Search PubMed⌕ Search

Biomedical subjects

N Johnson

Publications and source records attributed to N Johnson.

At least 271 records · Page 15Linked to original sources
PubMed1987

Treatment of advanced and inaccessible sarcomas with continuous intra-arterial chemotherapy prior to definitive surgery or radiotherapy--a possible alternative to amputation or disabling radical surgery.

Four patients with advanced and inaccessible soft tissue sarcomas were treated with a regimen of intra-arterial chemotherapy followed by radiotherapy and/or surgical excision. Two of the patients had advanced sarcomas in the buttock and thigh regions which would otherwise have required hindquarter amputation in one case or disarticulation of the hip in the other case. These sarcomas responded significantly to intra-arterial chemotherapy to the extent that subsequent local surgery was effective in eradicating the residual tumours. No viable tumour cells were found in the resected specimens. In both patients amputation was avoided and local tumour eradication was achieved. In the other two patients, advanced and non-resectable sarcomas in the head were first treated with a similar regimen of intra-arterial chemotherapy. In both cases the tumours regressed in size prior to administration of local radiotherapy. After completion of chemotherapy and radiotherapy no viable tumour cells were detected in either lesion. In one case (originally a very extensive sarcoma of the jaw in a 5 year old child) a residual lump was resected but no viable tumour was detected in the resected specimen. These four patients represent our total experience with this plan of management. All responded well and there has been no evidence of local disease recurrence in any of the four patients. One patient (Case 2) did develop pulmonary and bone metastases from which she died 2 years later but the other three patients remain well with no evidence of residual disease, 11 years, 4 years and 20 months after presentation.

Adult↗
PubMed1987

Preliminary findings suggesting cyclic changes in visual contrast sensitivity during the menstrual cycle.

Visual contrast thresholds to both stationary and moving gratings of three spatial frequencies (2, 4, and 16 cyc/deg) were measured over a 32-day period in two women displaying normal menstrual cycles and in two noncycling control subjects. The time-series data of each subject in each condition were Fourier analyzed and the resulting amplitude spectra showed differences between the two sets of subjects. The spectra of the control subjects were relatively flat, whereas those of the experimental subjects showed a number of peaks at several harmonics (periods). Conservative significance tests suggested that the peaks in the spectra of the cycling women were larger than might be expected by chance. The data also suggested that changes in sensitivity were greatest for 4-cyc/deg gratings, those nearest the peak of the normal contrast sensitivity function.

Adult↗
PubMed1987

Cumulative pregnancy rates for donor insemination according to ovulatory function and tubal status.

From our study of 234 cases of AID with fresh semen, we conclude the following: (1) women who do not have other infertility problems, such as ovulatory dysfunction or evidence of tubal disease, have approximately a 90% chance of pregnancy if they stay in the program for up to 12 cycles; (2) with even greater persistence (i.e., greater than 12 cycles), it is predicted that virtually 100% of these women would conceive, but this conclusion is based on extrapolated data and therefore must be interpreted with caution; (3) women with ovulatory dysfunction who are treated with CC during their AID cycles ultimately achieve the same likelihood of pregnancy as women with normal ovulatory function, but at a slower rate; and (4) women with one patent tube (possibly a marker for generalized tubal damage) have a poorer outcome from AID than those with bilaterally patent tubes, from the standpoint of both the ultimate likelihood of pregnancy and the pregnancy rate per cycle.

Adult↗
PubMed1986

"Risk" factors affecting readmission of the elderly into the health care system.

One hundred one patients, 70 years and older, who were discharged to the community from an acute-care hospital were followed for 1 year to isolate risk factors affecting the probability of readmission. A total of five interviews were conducted with each patient. Postdischarge outcome at any point in time was defined as either readmission to a health care institution or continuous survival in the community. At 1 year, 47 individuals had experienced at least one unplanned readmission. Logistic regressions were used to study risk factors influencing the probability of readmission at 6 weeks, 6 months, and 1 year after release from the hospital. In the short run, sex, being widowed, a weighted severity-of-illness factor, and life satisfaction were significant; previous hospitalization and admission and discharge location were additional variables significant in the long run. An explanation is offered for why some risk factors useful in postadmission studies do not function as well as risk factors in post-discharge studies.

Age Factors↗
PubMed1986

Characteristics of initiation and termination of catecholamine-induced triggered activity in atrial fibers of the coronary sinus.

