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Biomedical subjects

L Johnson

Publications and source records attributed to L Johnson.

At least 217 records · Page 12Linked to original sources
PubMed1994

Exercise blood pressure response and skeletal muscle vasodilator capacity in normotensives with positive and negative family history of hypertension.

OBJECTIVE: To study exercise blood pressure response in association with exercising muscle maximal vasodilatory capacity in normotensives with a positive and negative family history of hypertension. SUBJECTS: Twenty-eight normotensive healthy subjects were recruited. Of these, two females and 13 males had a positive, and three females and 10 males had a negative, family history of hypertension. METHODS: Both groups of subjects rode a bicycle ergometer while systolic blood pressure, diastolic blood pressure and heart rate were measured at 30%, 60% and peak oxygen uptake rate. The vasodilatory capacity was examined in the lower leg by measuring the minimal vascular resistance during peak reactive hyperemia after 10 min arterial occlusion. RESULTS: Age, body weight, resting blood pressure, peak oxygen uptake rate and casual lower leg vascular resistance were not significantly different between the two groups of subjects. Significantly higher exercise systolic blood pressure (9%) and diastolic blood pressure (9%) were seen in the subjects with positive family history of hypertension compared with the subjects with negative family history of hypertension. Exercise heart rate was significantly higher in the subjects with negative than in those with positive family history of hypertension. The vascular resistance at peak vasodilation was 22% higher in the subjects with positive than in the subjects with negative family history of hypertension. CONCLUSIONS: This study demonstrates that the dynamic exercise blood pressure is exaggerated and skeletal muscle vasodilatory capacity is limited in normotensives with genetic risk of hypertension. This suggests that the higher pressor response to physical stress that is found in normotensives with a family history of hypertension may be attributed to the resistance vessels in the exercising muscle.

Adult↗
PubMed1994

Aortic sepsis from an appendiceal abscess.

A 75-year-old man with infection in a pre-existing abdominal aortic aneurysm secondary to an appendiceal abscess is described. A single similar case has been reported in the English literature. Appendicitis was diagnosed at exploration. In both cases, the appendix was located in a retroileal position in the retroperitoneum, thereby allowing tracking of the abscess to the aneurysm wall. Resection and extra-anatomic vascular reconstruction were curative.

Abscess↗
PubMed1994

Vulvar application of lidocaine for pain relief in spontaneous vaginal delivery.

OBJECTIVE: To evaluate the effect of topical perineal lidocaine on immediate postpartum perineal pain. METHODS: Two hundred three volunteers randomly received either 2% lidocaine jelly or chlorhexidine gluconate topically to the perineum during the second stage of labor in a double-blind study. A four-point analogue pain scale was used to rate perineal pain 30 minutes after delivery. Parametric data were evaluated with the unpaired Student t test. Nonparametric data were analyzed using Mann-Whitney, Pearson chi 2, and Mantel-haenzel tests, and forward stepwise logistic regression. RESULTS: Women receiving topical lidocaine reported less overall perceived pain (48%, P < .05) and less moderate to severe pain (52%, odds ratio 1.83, P < .04) at delivery than those receiving placebo (33 and 67%, respectively). The incidence of perineal lacerations was similar in the two groups. A logistic regression found topical lidocaine and multiparity as significant correlates of diminished peripartum pain (P < .007). CONCLUSIONS: Topical application of 2% lidocaine gel was associated with decreased pain perception in the immediate postpartum interval. If confirmed by other investigators, this technique may offer improved analgesia while minimizing the injection route with local analgesia.

Administration, Topical↗
PubMed1994

The legal implications of abuse of the unborn foetus.

This article looks at the use of psychoactive drugs by pregnant women and the effects of these on the foetus. Firstly it discusses the historical awareness of alcohol related birth defects, and then the symptoms of foetal alcohol syndrome. There is also the condition known as foetal alcohol effects--a milder version of foetal alcohol syndrome--exhibited by children of alcohol abusing mothers. Secondly, various drugs, both legal and illegal, over the counter and prescription drugs, and their effects on the foetus are examined. Thirdly, the moral, ethical and legal problems facing the health care worker when dealing with a pregnant women who will not or cannot stop using a potentially harmful chemical, are probed in terms of the South African Child Care Act 74 of 1983. Finally a plea is made for more research in this area, and also that coercive treatment and commital procedures should only be applied when all other methods for treatment have failed.

