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Biomedical subjects

M A Johnson

Publications and source records attributed to M A Johnson.

At least 163 records · Page 9Linked to original sources
PubMed1998

Copper, iron, zinc, and manganese in dietary supplements, infant formulas, and ready-to-eat breakfast cereals.

High intakes of iron, zinc, or manganese can interfere with copper absorption. Thus, the purpose of this study was to determine whether the amounts and chemical forms of iron, zinc, manganese, and copper added to food products and nutritional supplements might pose a threat to copper status. More than 25% of the vitamin and mineral supplements examined contained no copper, 40% contained the poorly absorbed cupric oxide, and < 30% contained a highly bioavailable form of copper such as cupric sulfate or cupric chloride. Nearly 40% of the prenatal supplements examined contained both iron and zinc without a nutritionally significant amount of copper. More than 80% of the infant formulas examined had ratios of iron to copper exceeding 20:1, which is higher than the recommended ratios of 10-17:1. None of the 40 ready-to-eat breakfast cereals examined were fortified with copper or manganese although 50% of these cereals contained > or = 25% of the reference daily intake for both iron and zinc. Copper availability could be improved by reformulation of several food products and supplements.

Biological Availability↗
PubMed1998

Demographic, clinical and social factors associated with human immunodeficiency virus infection and other sexually transmitted diseases in a cohort of women from the United Kingdom and Ireland. MRC Collaborative Study of women with HIV.

BACKGROUND: Clinical experience suggests many women with HIV infection have experienced no other sexually transmitted diseases (STD). Our objective was to test the hypothesis that a substantial proportion of women with HIV infection in the United Kingdom and Ireland have experienced no other diagnosed STD and to describe the demographic, clinical and social factors associated with the occurrence of other STD in a cohort of HIV infected women. METHOD: Analysis of cross-sectional baseline data from a prospective study of 505 women with diagnosed HIV infection. The setting was 15 HIV treatment centres in the United Kingdom and Ireland. The main outcome measures were occurrence of other STD diagnosed for the first time before and after HIV diagnosis. Data were obtained from interview with women and clinic notes. We particularly focused on occurrence of gonorrhoea, chlamydia and trichomoniasis after HIV diagnosis, as these are the STD most likely to reflect recent unprotected sexual intercourse. RESULTS: The women were mainly infected via heterosexual sex (n = 304), and injection drug use (n = 174). 151 were black Africans. A total of 250 (49.5%) women reported never having been diagnosed with an STD apart from HIV, 255 (50.5%) women had ever experienced an STD besides HIV, including 109 (21.6%) who had their first other STD diagnosed after HIV. Twenty-five (5%) women reported having had chlamydia, gonorrhoea or trichomoniasis diagnosed for the first time after HIV diagnosis, possibly reflecting unprotected sexual intercourse since HIV diagnosis. In all 301 (60%) women reported having had sex with a man in the 6 months prior to entry to the study. Of these, 168 (58%) reported using condoms 'always', 66(23%) 'sometimes' and 56 (19%) 'never'. CONCLUSIONS: Half the women in this study reported having never experienced any other diagnosed STD besides HIV. However, after HIV diagnosis most women remain sexually active and at least 5% had an STD diagnosed which reflect unprotected sexual intercourse.

Adolescent↗
PubMed1998

Dietary protein supplementation and recovery from femoral fracture.

A recent randomized, double-blind, placebo-controlled trial found that protein supplementation improved recovery from femoral fractures in an elderly population. A 6-month course of protein supplementation (20 g/day, 5 days/week) improved serum prealbumin and insulin-like growth factor I (IGF-I) concentrations, minimized bone loss, and decreased length of stay in rehabilitation facilities.

Aged↗
PubMed1998

Epidemiology of cerebral palsy in England and Scotland, 1984-9.

AIMS: To report on the epidemiology of cerebral palsy in England and Scotland, to provide information on the prevalence of cerebral palsy and the severity of the disability or any co-morbidity. METHODS: Cerebral palsy registers were compiled from multiple sources of ascertainment covering all of Scotland and the counties of Merseyside, Cheshire, Berkshire, Buckinghamshire, Northamptonshire and Oxfordshire in England. All cases of cerebral palsy born in 1984 to 1989, to mothers resident in the area, were included. Denominator number of live births and neonatal deaths for determining birthweight specific prevalence were obtained from birth and death registrations. Learning, manual, and ambulatory disabilities were graded for severity. Any co-existing sensory (hearing or visual) morbidity was also graded for severity. RESULTS: There were 789,411 live births in 1984-9, with 3651 neonatal deaths (neonatal mortality 4.6 per 1000 live births) and 1649 cases of cerebral palsy--a cerebral palsy prevalence of 2.1 per 1000 neonatal survivors. The birthweight specific cerebral palsy prevalence ranged from 1.1 per 1000 neonatal survivors in infants weighting > or = 2500 g to 78.1 in infants weighing < 1000 g. There was no significant time trend in prevalence of cerebral palsy in any of the birthweight groups, in contrast to the fall in neonatal mortality observed in all birthweight groups. Of the 1649 cases of cerebral palsy, 550 (33.4%) had severe ambulatory disability (no independent walking), 390 (23.7%) had severe manual disability (incapable of feeding or dressing unaided), 381 (23.1%) had severe learning disability (IQ < 50), 146 (8.9%) had severe visual disability (vision < 6/60 in the better eye) and 12 had severe hearing disability (> 70 dB loss). CONCLUSIONS: Registers fill an important gap left by the lack of routine data on the prevalence of disability in children. The ability to record trends in the prevalence and the severity of the disability should inform those who have responsibility for providing services for children with disabilities.

