Biomedical subjects

M A Johnson

Publications and source records attributed to M A Johnson.

At least 127 records · Page 7Linked to original sources

PubMed1999

Health characteristics of elderly personal care home residents.

The purpose of this descriptive study was to explore the health characteristics of elderly personal care home residents. Personal care homes are community-based facilities that provide living arrangements, assistance with basic needs and protective oversight. Personal care home providers were interviewed regarding the health status of 80 elderly residents. The most frequent ADL needs were bathing, personal hygiene and dressing. Thirty-seven per cent of the residents had some bladder incontinence. Eighty-two per cent of residents needed some help with medication management. Over half of the residents had some cognitive impairment. These findings support the proposition of increased prevalence of cognitive impairment in personal care home residents as compared to the first studies a decade ago. The combination of functional deficits and cognitive impairment indicates that these elderly residents may have unmet health needs. The role of the registered nurse in this environment is discussed.

Activities of Daily Living↗

PubMed1999

Chronic erosive herpes simplex virus infection of the penis, a possible immune reconstitution disease.

OBJECTIVE: To report a novel clinical presentation: a chronic erosive herpes simplex virus (HSV) infection of the penis which developed in AIDS patients following the commencement of highly active antiretroviral therapy (HAART). The lesions were unresponsive to antiviral treatments which had previously been effective, and this could not be accounted for in terms of increased antiviral resistance. DESIGN: Detailed case-note review and investigation of three cases which presented at two large HIV units in London. METHODS: Review of all histology with immunohistochemistry for HSV, HSV drug susceptibility assays, tissue typing and measurement of in vitro lymphocyte functional activity against HSV. RESULTS: The histology of the lesions was the same in each case, with the presence of HSV on immunohistochemistry and an unusual prominence of plasma cell and eosinophils in the inflammatory infiltrate. HSV-specific lymphoproliferative responses were normal in two cases, but subnormal in a third case. All individuals shared the HLA class I molecules B72 and Cw0202 and the class II allele DRB4. CONCLUSION: We believe this to be a previously unreported adverse consequence of HAART, the result of partial immune restoration, reminiscent of the the recently described syndrome of immune recovery vitritis.

AIDS-Related Opportunistic Infections↗

PubMed1999

Changing treatment patterns among patients with HIV: Royal Free Hospital 1987-97.

OBJECTIVE: Following the publication of results of large-scale clinical trials, antiretroviral treatment for HIV has changed dramatically. The aim of this study was to describe changes in antiretroviral treatment and the way treatments were combined among 1806 patients with HIV seen at a single centre at the Royal Free Hospital, London, UK. DESIGN AND METHOD: Each calendar year was divided into quarters, and the number of patients receiving treatment and participating in clinical trials was determined. RESULTS: The proportion of patients on no therapy decreased from over 90% at the beginning of 1988 to under 15% at the end of 1997. Monotherapy was the only form of treatment available before 1992 but its use dropped to 2% by the end of 1997. The standard of care at the end of 1997 was triple combination therapy, used in over 40% of patients. There were dramatic changes in the use of individual agents; use of zidovudine decreased from 50% during 1989 to 25% during 1997, while use of lamivudine and stavudine saw an exponential rise in 1997. The protease inhibitors were used in equal proportions in this clinic population; the use of dual protease therapy began in 1997 and was rising rapidly by the end of the year. CONCLUSIONS: There have been major changes in the use of antiretroviral therapy at this centre, particularly during 1996 and 1997. The long-term cost implications and side-effects of intensive treatment regimens remain to be addressed.

Adult↗

PubMed1999

An mtDNA mutation in the initiation codon of the cytochrome C oxidase subunit II gene results in lower levels of the protein and a mitochondrial encephalomyopathy.