Alcoholism↗
PubMed1994

Outcomes analysis in spinal research. How clinical research differs from outcomes analysis.

This article discusses the outcomes research movement and makes a distinction between clinical research that includes measures of function and quality of life as variables, and outcomes measurement for operational purposes such as quality assurance and reporting to insurers and regulatory agencies. Suggestions are made about how to begin outcomes data collection in an orthopedic clinic setting and how to select which patient outcomes may be most relevant to the assessment of treatment for spinal deformities.

Humans↗
PubMed1993

Analysis of a transfer region from the staphylococcal conjugative plasmid pSK41.

The nucleotide sequence of a 14.4-kb region (tra) associated with DNA transfer of the staphylococcal conjugative plasmid, pSK41, has been determined. Analysis of the sequence revealed the presence of 15 genes potentially involved in the conjugative process. Polypeptide products likely to correspond to ten of these genes have been identified, of which one was found to be a lipoprotein. Comparison of the deduced tra products to the protein databases revealed several interesting similarities, one of which suggests an evolutionary link between this Gram+ bacterial conjugation system and DNA transfer systems of Gram- bacteria, such as Escherichia coli and Agrobacterium tumefaciens. The nt sequence also provided an insight into the transcriptional organisation and regulation of the region.

Amino Acid Sequence↗
PubMed1993

The serum response element can mediate induction of c-fos by growth hormone.

The c-fos protooncogene is transcriptionally activated by a wide variety of agents including serum, growth factors, and phorbol esters. This induction is rapid and transient and is mediated through a number of identified promoter elements. Growth hormone (GH) is also known to induce transcription of c-fos in a variety of cell types including NIH 3T3 fibroblasts and 3T3-F442A preadipocytes. To identify DNA sequences in the c-fos gene regulated by GH, this study sought to determine whether induction of c-fos by GH involves previously identified c-fos promoter elements. A plasmid containing a growth factor-sensitive fragment of the upstream region of the c-fos promoter from -361 to -264 bp was tested for GH sensitivity. The fragment was cloned upstream of a human c-fos reporter [designated FOS by Human Gene Mapping 11 (1991)], which included basal promoter elements. In transiently transfected mouse NIH 3T3 fibroblasts, the promoter fragment conferred GH sensitivity on the human c-fos reporter. To identify a specific GH-sensitive DNA sequence in this promoter, a serum response element (SRE)-reporter plasmid was tested and found to be stimulated by GH. GH was effective in inducing expression through the SRE over a range of physiological GH concentrations. Since GH was recently found to synergize with serum factors in inducing c-fos transcription, the effect of GH and serum on SRE function was examined for insight into the mechanism for such synergism. The combined effect of GH and serum to induce reporter expression through the SRE was greater than the added effects of GH and serum, indicating that the synergism between GH and serum in inducing c-fos involves the SRE sequence. These studies identify the SRE as one specific DNA sequence in the c-fos promoter functionally regulated by GH. It is notable that GH is effective at physiological concentrations. Furthermore, synergism in c-fos induction between GH and serum factors is evident through the SRE.

3T3 Cells↗
PubMed1993

A pilot Swedish twin study of affective illness, including hospital- and population-ascertained subsamples.

OBJECTIVE: We sought to compare the probandwise concordance rate (PRC) for affective illness (AI) in monozygotic (MZ) and dizygotic (DZ) twins in samples ascertained through psychiatric hospitalization vs samples from the general population. METHODS: Twins were ascertained through psychiatric hospitalization for AI from the Swedish Psychiatric Twin Registry or as a matched sample from the population-based Swedish Twin Registry. Lifetime diagnoses were based on a mailed questionnaire containing, in self-report format, DSM-III-R criteria for mania and major depression. Returned questionnaires were obtained from 1484 individuals and both members of 486 pairs, of whom 154 were classified as MZ, 326 as DZ, and six of unknown zygosity. RESULTS: No evidence was found for violations of the equal environment assumption. Using either a narrow or broad diagnostic approach, the risk for AI in cotwins of proband twins was independent of the gender, polarity (ie, unipolar vs bipolar) and mode of ascertainment of the affected proband (ie, via hospitalization vs from the general population). Combining both subsamples, PRC for total AI using narrow diagnostic criteria was 48.2% in MZ and 23.4% in DZ twins. Using broad diagnostic criteria, the parallel figures were 69.7% and 34.9%. The risk for bipolar illness was substantially increased in the cotwins of probands with bipolar AI. CONCLUSIONS: Genetic factors play a major role in the etiology of AI in Sweden, as assessed by self-report questionnaire. Heritable factors appear to be equally important in AI as ascertained in clinical and epidemiological samples.