Cerebral Palsy↗
PubMed1998

Vigabatrin-associated retinal cone system dysfunction: electroretinogram and ophthalmologic findings.

OBJECTIVE: To determine the sources of vigabatrin-associated visual disturbances in patients treated for epilepsy. BACKGROUND: Vigabatrin is an extremely effective antiepileptic drug that selectively increases brain gamma-aminobutyric acid (GABA). Several patients recently developed constricted visual fields during vigabatrin treatment in the United Kingdom, indicating the possibility of GABA-associated retinal dysfunction. METHODS: Patients with visual symptoms treated chronically with vigabatrin at our center underwent visual evoked potentials (VEP), electroretinograms (ERG), and visual field and ophthalmologic examinations. RESULTS: Four of 38 patients treated with vigabatrin developed visual symptoms 2 to 40 months after starting the drug. Two patients complained of constricted visual fields and two had blurred vision. ERG demonstrated evidence of bilateral retinal dysfunction consistent with reduced inner retinal cone response in all four patients. Oscillatory potential responses were lost, suggesting impairment of the highly GABAergic amacrine cells. Two of the patients had normal VEPs and minimal findings on clinical ophthalmology examinations despite abnormal ERGs. Abnormal examination findings were narrowed retinal arteries, surface wrinkling retinopathy, and abnormal macular reflexes. One patient also had reduced rod photoreceptor function in the more symptomatic left eye. CONCLUSIONS: Visual field constriction and blurring during vigabatrin therapy is associated with retinal cone system dysfunction. Visual symptoms may represent selective vulnerability of retinas of affected patients to GABAergic effects of vigabatrin. The prevalence and course of retinal changes associated with vigabatrin therapy are important to determine in a larger group of patients.

Adult↗
PubMed1998

Research bronchoscopies do not adversely affect HIV-infected individuals' future health-care decisions.

STUDY OBJECTIVES: Asymptomatic HIV-infected individuals are increasingly recruited for studies involving invasive procedures such as bronchoscopy. We sought to determine the response to and outcome of a request for a research bronchoscopy in HIV-positive individuals with no respiratory disease, and whether this would adversely affect future decisions to have a medically indicated bronchoscopy. DESIGN AND SETTING: Prospective, semistructured, questionnaire-based study in a London teaching hospital HIV outpatient clinic. PARTICIPANTS: One hundred and seven consecutive HIV-infected eligible individuals. Thirty-one healthy volunteers served as a control group for the subjective response to bronchoscopy. MAIN OUTCOME MEASURES: Subjects' attitudes and responses to requests for bronchoscopy and subsequent behavior when they required medically indicated bronchoscopy. RESULTS: Seventy-five patients (70%) agreed to the procedure in principle, predominantly for altruistic reasons. Thirty-nine subjects underwent bronchoscopy. Five percent found it worse than expected; and 79% agreed to another research bronchoscopy (performed in 11 subjects approximately 2 years later). All patients said they would undergo bronchoscopy again for diagnostic purposes (required in seven during the study). When compared to a healthy volunteer population within the same study, postbronchoscopy symptoms were similar in frequency although somewhat different in nature. Subjects felt that a clear explanation of what was involved enhanced their participation in this research. CONCLUSIONS: Invasive research procedures such as bronchoscopy can be performed and are repeatable in a healthy HIV-infected population. Performance of procedures for research purposes does not appear to adversely affect future health-care decisions.

Adolescent↗
PubMed1998

Milk consumption in older Americans.

OBJECTIVES: The purpose of this study was to identify individual characteristics associated with types and frequency of milk consumption in older American adults. METHODS: A national probability-based sample (response rate = 91%) completed a telephone survey. Generalized logit and cumulative logit analyses were used to identify predictors of and barriers to fluid milk consumption in 494 elderly people. RESULTS: The likelihood of drinking skim or 1% milk rather than whole milk increased with nutrition knowledge, income, trying to reduce cholesterol intake, and being female (P < .05). Frequency of milk consumption was higher with nutrition knowledge, frequency of milk consumption during adolescence, and following a diabetic diet but was lower with milk intolerance. CONCLUSIONS: The present results could be used to develop intervention strategies for improving milk consumption rates among older adults. These strategies might focus on increasing elderly people's awareness of milk intolerance and lactose-reduced milk products and their concern about cholesterol. The relationship between current and adolescent milk consumption suggests that intervention strategies should begin early in life.

