Biomedical subjects
J Morgan
Publications and source records attributed to J Morgan.
Perturbation of the CuA site in cytochrome-c oxidase of Paracoccus denitrificans by replacement of Met227 with isoleucine.
Subunit II of cytochrome-c oxidase contains a redox centre, CuA, with unusual spectroscopic properties; this site consists of two copper atoms and acts as the entry point for electrons from cytochrome c. We have constructed a site-directed mutant of cytochrome-c oxidase from Paracoccus denitrificans in which the CuA site has been disturbed by replacement of Met227 with isoleucine. The purified, fully assembled enzyme complex has been investigated with various techniques including metal analysis, EPR and visible spectroscopies, steady-state and fast kinetics. The stoichiometry of the metals in the enzyme remains unchanged but a clear perturbation of the CuA site can be observed in the EPR and near-infrared optical spectra. It is concluded that in the mutant CuA is still binuclear but that the two nuclei are no longer equivalent, converting the delocalized [Cu(1.5)....Cu(1.5)] centre of the wild type into a localized [Cu(I)....Cu(II)] system. Changes in the overall kinetics of the mutant are correlated with a diminished electron transfer rate between CuA and heme alpha.
A randomised controlled study of close monitoring of vulnerable psychiatric patients.
The care programme approach was introduced in mental health services in the UK in 1991. It was intended to improve the quality of care and prevent patients losing contact with care services and, by implication, to reduce psychiatric admissions. We did a study to find out if the approach worked. 400 patients from a London inner-city area who had been identified as psychiatrically vulnerable and included on a case register of patients with special needs were randomised into two groups of 200 each. One group received close supervision by nominated key-workers (as recommended in the care programme approach of the UK Department of Health), and the other received standard follow-up from psychiatric and social services. Outcome was recorded after eighteen months. Data on 393 patients was available for analysis. Of 197 patients allocated to standard care, 64 (32.5%) were lost to follow-up compared with 40 (20.4%) of 196 patients receiving close supervision (p = < 0.005). However, patients under close supervision had significantly more admissions (30% vs 18%, chi 2 = 7.61, p < 0.01) and spent 68% more days in hospital than the standard group. The findings of greater hospital-bed use, which differ from those of studies with community-based psychiatric teams, suggest that close supervision by a single key worker, as recommended in the care programme approach, will lead to greater success in maintaining contact with vulnerable patients, but is likely to lead to more psychiatric admissions.
Diminished expression of insulin-like growth factor (IGF) binding protein-5 and activation of IGF-I-mediated autocrine growth in simian virus 40-transformed human fibroblasts.
The reduced growth factor requirements of murine fibroblasts transformed by simian virus 40 (SV 40) have been attributed to insulin-like growth factor (IGF)-I induction by T antigen and consequent activation of IGF-I receptor signaling. The present study shows that the autonomous growth of SV 40-transformed human fibroblasts also requires type-I IGF-I receptor activation but that this is not due to de novo induction of IGF-I gene expression since untransformed human fibroblasts, which fail to proliferate in the absence of serum, also showed IGF-I gene expression under serum-free conditions. DNA synthesis assays confirmed that untransformed cells were responsive to exogenous IGF and indicated that transformed cells were already maximally stimulated. In untransformed fibroblasts, IGF binding was principally to abundant membrane-associated IG-FBP-5, whereas in transformed fibroblasts this protein was minimally expressed, and IGF binding was to IGF receptors. Loss of detectable membrane-associated IG-FBP-5 in transformed cells was associated with diminished IGFBP-5 gene expression and with loss of IGF-II gene expression. Exogenous IGFBP-5 associated with the membranes of transformed cells and inhibited the autocrine growth of these cells. These findings suggest that loss of IGFBP-5 in SV 40-transformed fibroblasts facilitates interaction of endogenously produced IGF-I with the IGF-I receptor and increases their sensitivity to autocrine stimulation.
Draining ulcers with lymphadenopathy. Metastatic basal cell carcinoma.