Bipolar Disorder↗
PubMed1993

Architectural arrangement of stages of the spermatogenic cycle within human seminiferous tubules is related to efficiency of spermatogenesis.

Stages of the spermatogenic cycle in human seminiferous tubules were evaluated in men with varied efficiencies of spermatogenesis to determine if the architectural arrangement of stages or the atypical cell types contributed to variation in sperm production rates. Testes were selected from men with low, intermediate, and high daily sperm production per g parenchyma (DSP/g). Round tubular cross sections were photographed by bright-field microscopy. Stages were identified for each cross section by two observers and the number of stages represented in each cross section was recorded. Number of stages per cross section in men with low efficiency of spermatogenesis were significantly (P < 0.05) fewer than men with intermediate and high efficiency of spermatogenesis. Further, the percentage of stages with atypical cell types in men with high DSP/g was significantly (P < 0.05) higher than men with low DSP/g. There was a significant relationship (P < 0.01) between the percentages of stages with atypical cell types per stage and number of stages per cross section. The atypical cell types appear to result from high density of stages per cross section in men with high DSP/g. There was no significant difference observed between groups for tubular volume, diameter, length, volume density, and volume density of seminiferous epithelium. However, a significant (P < 0.05) positive correlation between percent seminiferous epithelium per testis with DSP/g or with the number of stages per cross section was found.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1993

Bone metabolism in children with asthma treated with inhaled beclomethasone dipropionate.

Previous studies have shown that inhaled corticosteroids can affect bone metabolism in adults. A study to assess the effect of inhaled beclomethasone, 300 to 800 micrograms/day for at least 6 months (mean 25 months), was therefore undertaken in children. In part 1 of the study, 18 children with asthma, aged 4 to 17 years (mean 10.1 years), were compared with an age- and sex-matched group of children with asthma not treated with corticosteroids. In part 2, eight more pairs were compared. Comparisons were also made with 61 healthy children. Bone mineral density measured by radiographic absorptiometry, and bone mineral content measured by single-photon absorptiometry and by dual-energy x-ray absorptiometry, showed no significant differences. Serum levels of calcium, magnesium, zinc, total alkaline phosphatase, bone specific alkaline phosphatase, parathyroid hormone, 25-hydroxyvitamin D, and 1,25-dihydroxyvitamin D also showed no differences. The activity of tartrate-resistant acid phosphatase, a marker of bone resorption, was significantly lower in the beclomethasone group than in both the asthma control and the normal control groups, but urine calcium excretion did not differ. Patients with asthma had lower serum osteocalcin and higher serum copper levels than control subjects without asthma, but treatment with beclomethasone did not affect these values. We conclude that inhaled beclomethasone (up to 800 micrograms/day) does not reduce bone mineralization or increase bone resorption. Effects on bone formation were difficult to assess because asthma per se caused a significant reduction in osteocalcin, a sensitive marker of bone formation.

Acid Phosphatase↗
PubMed1993

Immediate electronystagmography in the diagnosis of the dizzy patient.

STUDY OBJECTIVES: To determine whether the results of electronystagmography (ENG) testing improve an emergency physician's diagnosis of dizziness. DESIGN: Prospective, one-year. SETTING: University and three community hospital emergency departments. TYPE OF PARTICIPANTS: Ninety-three consecutive patients presenting with dizziness. INTERVENTIONS: ED impression was recorded after complete ED evaluation. An ENG was performed within one hour by an audiologist, who gave a reading of "central," "peripheral," or "normal." The result was given to the emergency physician, who was invited to revise his or her impression (the "ED impression after ENG result"). Final diagnosis was based on the ED impression and by contact with the patient's physician(s) as well as the patient by telephone after one and four weeks. Accuracy of ENG was assessed by comparing ENG reading with the final diagnosis using the chi(2) test. In addition, the contribution of ENG to ED diagnosis was assessed by comparing the accuracy of the ED impression after ENG reading with the ED impression alone using McNemar's test (hit versus no-hit). MEASUREMENTS AND MAIN RESULTS: Both ED impression and the ENG significantly correlated with the final diagnostic category (chi(2) = 104.9, P < .001; chi(2) = 70.79, P < .001, respectively). ENG correctly diagnosed nine of 11 patients with central dizziness. Of 23 patients with undetermined cause after ED evaluation, ENG correctly identified seven patients with peripheral dizziness and three with central dizziness. ED impression after ENG reading was more accurate than ED impression alone (chi(2) = 6.13, P < .05). CONCLUSION: Emergency physicians correctly categorized most dizzy patients, but audiologist performance and interpretation of an ENG significantly improved this categorization. ENG may have the potential to identify clinically unsuspected central dizziness and to categorize dizziness of "unknown" cause. Further study is needed to determine whether ENG could be performed by modifying certain types of heart monitors available in the ED.