A novel heteroplasmic 7587T-->C mutation in the mitochondrial genome which changes the initiation codon of the gene encoding cytochrome c oxidase subunit II (COX II), was found in a family with mitochondrial disease. This T-->C transition is predicted to change the initiating methionine to threonine. The mutation load was present at 67% in muscle from the index case and at 91% in muscle from the patient's clinically affected son. Muscle biopsy samples revealed isolated COX deficiency and mitochondrial proliferation. Single-muscle-fiber analysis revealed that the 7587C copy was at much higher load in COX-negative fibers than in COX-positive fibers. After microphotometric enzyme analysis, the mutation was shown to cause a decrease in COX activity when the mutant load was >55%-65%. In fibroblasts from one family member, which contained >95% mutated mtDNA, there was no detectable synthesis or any steady-state level of COX II. This new mutation constitutes a new mechanism by which mtDNA mutations can cause disease-defective initiation of translation.

Adult↗

PubMed1999

Pex17p is required for import of both peroxisome membrane and lumenal proteins and interacts with Pex19p and the peroxisome targeting signal-receptor docking complex in Pichia pastoris.

Pichia pastoris PEX17 was cloned by complementation of a peroxisome-deficient strain obtained from a novel screen for mutants disrupted in the localization of a peroxisomal membrane protein (PMP) reporter. PEX17 encodes a 267-amino-acid protein with low identity (18%) to the previously characterized Saccharomyces cerevisiae Pex17p. Like ScPex17p, PpPex17p contains a putative transmembrane domain near the amino terminus and two carboxyl-terminal coiled-coil regions. PpPex17p behaves as an integral PMP with a cytosolic carboxyl-terminal domain. pex17Delta mutants accumulate peroxisomal matrix proteins and certain integral PMPs in the cytosol, suggesting a critical role for Pex17p in their localization. Peroxisome remnants were observed in the pex17Delta mutant by morphological and biochemical means, suggesting that Pex17p is not absolutely required for remnant formation. Yeast two-hybrid analysis demonstrated that the carboxyl terminus of Pex19p was required for interaction with Pex17p lacking the carboxyl-terminal coiled-coil domains. Biochemical evidence confirmed the interaction between Pex19p and Pex17p. Additionally, Pex17p cross-linked to components of the peroxisome targeting signal-receptor docking complex, which unexpectedly contained Pex3p. Our evidence suggests the existence of distinct subcomplexes that contain separable pools of Pex3p, Pex19p, Pex17p, Pex14p, and the peroxisome targeting signal receptors. These distinct pools may serve different purposes for the import of matrix proteins or PMPs.

Amino Acid Sequence↗

PubMed1999

Age-related hearing loss, vitamin B-12, and folate in elderly women.

BACKGROUND: Hearing impairment is 1 of the 4 most prevalent chronic conditions in the elderly. However, the biological basis of age-related hearing loss is unknown. OBJECTIVE: The objective was to test the hypothesis that age-related hearing loss may be associated with poor vitamin B-12 and folate status. DESIGN: A thorough audiometric assessment was conducted in 55 healthy women aged 60-71 y. Hearing function was determined by the average of pure-tone air conduction thresholds at 0.5, 1, 2, and 4 kHz and was categorized into 2 groups for logistic regression analyses: normal hearing (<20 dB hearing level; n = 44) and impaired hearing (> or = 20 dB hearing level; n = 11). RESULTS: Mean age was the same (65 y) for the normal hearing and impaired hearing groups. Pure-tone averages were inversely correlated with serum vitamin B-12 (r = -0.58, P = 0.0001) and red cell folate (r = -0.37, P = 0.01). Women with impaired hearing had 38% lower serum vitamin B-12 (236 compared with 380 pmol/L, respectively, P = 0.008) and 31% lower red cell folate (425 compared with 619 nmol/L, respectively, P = 0.02) than women with normal hearing. Among participants who did not take supplements containing vitamin B-12 or folate, women with impaired hearing had 48% lower serum vitamin B-12 (156 compared with 302 pmol/L, respectively, P = 0.0007) and 43% lower red cell folate (288 compared with 502 nmol/L, respectively, P = 0.001) than women with normal hearing. CONCLUSION: Poor vitamin B-12 and folate status may be associated with age-related auditory dysfunction.