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Ambulatory hemorrhoidectomy with CO2 laser.
PURPOSE: This study was undertaken to evaluate ambulatory hemorrhoidectomy using the CO2 laser. METHODS: Ninety consecutive patients (50 males, 40 females), 80 percent of whom had second or third degree hemorrhoids, had ambulatory hemorrhoidectomy performed with a CO2 laser in the left lateral Sims position under local anesthesia and intravenous sedation. Dissection was entirely performed with the CO2 laser using an open technique. RESULTS: One patient with polycythemia vera was admitted subsequently for secondary hemorrhage. All but three patients had healed within four weeks. No long-term sequelae were encountered. CONCLUSION: These results compare favorably with those obtained by others and show that ambulatory laser hemorrhoidectomy may simplify management in selected patients.
Association between severity of illness and mortality from nosocomial infection.
BACKGROUND: For the years 1987 through 1992, a study was undertaken to analyze nosocomial infection mortality data and to stratify risk according to severity of underlying illness to compare with published data from the Centers for Disease Control and Prevention. METHODS: Nosocomial infections that contributed to or caused death were identified. In addition, during 1990 through 1992, severity of illness was determined as the subjective estimate of the risk of death or lack of risk of death during the current hospital admission before the onset of the nosocomial infection. These groups were named +SIC and -SIC, respectively. RESULTS: It was determined that the data from death certificates in cases of known nosocomial infection were not sufficient to determine whether nosocomial infection contributed to or caused death. There was a 24% increase in cases of nosocomial infection contributing to or causing death when a physician reviewed deaths in patients with nosocomial infections who did not have a diagnosis of nosocomial infection listed on the death certificate. The rates for nosocomial infections contributing to or causing death are as follows: nosocomial pneumonia, 20%; and bloodstream infections, 19%. In patients who died and had severity of illness determination, there was a statistically significant difference in the rates of nosocomial infections contributing to or causing death between -SIC and +SIC groups for both nosocomial pneumonia and bloodstream infections. The rates for bloodstream infections were as follows: -SIC, 5%; and +SIC, 21%. For nosocomial pneumonia, the rates were as follows: -SIC, 13%; and +SIC, 23%. CONCLUSION: In published reports from the Centers for Disease Control and Prevention, a rate of 13% is given for nosocomial pneumonia and bloodstream infections contributing to or causing death; however, there is no stratification for severity of illness in these reports. The presence of life-threatening illness before the onset of nosocomial pneumonia or bloodstream infection accounts for most deaths among our patients. For valid comparisons, mortality outcome data for nosocomial infections should be stratified for risk according to severity of underlying illness.
Insulin-like growth factor (IGF) and IGF binding proteins in growth hormone dysregulation and abnormal glucose tolerance in small cell lung cancer patients.
Growth hormone (GH) regulation, glucose tolerance and serum concentrations of insulin-like growth factor (IGF) and IGF binding proteins (IGFBP) have been investigated in small cell lung cancer (SCLC) patients. Elevated serum GH was observed in the patient and smoking control groups but not in non-smoking control subjects. Glucose suppression of GH was observed in the few SCLC patients with raised basal GH but most SCLC patients exhibited a paradoxical increase in GH following oral glucose. Abnormal glucose tolerance and insulin resistance with respect to plasma glucose was observed in most patients. Patients showing GH dysregulation exhibited higher serum concentrations of IGFBP-2 than those showing no increase in GH. Abnormal glucose tolerance was associated with decreased serum concentrations of IGF-I. Given reports of elevated IGFBP secretion in SCLC and inhibition of IGF-I bioactivity by IGFBPs, these findings may indicate that increased serum IGFBPs disrupt IGF-I regulation of GH secretion and glucose homeostasis.
Oxygen availability in critical illness--an investigation using the oxygen status algorithm.