Adolescent↗
PubMed1998

DNA sequence of the fowl adenovirus serotype 10 short fiber gene.

The complete nucleotide sequence and map location of the short fiber gene of fowl adenovirus serotype 10 (FAV-10) strain CFA20 was determined. The coding sequence of the short fiber gene was found to be 1383 bp, encoding a putative polypeptide of 461 amino acids. The gene was located between 69.2 to 71.7 map units on the FAV-10 genome. A consensus splice acceptor site was located 30 bp upstream of the putative translation start codon and a polyA recognition sequence was located 24 bp downstream of the translation stop codon, signaling the end of late transcription unit five.

Adenoviridae↗
PubMed1998

Aspergillus: a rare primary organism in soft-tissue infections.

Nonclostridial necrotizing soft-tissue infections are usually polymicrobial, with greater than 90 per cent involving beta-hemolytic streptococci or coagulase-positive staphylococci. The remaining 10 per cent are usually due to Gram-negative enteric pathogens. We describe the case of a 46-year-old woman with bilateral lower extremity fungal soft tissue infections. She underwent multiple surgical debridements of extensive gangrenous necrosis of the skin and subcutaneous fat associated with severe acute arteritis. Histopathological examination revealed Aspergillus niger as the sole initial pathogen. Despite aggressive surgical debridement, allografts, and intravenous amphotericin B, her condition clinically deteriorated and she ultimately died of overwhelming infection. Treatment for soft-tissue infections include surgical debridement and intravenous antibiotics. More specifically, Aspergillus can be treated with intravenous amphotericin B, 5-fluorocytosine, and rifampin. Despite these treatment modalities, necrotizing fascitis is associated with a 60 per cent mortality rate. Primary fungal pathogens should be included in the differential diagnosis of soft-tissue infections.

Aspergillosis↗
PubMed1998

Changes in lung lymphocyte populations reflect those seen in peripheral blood in HIV-1 positive individuals.

We have investigated the level of lymphocytosis present in the lung of human immunodeficiency virus (HIV)-1+ infected patients with and without pulmonary disease and how changes in natural killer (NK), B and T-cells seen in peripheral blood (PB) compare with those seen in bronchoalveolar lavage fluid (BALF). Lymphocyte subpopulations and their expression of activation, cytotoxic markers and memory status were characterized by triple immunofluorescence. Macrophages accounted for over 80% of the BAL cells. Only three out of 72 patients had a lymphocyte percentage >30%. No statistically significant differences in the relative proportions of NK, CD4 and CD8 populations were seen in BALF when compared to PB, except for a twofold increase in the percentage of activated CD8 cells in BALF. The only differences in BALF populations between the HIV-1+ groups were a lower percentage of CD4+ cells, and a higher percentage of activated CD8+ cells in the patients with pneumonitis. In the present cohort of patients there was little evidence for an overall lymphocytosis in bronchoalveolar lavage fluid of HIV-1+ subjects. Changes observed in lymphocyte subsets of bronchoalveolar lavage fluid populations reflected those in peripheral blood, and were similar for patients with and without pneumonitis. Evidence of increased CD8 subset activity in bronchoalveolar lavage fluid did, however, emerge.

AIDS-Related Opportunistic Infections↗
PubMed1997

Survival after diagnosis of AIDS: a prospective observational study of 2625 patients. Royal Free/Chelsea and Westminster Hospitals Collaborative Group.

OBJECTIVE: To estimate median survival and changes in survival in patients diagnosed as having AIDS. DESIGN: Prospective observational study. SETTING: Clinics in two large London hospitals. SUBJECTS: 2625 patients with AIDS seen between 1982 and July 1995. MAIN OUTCOME MEASURES: Survival, estimated using lifetable analyses, and factors associated with survival, identified from Cox proportional hazards models. RESULTS: Median survival (20 months) was longer than previous estimates. The CD4 lymphocyte count at or before initial AIDS defining illness decreased significantly over time from 90 x 10(6)/1 during 1987 or earlier to 40 x 10(6)/1 during 1994 and 1995 (P < 0.0001). In the first three months after diagnosis, patients in whom AIDS was diagnosed after 1987 had a much lower risk of death (relative risk 0.44, 95% confidence interval 0.22 to 0.86; P = 0.017) than patients diagnosed before 1987. When the diagnosis was based on oesophageal candidiasis or Kaposi's sarcoma, patients had a lower risk of death than when the diagnosis was based on Pneumocystis carinii pneumonia (0.21 (0.07 to 0.59). P = 0.0030 and 0.37 (0.16 to 0.83), P = 0.016). Three months after AIDS diagnosis, the risk of death was similar in patients whose diagnosis was made after and before 1987 (1.02 (0.79 to 1.31), P = 0.91). There were no differences in survival between patients diagnosed during 1988-90, 1991-3, or 1994-5. CONCLUSIONS: In later years, patients were much more likely to survive their initial illness, but long term survival has remained poor. The decrease in CD4 lymphocyte count at AIDS diagnosis indicates that patients are being diagnosed as having AIDS at ever more advanced stages of immunodeficiency.