We studied epinephrine-induced delayed afterdepolarizations and triggered activity in atrial fibers from the canine coronary sinus to determine whether their responses to cardiac pacing would aid in formulating a uniform set of guidelines for differentiating this triggered activity from other arrhythmogenic mechanisms. We used standard microelectrode techniques and compared the delayed afterdepolarizations and triggered activity with those occurring in ouabain-superfused Purkinje fibers. Like Purkinje fibers, the frequency of triggering in the coronary sinus and the coupling interval of the first triggered beat were related directly to the basic drive cycle length, and the delayed afterdepolarization amplitude and frequency of triggering were related to the coupling interval of premature stimuli (S2). However, unlike Purkinje fibers, the coupling interval of the delayed afterdepolarization and of the first triggered beat were independent of the S2. Once initiated, triggered activity in the coronary sinus followed one of four rhythm patterns: in all four, the minimum and equilibrium cycle lengths were independent of the initiating cycle length. Triggered activity was terminated by overdrive and S2 pacing, especially by long episodes of overdrive at short cycle length. The first escape beat after overdrive was linearly related to the overdrive cycle length, resulting in overdrive acceleration. The return cycle length after S2 was linearly related to the S2 coupling interval. Because delayed afterdepolarizations and triggered activity in the coronary sinus respond differently to pacing from those in ouabain-superfused Purkinje fibers, triggered activity in general may not be identified by a uniform set of guidelines.

Action Potentials↗
PubMed1986

The association of dyslipoproteinemia with symptoms and signs of peripheral arterial disease. The Lipid Research Clinics Program Prevalence Study.

Intermittent claudication, leg pain during a graded exercise test (GXT), and resting systolic pressures in the upper and lower extremities were recorded as indicators of peripheral arterial disease at visit 2 of the Lipid Research Clinics (LRC) Prevalence Study. Systolic pressures of the upper and lower extremities were measured in a subsample of participants. We compared lipid levels of persons with and without claudication and with or without GXT-induced leg pain. We also compared lipid levels between groups with high and low arm:ankle systolic blood pressure ratios. Twenty-one (1.0%) men, 10 (1.0%) female nonusers and six (1.0%) female users of gonadal hormones had intermittent claudication determined by standardized questionnaire. Men with claudication had lower high-density lipoprotein (HDL)-cholesterol (35.6 vs 46.4 mg/dl), and their mean triglyceride level and cigarette consumption were higher and regular exercise less frequent. Men with type IIb dyslipoproteinemia were more likely to report claudication. One hundred sixty-nine (4.0%) men, 101 (3.8%) female nonusers, and 47 (4.1%) female users of hormones stopped the GXT because of leg pain. Mean HDL-cholesterol levels were lower for those with GXT-induced leg pain in all three sex-hormone usage groups (42.0 vs 46.9, p less than .001; 53.9 vs 59.4, p less than .001; 65.3 vs 67.2, p = NS) and mean low-density lipoprotein cholesterol levels were higher in those with leg pain on GXT in two of three groups (146.4 vs 146.2, p = NS; 155.7 vs 144.6, p less than .01; 144.4 vs 133.5, p less than .05).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1986

Alterations in clinical chemistry levels associated with the dyslipoproteinemias. The Lipid Research Clinics Program Prevalence Study.

Mean blood levels of eight components of clinical chemistry and the proportion of participants with abnormal chemistry values were calculated for persons with six dyslipoproteinemias (DLPs) and compared with findings from normolipidemic participants in 10 defined North American Lipid Research Clinics Program study populations. Most of the significant differences in mean chemistry levels were in persons with type IIB and IV DLP, and were characterized by higher mean levels of serum alkaline phosphatase, glucose, SGOT, and uric acid, and by lower mean levels of total bilirubin and thyroxine. Similarly, persons with type IIB and IV DLP were more likely to have significantly increased percentages of abnormal clinical chemistry values than were normolipidemics, but for a given chemistry this was rarely over 10% to 15% higher. With the exception of some participants with types IIB and IV DLP, the DLPs detected in these study populations were not associated with a substantial prevalence of abnormal clinical chemistry values and, by inference, were not frequently associated with the diseases or metabolic abnormalities for which these chemical abnormalities are indicators.

Adult↗
PubMed1985

Pseudomalignant osseous tumor of the temporalis muscle.

A case is presented of a 10-year-old girl who had a benign osseous tumor of the temporalis muscle. The tumor appeared to be a variant of the so-called pseudomalignant osseous tumor of the soft tissues and could readily be distinguished from both osteogenic sarcoma and myositis ossificans.

Child↗
PubMed1985

Establishment and characterisation of cell lines from patients with lung cancer (predominantly small cell carcinoma).