Using the oxygen status algorithm of Siggaard-Andersen to derive 2,3-diphosphoglycerate concentrations and parameters of oxygen extractivity, 143 arterial blood specimens from 73 ICU patients were compared with 119 venous blood specimens from 119 healthy outpatients. The venous extractivity parameters were calculated by arbitrarily assigning an oxygen tension of 90 mmHg to each specimen. There were no significant differences in 2,3-diphosphoglycerate, but the mean concentration of extractable oxygen corrected for low haemoglobin values (cx/cHb) was significantly greater in the ICU patients (males: 0.017 +/- 0.004 mmol/g, females: 0.016 +/- 0.004 mmol/g) than in the healthy outpatients (males and females: 0.014 +/- 0.001 mmol/g, p < 0.05). This reduction in haemoglobin-oxygen affinity was attributed to the high incidence of acidaemia in the ICU specimens (mean pH 7.36 +/- 0.08), despite a reduced mean 2,3-diphosphoglycerate concentration in the ICU acidaemic specimens (when pH < 7.35, mean 2,3-diphosphoglycerate concentration was 4.9 +/- 1.6 mmol/L; when 7.35 < or = pH < or = 7.45: mean 2,3-diphosphoglycerate concentration was 5.7 +/- 1.6 mmol/L, p < 0.05). Hypophosphataemia had no demonstrable effect on 2,3-diphosphoglycerate concentrations or extractivity parameters in the ICU patients. We conclude that oxygen release from haemoglobin to the tissues in critical illness is enhanced because of a tendency to acidaemia.
The role of transferrin receptor (CD71) in photodynamic therapy of activated and malignant lymphocytes using the heme precursor delta-aminolevulinic acid (ALA).
Endogenously generated protoporphyrin IX (PpIX) from exogenous ALA can be an effective photosensitizer. PpIX accumulation is inversely dependent on available intracellular iron, which is required for the conversion of PpIX to heme. Iron also is necessary for cell replication. Since iron can be toxic, intracellular iron levels are tightly controlled. Activated and proliferating cells respond to the demand for intracellular iron by upregulating membrane expression of the transferrin receptor (CD71) which is needed for iron uptake. We predicted that activated lymphocytes (CD71+) would preferentially accumulate PpIX because of their lower intracellular iron levels and because of competition for iron between ALA-induced heme production and cellular growth processes. Thus, the CD71+ cells could serve as PDT targets. Stimulation of human peripheral blood lymphocytes (PBL) with the mitogens, phytohemagglutinin A, concanavalin A and pokeweed prior to incubation with ALA results in PpIX accumulation correlating with level of activation. Activated lymphocytes expressing high levels of surface CD71 transferrin receptors generated more PpIX than those with low CD71 expression. Incubating activated cells in transferrin depleted medium (thereby decreasing the iron availability) further increased PpIX levels. Malignant, CD71+ T lymphocytes from a patient with cutaneous T-cell lymphoma (CTCL)/Sezary syndrome also accumulated increased PpIX levels in comparison to normal lymphocytes. PDT of activated lymphocytes and Sezary cells after ALA incubation demonstrated preferential killing compared to normal, unstimulated PBL. These findings suggest a possible mechanism for the selectivity of ALA PDT for activated CD71+ cells. They also indicate a clinical use for ALA-PDT in therapy directed towards the malignant lymphocytes in leukemias and lymphomas, and as animmunomodulatory agent.
Office abortion services for women: private physician providers.
Research suggests that private physician providers of office abortions and the women who seek their services are not included in nationwide surveys of abortion statistics. This study describes the demographic characteristics of private physicians and the prevalence of abortions performed in their offices in Los Angeles County, California, a state in which office abortions are prohibited by law. Factors that influence physicians' decisions to provide the service, as well as the age and ethnicity of the office abortion recipients, are examined. Of 1,004 California Medical Association members who practiced obstetrics and gynecology in Los Angeles County during 1990, 49% returned anonymous, confidential surveys. Seventy percent of physicians had performed at least one abortion in California, and 29% were currently providing this service in their offices. Physician gender, age, ethnicity, and religion were associated with performing abortions. The average abortion patient was not young and ethnic, but White, middle-class, and in her mid- to late twenties. The implications of these findings are discussed.