Acquired Immunodeficiency Syndrome↗
PubMed1997

Prevalence of anti-vif antibodies in HIV-1 infected individuals assessed using recombinant baculovirus expressed vif protein.

A 630 base pair fragment of the HIV-1 genome encompassing the entire vif open reading frame has been produced by the polymerase chain reaction and cloned into the baculovirus transfer vector pAcYM1. Extracts from insect cells infected with a recombinant baculovirus expressing the HIV-1 vif gene product were used in a radioimmunoassay to analyse 238 sera from HIV infected individuals for the presence of anti-vif antibodies. The overall prevalence of anti-vif antibodies in this group of patients was 25.3%. Stratification of the group according to CD4 levels showed that anti-vif antibodies were more prevalent in patients with CD4 counts below the median of the group (155 x 10(6) cells/L; P = 0.005). A significant increase in anti-vif antibodies was observed in patients with CD4 levels less than 280 x 10(6) cells/L (P < 0.01) and in patients with symptomatic HIV infection (P = 0.0003). However, there was no significant difference in the prevalence of anti-vif antibodies in patients stratified according to p24 antigen status. The implications of these findings in the context of HIV replication are discussed.

Acquired Immunodeficiency Syndrome↗
PubMed1997

Mitochondrial function in muscle from elderly athletes.

The extent to which mitochondria are involved in the aging process is controversial; much of the reported decline in mitochondrial oxidations in human skeletal muscle may be due to disease and inactivity rather than age. To study true aging, mitochondrial respiratory chain function was studied in 9 young and 12 elderly athletes. No significant deterioration with age was observed. If mitochondria are involved in aging, it must be through a more subtle mechanism than a global decline in respiratory chain activity.

Adult↗
PubMed1997

A novel mitochondrial tRNA phenylalanine mutation presenting with acute rhabdomyolysis.

We describe a patient who presented with acute rhabdomyolysis and had 68% cytochrome c oxidase (COX)-deficient fibers in skeletal muscle. Further investigations confirmed a respiratory chain defect that was associated with a novel heteroplasmic point mutation in the phenylalanine tRNA gene of the mitochondrial genome (mtDNA). Analysis of single muscle fibers revealed a significantly greater level of mutant mtDNA in COX-negative fibers. This is the first case of a mitochondrial tRNA gene point mutation presenting with acute rhabdomyolysis and recurrent myoglobinuria.

Acute Disease↗
PubMed1997

Nucleotide sequence of the left-terminus of infectious laryngotracheitis virus (Gallid herpesvirus 1) SA-2 strain.

The nucleotide sequence of 10.6 kilobase pairs (kbp) at the leftterminus of infectious laryngotracheitis virus (ILTV) SA-2 vaccine strain was determined. Several features were elucidated, including, 102 base pair (bp) inverted repeats separated by 750 bp of unique sequence which contains an NF-1 binding site indicating that the terminal may be a site for an origin of replication. Other direct repeats were also found in this region. To the right of the inverted repeat region, a 2130 bp region was found to contain small open reading frames (ORFs) of less than 100 aa. Another potential ORF was found to the right of the region containing the small ORFs which consisted of two 184 bp direct repeats inserted into the reading frame, which would truncate the putative product. Only one copy of this repeat was found in the corresponding homologue of the wild type strain SA-0. Six other ORFs were found, which shared little or no identity to homologues of other alphaherpesviruses, suggesting that these putative genes are unique to ILTV.

Base Sequence↗
PubMed1997

Cleaning of endodontic files, Part I: The effect of bioburden on the sterilization of endodontic files.

Ninety-two new endodontic files were randomly assigned to five groups with varying parameters of contamination, cleaning method, and sterilization (steam or chemical). Files were instrumented in bovine teeth to accumulate debris and a known contaminant, Bacillus stearothermophilus. Positive controls produced growth on both T-soy agar plates and in T-soy broth. Negative controls and experimental files (some with heavy debris) failed to produce growth. The results showed that there was no significant difference between contaminated files that were not cleaned before sterilization and contaminated files that were cleaned before sterilization. Bioburden present on endodontic files does not appear to affect the sterilization process.

Animals↗