Audiology↗
PubMed1993

Mycoplasma-like organism induced murine cardiac microvasculopathy. A transmission electron microscopic study.

Mycoplasma-Like Organisms [MLO] are intracellular cell wall deficient bacteria that cause ocular chronic vasculitis in man and chronic vascular disease in plants. Since MLO do not grow in culture, diagnosis of MLO-induced disease requires identification of the organisms by electron microscopy. Ultrastructurally, MLO appear as pleomorphic tubulo-spherical and filamentous organisms. In human ocular disease MLO have been detected in parasitised leucocytes and retinal pigment epithelial cells. We have previously reported the results of injecting MLO infected human vitreous into mouse eyelids. Two thirds of the mice developed chronic disease at the inoculation site, but, more importantly, the mice also developed lethal systemic MLO disease. Carditis with histologic features similar to those of various types of human carditis occurred in 18% of the mice. This report describes the ultrastructural features of the cardiac microvascular MLO disease in those 18 mice that died of carditis after inoculation with human MLO-infected vitreous. MLO were identified in leucocytes and endothelial cells of the murine vascular lesions. The vascular lesions were characterized by destruction of vessel walls as well as proliferation of endothelial cells. Electron dense deposits were seen in basement membranes and pericytial tissues. Similar features have been described in other bacterial vascular infections and in human idiopathic carditis. We suggest that MLO could be a cause of human cardiovascular disease and should be looked for in such cases.

Animals↗
PubMed1993

Characterization of macrophage sensitivity and resistance to anthrax lethal toxin.

Anthrax lethal toxin, which consists of two proteins, protective antigen and lethal factor, is cytolytic for macrophages. Macrophages from different mouse strains were found to vary in their sensitivities to toxin. C3H mouse macrophages lysed by lethal factor concentrations of 0.001 micrograms/ml were 100,000 times more sensitive than those from resistant A/J mice. We analyzed various stages of the intoxication process to determine the basis for this resistance. Direct binding studies with radioiodinated protective antigen revealed that the affinity (Kd, approximately 0.5 nM) and number of receptors per cell (25,000 to 33,000) were the same in sensitive and resistant cells. Proteolytic activation of protective antigen by a cell surface protease and subsequent binding of lethal factor were also the same in both sensitive and resistant macrophages. Resistant A/J macrophages were not cross-resistant to other toxins and a virus which, like lethal toxin, require vesicular acidification for activity, implying that resistance is not due to a defect in vesicular acidification. When introduced into the cytosol by osmotic lysis of pinosomes, lethal factor in the absence of protective antigen was cytolytic for the sensitive macrophages while resistant cells were unaffected. Thus, lethal factor by itself possesses the toxic activity of lethal toxin. These results suggest that macrophage resistance is due to a defect at a stage occurring after toxin internalization. A/J macrophages may lack the putative lethal factor target in the cytosol or be defective in the further processing or activation of lethal factor in the cytosol or in endocytic vesicles.

Animals↗
PubMed1993

Short latency vestibular evoked potentials.

Auditory responses, including the well-characterized auditory brainstem response, have been used extensively in clinical investigations. Evoked responses have not been adequately developed to investigate the vestibular system. The purpose of this study is to describe a new method for the evaluation of short-latency vestibular evoked potentials in human subjects. Standard ABR equipment is used, with a customized solid-state modification of the triggering mechanism. Signal averaging is used to record responses to multiple linear decelerations. Results indicate the presence of a short-latency wave, which is absent in vestibular-deficient subjects. The literature is reviewed and illustrative cases are presented. We believe vestibular evoked potentials are a promising new modality in investigation of vestibular physiology.

