibastadins 1 and 2 and the 3-bromotyramine amide of oxalic acid amide (1a) concluded our chemical investigation of I. basta. The hemibastadins and hemibastadinols represent important biosynthetic links to a series of bromotyrosine tetramers collectively known as the bastadins. The antimicrobial activity of the bastadins, hemibastadins, and hemibastadinols is summarized.

Animals↗
PubMed1996

Laparoscopic fundoplication.

Most reports on laparoscopic fundoplication are from large, tertiary referral medical centers. Presented here is an experience by a single surgeon (M.E.F.) in community hospitals with 74 cases. All patients had esophagitis. All but two patients were Visick grade IV off medication. All patients had an incompetent lower esophageal sphicter. Four with abnormally low esophageal contractions underwent a Toupet procedure; the rest had a Nissen fundoplication. The largest estimated blood loss was 300 cc. One case (1.4%) had to be converted intraoperatively to an open procedure because of bleeding from an iatrogenic liver laceration. There were two minor complications (a urinary tract infection and a pneumothorax) and one death (massive liver necrosis with an otherwise unremarkable post mortem, thus it was felt to be due to anesthesia). The mean length of hospital stay was 2.8 +/- 0.21 days. Eighty-nine percent of the operations totally relieved reflux. Nineteen patients (26%) had mild, early postoperative dysphagia, gas bloat, and/or early satiety. Four patients did not get any improvement in their reflux, three still require chronic medication, and one underwent a redo open fundoplication. Three early patients had severe, new-onset postoperative dysphagia secondary to too tight a fundoplication. Attention must be focused on creating a loose wrap, a "floppy" Nissen by routine division of the short gastric vessels and the use of a large dilator in the esophagus when the fundoplication is constructed. Laparoscopic fundoplication is technically feasible, safe, and effective in a community hospital and does not require a large, tertiary referral medical center.

Adolescent↗