Aged↗

PubMed1999

Positive selection of novel peroxisome biogenesis-defective mutants of the yeast Pichia pastoris.

We have developed two novel schemes for the direct selection of peroxisome-biogenesis-defective (pex) mutants of the methylotrophic yeast Pichia pastoris. Both schemes take advantage of our observation that methanol-induced pex mutants contain little or no alcohol oxidase (AOX) activity. AOX is a peroxisomal matrix enzyme that catalyzes the first step in the methanol-utilization pathway. One scheme utilizes allyl alcohol, a compound that is not toxic to cells but is oxidized by AOX to acrolein, a compound that is toxic. Exposure of mutagenized populations of AOX-induced cells to allyl alcohol selectively kills AOX-containing cells. However, pex mutants without AOX are able to grow. The second scheme utilizes a P. pastoris strain that is defective in formaldehyde dehydrogenase (FLD), a methanol pathway enzyme required to metabolize formaldehyde, the product of AOX. AOX-induced cells of fld1 strains are sensitive to methanol because of the accumulation of formaldehyde. However, fld1 pex mutants, with little active AOX, do not efficiently oxidize methanol to formaldehyde and therefore are not sensitive to methanol. Using these selections, new pex mutant alleles in previously identified PEX genes have been isolated along with mutants in three previously unidentified PEX groups.

Alcohol Oxidoreductases↗

PubMed1999

Dysferlin is a plasma membrane protein and is expressed early in human development.

Recently, a single gene, DYSF, has been identified which is mutated in patients with limb-girdle muscular dystrophy type 2B (LGMD2B) and with Miyoshi myopathy (MM). This is of interest because these diseases have been considered as two distinct clinical conditions since different muscle groups are the initial targets. Dysferlin, the protein product of the gene, is a novel molecule without homology to any known mammalian protein. We have now raised a monoclonal antibody to dysferlin and report on the expression of this new protein: immunolabelling with the antibody (designated NCL-hamlet) demonstrated a polypeptide of approximately 230 kDa on western blots of skeletal muscle, with localization to the muscle fibre membrane by microscopy at both the light and electron microscopic level. A specific loss of dysferlin labelling was observed in patients with mutations in the LGMD2B/MM gene. Furthermore, patients with two different frameshifting mutations demonstrated very low levels of immunoreactive protein in a manner reminiscent of the dystrophin expressed in many Duchenne patients. Analysis of human fetal tissue showed that dysferlin was expressed at the earliest stages of development examined, at Carnegie stage 15 or 16 (embryonic age 5-6 weeks). Dysferlin is present, therefore, at a time when the limbs start to show regional differentiation. Lack of dysferlin at this critical time may contribute to the pattern of muscle involvement that develops later, with the onset of a muscular dystrophy primarily affecting proximal or distal muscles.

Amino Acid Sequence↗

PubMed1999

Respiratory infections in immunocompromised patients.

HIV disease has been dramatically reduced in the developed world by the introduction of highly active antiretroviral therapy, with implications that prophylactic therapy against opportunistic infections may be stopped; however, tuberculosis is an escalating problem in the HIV-infected and HIV-noninfected populations worldwide. Compliance with effective treatment regimens, especially through directly observed therapy, remains the cornerstone of tuberculosis control strategies. Although tuberculosis prophylaxis is of benefit for tuberculin skin reactors with HIV in the developed world, several reservations are voiced about this approach in resource-poor settings. Recent advances in technology, particularly in antigen-specific systems, have revolutionized the understanding of HIV immunology and helped to elucidate the mechanisms of pathogenesis in diseases such as cytomegalovirus. In bone marrow transplantation and solid-organ transplantation patients, quantitative polymerase chain reaction (PCR) to predict cytomegalovirus disease is an important advance, and patients who undergo bone marrow transplantation, CT scanning has proven useful in the diagnosis of pulmonary aspergillosis.

AIDS-Related Opportunistic Infections↗

PubMed1999

Lead as a risk factor for hypertension in women.