Evoked Potentials, Auditory↗
PubMed1993

Single daily ceftriaxone and tobramycin in the empirical management of febrile neutropenic patients: a randomised trial.

A single-institution, randomised pilot trial was conducted to compare the clinical efficacy, microbiological efficacy and possible toxicity of empirical single daily antibiotic administration in febrile neutropenic patients with haematologic disorders (absolute neutrophil count < 1 x 10(9)/l). Upon the development of signs of sepsis, patients received either single daily dose tobramycin (5 mg/kg per day) plus ceftriaxone (2 g/day) (C + T, n = 47) or tobramycin (1.5 mg/kg, every 8 h) plus azlocillin (4 g, every 6 h) (A + T, n = 45). In addition, flucloxacillin (1-2 g, every 4 h) could be added if there was clinical suspicion of staphylococcal infection (17 in each arm). Analysis was performed for the whole group and for the subset which did not receive flucloxacillin. When evaluated at 96 h, 62% of patients randomised to C + T and 67% randomised to A + T had responded (95% confidence interval (CI) for the difference in rates, -25% to +15%). Ninety-six hour response rates for those who did not receive flucloxacillin were 73% and 78%, respectively (95% CI, -17% to +27%). Overall, 42 (89%) and 41 (91%) patients, respectively, eventually became afebrile (95% CI, -14 to 10%) and there was no evidence of altered renal function or electrolyte imbalance in patients randomised to single daily antibiotic therapy compared with the conventional (multi-daily dose) arm. Within 10 days of antibiotic commencement there was 1 death in the C + T arm and 4 deaths in the A + T arm, although overall there were 4 deaths in each arm. Our results suggest that single daily empirical antibiotic therapy with tobramycin and ceftriaxone is efficacious and is not associated with an increased incidence of renal dysfunction or electrolyte imbalance compared with conventional administration schedules of azlocillin plus tobramycin. Single daily therapy has the potential to lead to savings in nursing-staff time and materials and may well contribute to an improved quality of life for febrile neutropenic patients.

Adolescent↗
PubMed1993

[Problems found in the isolation of mycelial fungi (Fusarium solani) from blood culture (Bacter NR-860)].

BACKGROUND: F. solani fungemia is unusual. Patients at risk are immunosuppressed, have underlying malignancy or severe debilitating diseases. METHODS: We report two cases of F. solani fungemia in two non neutropenic patients who had been treated with wide-spectrum antibiotics an/or systemic corticosteroids, parenteral nutrition and intravenous lines. Bactec NR-860 (Becton-Dickinson) system was used, and growth was detected in aerobic conditions (between 3-7 days of incubation). RESULTS: Removal of the catheters with or without i.v. amphotericin B were used successfully. CONCLUSION: The spectrum of Fusarium sp. fungemia is discussed. Current available antifungal therapy is also reviewed.

Aged↗
PubMed1993

Use of cytosine arabinoside and total body irradiation as conditioning for allogeneic marrow transplantation in patients with acute lymphoblastic leukemia: a multicenter survey.

We report the experience of 14 centers which have used the combination of cytosine arabinoside (ara-C; 24-36 g/m2) and total body irradiation (TBI) to prepare 213 patients with acute lymphoblastic leukemia (ALL) for allogeneic BMT. The overall 3-year disease-free survival (DFS) probability is 38% (95% CI: 31-45%); 75 patients died of complications and 51 relapsed. Multivariate analysis identified three factors independently associated with outcome: age, remission/relapse status and patient-donor relationship. The 3-year DFS probability is 52% (41-63%) for the 106 patients aged 0-11 and 25% (16-33%) for the 104 aged 11+ years; the DFS probability was 54% (34-74%), 41% (32-49%) and 19% (5-33%) for those in first remission, later remissions and relapse respectively. Older patients suffered both more toxic deaths and more relapses than young ones. No other covariate was found to predict for outcome. The results using ara-C-TBI are similar to those achieved using cyclophosphamide plus TBI to prepare ALL patients for BMT, perhaps because a seemingly lower relapse rate is offset by more toxic deaths particularly in older patients. Therapeutic trials should focus on reducing toxicity while maximizing antileukemic efficacy, and should stratify for patient and disease-related factors.

Adolescent↗