Breastfeeding in the 1990s.
Midwives are the most important advisers on infant feeding methods. Advice on infant feeding needs to be given early. Advice on maintenance of lactation is essential. Supportive hospital surroundings are important. Change from one formula to another mirrors the change from breast to bottle. Research is needed into mothers' reasons for changing infant feeding method.
Infant feeding practices in the 1990s.
A survey of infant feeding practices reveals that many of the current government recommendations are not being adopted by parents. Jane Morgan and Jacqueline Stordy describe the study findings. The publication of the 1994 Coma report on infant weaning should provide a timely opportunity for health visitors to take the initiative in educating and informing parents on good infant feeding practices, they suggest.
A simple quality control protocol for haemoximetry using standard p50.
We have designed a quality control tool for haemoximetry using the principle that standard p50, calculated from blood gas and haemoximetry measurements using the Siggaard-Andersen algorithm, remains unchanged when a specimen of venous blood is oxygenated progressively to 97% saturation of haemoglobin. If the haemoximeter is inaccurate, progressively larger deviations of standard p50 from the constant value occur above 80% saturation. Deviations too small to be detected by analysis of quality control materials comprised of non-haemoglobin dyes and yet sufficient to cause significant errors in derived extractivity parameters can be detected by this method. The suggested protocol is easy to perform, and is recommended as a quality control tool for blood gas analyser/haemoximeters used to determine arterial extractivity parameters.
Oxidation of low density lipoprotein by iron or copper at acidic pH.
Oxidized low density lipoprotein (LDL) may play a significant role in atherosclerosis. We have investigated the effect of pH on the oxidation of LDL by iron or copper. When LDL was oxidized by iron in the presence of cysteine in either Hanks' balanced salt solution (HBSS) or Ham's F-10 medium, an acidic pH greatly decreased the lag period and increased the rate of formation of hydroperoxides and thiobarbituric acid-reactive substances (TBARS), and increased its uptake by macrophages. There was a dose-dependent increase of LDL oxidation at acidic pH in the presence of increasing concentrations of cysteine. When LDL was oxidized by copper in HBSS, an acidic pH increased the lag phase before the rapid formation of conjugated dienes, hydroperoxides, and TBARS, but increased its uptake by macrophages. Similar results were obtained using Ham's F-10 medium. Cysteine (100 microM) inhibited the modification of LDL by copper in HBSS at both pH 7.4 and 5.5 As atherosclerotic lesions may be acidic, these observations may help to explain why LDL oxidation occurs locally at these sites.
Purification of histamine receptor proteins from detergent-solubilized human peripheral blood mononuclear cells.
Histamine is released from mast cells and basophils by either immunological or nonimmunological mechanisms. Histamine, which is the most potent short acting mediator released from these cells, exerts its diverse biological actions by binding to cell surface histamine receptors. We report the affinity purification of histamine receptor proteins from Triton X-100 solubilized peripheral human blood mononuclear cells which include lymphocytes and monocytes. Three different designs of histamine affinity columns were constructed; all three resulted in the same material being eluted. This consisted of bands which on SDS-PAGE after boiling and reduction had the following molecular weights: 193K, 84K, 58K, 48K, 37K, and 16K. The most abundant bands were of molecular weights 193K, 48K, and 16K, and these were disulfide bonded together to form a high molecular weight complex. (The 58K band was present in lower amounts than the others, and in only a few fractions. It had the same molecular weight as the dimeric form of histamine methyltransferase which is present in small amounts in mononuclear cells and may therefore have copurified.) The histamine binding proteins described in this report were purified by conventional affinity chromatography, rather than by an expression cloning approach which obviates the use of any protein chemistry. Consequently, we had the advantage of being able to verify the histamine binding specificity of our purified proteins directly and with several independent assays as follows. The histamine binding specificity of all three columns was established by specific elution with histamine, by preabsorption of crude cell extract with excess free histamine prior to column application, and by comparison with control columns. Independent determination of the binding specificity, using a radioreceptor dot blot assay, of the eluate containing only the 193K, 48K, and 16K disulfide-linked subunits confirmed that the purified material bound specifically to [3H]histamine and that a 300-500-fold degree of purification from tissue extract had been obtained. Following cell surface radioreceptor cross-linking of radiolabeled histamine to intact mononuclear cells, the 16K band was detected, indicating it to be the ligand-binding subunit for histamine. These same three proteins were purified from T lymphocyte and monocytoid cell lines, indicating that both lymphocyte and monocyte subsets of mononuclear cells express these proteins.(ABSTRACT TRUNCATED AT 400 WORDS)
Time-resolved fluorescence spectroscopy and intracellular imaging of disulphonated aluminium phthalocyanine.