The relation between blood lead concentrations and hypertension, although suggestive, remains controversial. A recent case-control study examined the relation of blood and bone lead concentrations, used as a measure of long-term low-level lead exposure, to the risk of hypertension in women. An increase in patella lead concentrations from the 10th to the 90th percentile was associated with increased odds of hypertension of 1.86 using a backward-elimination logistic regression after adjusting for age, body mass index, dietary sodium intake, and family history of hypertension. Although more studies are needed, this study suggests that associations between lead and blood pressure do occur in women.

Bone and Bones↗

PubMed1999

Histochemical localisation of mitochondrial enzyme activity in human optic nerve and retina.

AIMS: To demonstrate the quantitative distribution of mitochondrial enzymes within the human optic nerve and retina in relation to the pathogenesis of ophthalmic disease. METHODS: Enucleations were performed at the time of multiple organ donation and the optic nerve and peripapillary retina immediately excised en bloc and frozen. Reactivities of the mitochondrial enzymes cytochrome c oxidase and succinate dehydrogenase were demonstrated in serial cryostat sections using specific histochemical assays. RESULTS: In the optic nerve the unmyelinated prelaminar and laminar regions were rich in both cytochrome c oxidase and succinate dehydrogenase. Myelination of fibres as they exited the lamina cribrosa was associated with an abrupt reduction in enzyme activity. Within the retina, high levels of enzyme activity were found localised within the retinal ganglion cells and nerve fibre layer, the outer plexiform layer, inner segments of photoreceptors, and the retinal pigment epithelium. CONCLUSIONS: Mitochondrial enzyme activity is preserved in human optic nerve and retina retrieved at the time of multiple organ donation. The distribution of enzyme activity within the eye has implications for the understanding of the pattern of ophthalmic involvement seen in mitochondrial diseases and the site of ganglion cell dysfunction in those patients with optic nerve involvement.

DNA, Mitochondrial↗

PubMed1999

Clinical pharmacokinetics of lamivudine.

Lamivudine (3TC), the negative enantiomer of 2'-deoxy-3'-thiacytidine, is a dideoxynucleoside analogue used in combination with other agents in the treatment of human immunodeficiency virus type 1 (HIV-1) infection and as monotherapy in the treatment of hepatitis B virus (HBV) infection. Lamivudine undergoes anabolic phosphorylation by intracellular kinases to form lamivudine 5'-triphosphate, the active anabolite which prevents HIV-1 and HBV replication by competitively inhibiting viral reverse transcriptase and terminating proviral DNA chain extension. The pharmacokinetics of lamivudine are similar in patients with HIV-1 or HBV infection, and healthy volunteers. The drug is rapidly absorbed after oral administration, with maximum serum concentrations usually attained 0.5 to 1.5 hours after the dose. The absolute bioavailability is approximately 82 and 68% in adults and children, respectively. Lamivudine systemic exposure, as measured by the area under the serum drug concentration-time curve (AUC), is not altered when it is administered with food. Lamivudine is widely distributed into total body fluid, the mean apparent volume of distribution (Vd) being approximately 1.3 L/kg following intravenous administration. In pregnant women, lamivudine concentrations in maternal serum, amniotic fluid, umbilical cord and neonatal serum are comparable, indicating that the drug diffuses freely across the placenta. In postpartum women lamivudine is secreted into breast milk. The concentration of lamivudine in cerebrospinal fluid (CSF) is low to modest, being 4 to 8% of serum concentrations in adults and 9 to 17% of serum concentrations in children measured at 2 to 4 hours after the dose. In patients with normal renal function, about 5% of the parent compound is metabolised to the trans-sulphoxide metabolite, which is pharmacologically inactive. In patients with renal impairment, the amount of trans-sulphoxide metabolite recovered in the urine increases, presumably as a function of the decreased lamivudine elimination. As approximately 70% of an oral dose is eliminated renally as unchanged drug, the dose needs to be reduced in patients with renal insufficiency. Hepatic impairment does not affect the pharmacokinetics of lamivudine. Systemic clearance following single intravenous doses averages 20 to 25 L/h (approximately 0.3 L/h/kg). The dominant elimination half-life of lamivudine is approximately 5 to 7 hours, and the in vitro intracellular half-life of its active 5'-triphosphate anabolite is 10.5 to 15.5 hours and 17 to 19 hours in HIV-1 and HBV cell lines, respectively. Drug interaction studies have shown that trimethoprim increases the AUC and decreases the renal clearance of lamivudine, although lamivudine does not affect the disposition of trimethoprim. Other studies have demonstrated no significant interaction between lamivudine and zidovudine or between lamivudine and interferon-alpha-2b. There is limited potential for drug-drug interactions with compounds that are metabolised and/or highly protein bound.

Absorption↗

PubMed1999

Interventions for disruptive behaviors. Use and success.

Health care providers deal with disruptions from geriatric patients routinely. Despite the negative impact on provider efficiency, provider-patient relations, and patient well-being, there have been no systematic clinical studies of the impact of disruptive behaviors on geriatric inpatient care. This article presents a taxonomy for these behaviors, applying them to a study of disruptive behaviors and concomitant nursing interventions on a geriatric evaluation and management (GEM) unit. The sample, consisting of 23 nursing staff (16 RNs, 4 LPNs, and 3 nurse aides), was followed over 8 weeks (five shifts per week, distributed randomly over day, evening, and night shifts). An experienced pair of RN observers logged all disruptive behaviors and the associated interventions employed by the nursing providers. The taxonomy was validated on 97 disruptive events (113 disruptive behaviors) initiated by 87 patients. The major findings of the study were: (a) disruptive behaviors are common on a GEM unit; (b) behaviors that disrupt care are recognized only 50% of the time by nursing staff; (c) interventions, when used singly, were found successful 45% of the time; (d) multiple simultaneous interventions may be more successful than single interventions but were used in only 16% of cases; and (e) selection of interventions may be associated with staff education level.

Aged↗

PubMed1999

Quantitative changes in cytomegalovirus DNAemia and genetic analysis of the UL97 and UL54 genes in AIDS patients receiving cidofovir following ganciclovir therapy.

Five AIDS patients with cytomegalovirus (CMV) retinitis who had received ganciclovir (GCV) therapy were followed with serial blood sampling to detectchanges both in CMV load and in the genetic composition of genes UL97 and UL54 whilst receiving cidofovir (CDV) therapy. CDV neither reduced CMV load in blood nor prevented its quantitative resurgence during therapy. These effects were not explained by the initial presence or development of CDV-associated drug resistance mutations in UL54. In two patients, UL97 genotypic resistance to GCV involving either a L595S mutation or a deletion of amino acids 590-603 were present at the initiation of CDV and, in both patients, repopulation of CMV strains with wild-type UL97 sequences occurred during CDV therapy. These data are consistent with GCV-resistant strains containing UL97 mutations being less fit than their wild-type counterparts and so being able to persist only with the selective pressure of GCV.

Acquired Immunodeficiency Syndrome↗

PubMed1999

Response of asymptomatic cytomegalovirus viraemia to oral ganciclovir 3 g/day or 6 g/day in HIV-infected patients.

Reactivation of cytomegalovirus (CMV) following immunosuppression may result in the development of CMV disease and is associated with an increased risk of death. CMV viraemia detected by the polymerase chain reaction (PCR) precedes CMV disease in HIV-infected patients and identifies individuals at high risk of disease. Pre-emptive ganciclovir (GCV) therapy in patients who have evidence of CMV viraemia is effective in preventing disease. An open study was conducted to assess the response of CMV viraemia to oral GCV at a dose of 3 or 6 g/day for 28 days. HIV RNA was measured to determine if CMV inhibition affected HIV viral load. Fourteen patients were studied, three of whom entered both phases of the study. None of the patients had evidence of CMV disease at the time of entry into the trial; two patients developed CMV retinitis after completion of the trial. Oral GCV at both 3 and 6 g/day caused a decrease in CMV viral load in individual patients. However, a rebound in CMV viral load occurred in patients receiving the 3-g/day dose. None of the patients receiving oral GCV 3 g/day became PCR negative after 21 days compared with six of eight patients receiving 6 g/day. Five of eight patients (63%) receiving GCV 6 g/day were concurrently taking protease inhibitors compared with two of nine (22%) receiving 3 g/day. Ten patients remained PCR negative throughout follow up. No change was found in HIV viral load during receipt of GCV at either dose. Thus, oral GCV is effective in reducing CMV viral load, but a dose of 3 g/day is insufficiently potent for pre-emptive therapy.