Spectroscopic studies were carried out on the photosensitizer disulphonated aluminium phthalocyanine (AlS2Pc) which has prospective applications in photodynamic therapy. The fluorescence lifetimes of AlS2Pc were measured in a range of model systems and cultured leukaemic cells using laser excitation and time-correlated, single-photon-counting detection. In an investigation of non-covalent protein binding, we studied AlS2Pc in the presence of human serum albumin (HSA) in 0.1 M phosphate-buffered saline at pH 7.4. On addition of excess concentrations of HSA, small red shifts in the fluorescence and absorbance spectra were observed, together with an increase in fluorescence polarization anisotropy, consistent with binding of the phthalocyanine. Fluorescence decays could be resolved into two lifetimes for bound AlS2Pc with a dominant component of 5.5 ns and a minor component of 1 ns. Fluorescence imaging and time-resolved microfluorometry were carried out on intracellular AlS2Pc using leukaemic K562 cells. Microscopic imaging with a charge-coupled device (CCD) camera revealed that AlS2Pc fluorescence predominated in a discrete perinuclear region which was then probed selectively by a focused laser spot for fluorescence lifetime measurements. Bi-exponential decays with lifetime components of 6.1 and 2.2 ns were observed. On irradiation at 633 nm, the fluorescence intensity increased initially and subsequently declined due to photodegradation.
Differences in hormonal and renal vascular responses between normotensive patients with autosomal dominant polycystic kidney disease and unaffected family members.
We tested the hypothesis that overactivity of the renal and systemic renin-angiotensin system is important to the pathogenesis of hypertension in autosomal dominant polycystic kidney disease (ADPKD). Up to 21 normotensive subjects with ADPKD and creatinine clearance > 70 ml/min/1.73 m2 were compared to 12 unaffected controls from the same families. Blood pressure, serum chemistry, sodium excretion, plasma renin and serum aldosterone and atrial natriuretic peptide (ANP) levels were measured at baseline, after acute sodium depletion, and after chronic higher sodium intake with and without enalapril. Effective renal plasma flow was measured by paraaminohippurate clearance in the higher sodium state, before and during an intravenous infusion of angiotensin II at 3 ng/kg/min. This was to test whether, by analogy to non-modulating essential hypertension, renal blood flow would fall to a lesser extent in the ADPKD subjects. The groups were comparable at baseline apart from a higher supine mean arterial pressure in the ADPKD group (median 91 vs. 81 mm Hg, P = 0.002). There were no significant differences between ADPKD and control subjects in blood pressure or hormonal response to sodium depletion. During chronically higher sodium intake, serum ANP was significantly higher (median 130 vs. 81 ng/liter, P = 0.0006) and plasma renin tended to be higher (median 20.5 vs. 13.5, P = 0.08) in ADPKD than in control subjects. The ADPKD group had a higher renal vascular resistance (median 7420 vs. 5915 dyn.sec.cm-5, P = 0.009) before angiotensin, but tended to have a lower percentage rise in resistance during angiotensin (median 31.5 vs. 46, P = 0.14).(ABSTRACT TRUNCATED AT 250 WORDS)