AIDS-Related Opportunistic Infections↗

PubMed1999

Prevalence of long-term BK and JC excretion in HIV-infected adults and lack of correlation with serological markers.

The natural history of polyomavirus infection, and sensitivity of diagnostic assays remain unclear. A stratified group of 94 human immunodeficiency virus (HIV)-infected patients was studied for both virological and serological markers of active infection with both JC virus and BK virus. JC DNA was detected in the urine of 18 of 81 (22%) patients and BK DNA in 30 (37%) patients. Whilst patients with a low CD(4) cell count (P =.009), CD(4)/CD(8) ratio (P =.031) and beta2M concentration (P =.042) were significantly more likely to be excreting BK, JC excretion did not correlate with any of the immunological markers measured. Furthermore, when all the immunological factors were taken into account, there was no association between either BK or JC excretion and age of the patient (P =.149 for BK, P = 0.891 for JC). BK IgM antibody was detected in only 3 of 30 (10%) BK excretors. JC IgM was detected in 5 of 18 (27. 7%) JC excretors but also in 11 of 63 (17.5%) patients without demonstrable JC excretion. Therefore IgM was a very poor indicator of viruria. One year follow-up on a subset of patients showed that both DNA detection in urine and IgM antibody remain stable over many months despite falling CD(4) cell counts, and would indicate that events leading to enhanced viral production probably occur early after HIV infection. Replication of JC virus in the brain leading to the onset of progressive multifocal leukoencephalopathy (PML) could not be predicted using any of the markers studied.

Adult↗

PubMed1999

Do people attending a same day testing clinic discuss their need for a HIV test with their GP?

In the United Kingdom, people with HIV infection present with advanced disease and general practitioners (GPs) are currently an underused resource for HIV testing. We describe the reasons for using an open-access clinic rather than primary care for testing for HIV. People attending the clinic were asked to complete a questionnaire asking about GP registration, access, and whether HIV testing was discussed in primary care. Despite access to GPs, HIV testing in primary care was rarely discussed. If HIV testing is to move to a general practice setting, GPs could address the issues, such as the recording of sensitive information in notes, future life insurance, and confidentiality, which this report identifies as the main barriers for using primary care.

Family Practice↗

PubMed1999

Leiomyosarcoma of the colon: a second malignant neoplasm after treatment for a Wilms' tumor.

Leiomyosarcoma of the colon is a rare malignancy. We report the case of a 33-year-old woman with a leiomyosarcoma of the colon occurring as an intussusception 30 years after receiving abdominal irradiation for a Wilms' tumor. A review of the prior and current treatment for Wilms' tumor is discussed, as well as the association between second malignancies and abdominal irradiation. Leiomyosarcoma of the colon usually presents in the fifth and sixth decades of life and is more common in men. The most common symptom is pain. Ninety per cent are diagnosed at surgery for treatment of bleeding, perforation, or obstruction. Surgery remains the primary treatment. Leiomyosarcomas of the gastrointestinal tract are radioresistant, and adjuvant chemotherapy has shown no survival benefit. The overall prognosis is poor, with mean 5-year survival of 28 per cent. General surgeons need to be aware of the possibility of second malignant neoplasms after primary treatment of childhood cancers. Proper reporting is essential to study the long-term effects of early treatment of childhood cancers and in predicting the best treatment outcomes for these patients.

Adult↗