Tissue samples from 59 patients with lung cancer have been used to establish cell lines in culture. The primary diagnosis was small cell carcinoma in all except four. Most of the samples were of bone marrow but pleural effusions, lymph node biopsies and skin metastases were also included. The samples were usually split between HITES serum-free medium and HITES plus 2.5% foetal calf serum. A total of 19 cell lines were established and characterised. One line is large cell anaplastic lung carcinoma, four are B-lymphoblastoid and fourteen are small cell lung cancer. Considerable heterogeneity in gross morphology, neuroendocrine differentiation (by electron microscopy) and content of the enzyme L-dopa decarboxylase was seen. The use of HITES plus 2.5% foetal calf serum resulted in better establishment of cultures than did serum-free HITES.

Bone Marrow↗
PubMed1985

Analysis of asbestos fibers and asbestos bodies in tissue samples from human lung. An international interlaboratory trial.

In order to compare methods of counting asbestos fibers in lung tissue, seven laboratories participated in an interlaboratory trial in which tissue samples from five human lungs were analyzed. In some laboratories, fiber concentrations were assessed with the light microscope and, in others, with either scanning or transmission electron microscopes. Within each laboratory the ranking of the results was similar, but there were marked differences in the absolute values obtained by the different laboratories. It is concluded that the laboratories participating in this trial appear to produce internally consistent results, but there is difficulty in directly comparing results from one laboratory to the next.

Aged↗
PubMed1985

Irreversible opiate agonists and antagonists. III. Phenylhydrazone derivatives of naloxone and oxymorphone.

In view of previous studies indicating that the irreversible properties of opiate azines such as naloxonazine are not due to a bivalent mechanism, we have synthesized a series of opiate hydrazones. In standard competition assays which measure both reversible and irreversible inhibition of binding, the hydrazone derivatives lowered radiolabeled opioid binding almost as well as naloxone and oxymorphone. However, the phenylhydrazone derivatives produced a profound wash-resistant inhibition of binding. The similar potencies of the methylhydrazine and phenylhydrazine derivatives in standard competition studies contrasted significantly with their effectiveness in eliciting wash-resistant inhibition of binding, suggesting the importance of the phenyl group in the production of wash-resistant inhibition. The p-nitrophenyl hydrazones were the most effective wash-irreversible inhibitors. Although oxymorphonazine does not irreversibly inhibit radiolabeled opioid binding as effectively as naloxonazine or naltrexonazine, the oxymorphone phenylhydrazones were as potent as their corresponding naloxone compounds. Incubation of [3H]naloxone-p-nitrophenylhydrazone with albumin demonstrated significant incorporation of radiolabel into the protein after sodium dodecylsulfate gel electrophoresis. This suggests that the phenylhydrazones have significant reactivities toward proteins and might produce their irreversible actions through covalent interactions.

Albumins↗
PubMed1984

Interaction of two phencyclidine opiate-like derivatives with 3H-opioid binding sites.

Small modifications of the basic structure of phencyclidine have produced compounds with potent opioid analgesic actions. Detailed competition studies show that two of these phencyclidine derivatives, the 3'-hydroxy and the 4-phenyl-4-hydroxy analogs, displace 3H-opioid binding in a multiphasic manner. Approximately 25% of the total specific binding of all the radiolabeled opioids is displaced by low concentrations of the derivatives while the remainder of the binding is far less sensitive. The inclusion of these derivatives in saturation studies with [3H]dihydromorphine indicate that both compounds interact with highest affinity with mu1 sites. Furthermore, the prior in vivo administration of naloxonazine 24 h earlier reduces the analgesic potency of the 4-phenyl-4-hydroxy compound by 63% supporting a mu1 mechanism of action.

Analgesics↗
PubMed1984

Tissue glutathione as a cyst(e)ine reservoir during cystine depletion in growing rats.

Previous data suggest that liver glutathione (GSH) serves as a cyst(e)ine reservoir in rats starved or fed cyst(e)ine-deficient diets. In the present study we investigated whether extrahepatic tissue GSH concentrations also decreased during cystine (Cys-Cys) depletion and whether excess dietary cystine increased tissue GSH and cysteine (Cys) concentrations. Five groups of growing rats (80-100 g) were fed diets containing crystalline L-amino acids differing in methionine (Met) and cystine (Cys-Cys) content for 15 days. All diets were isonitrogenous (1.3 g/100 g diet) and provided the minimum Met (0.17%) required by growing rats. Diet 1 provided 0.17% Met and 0% Cys-Cys, diet 2 (the recommended diet) provided 0.17% Met and 0.26% Cys-Cys, diet 3 provided 0.50% Met and 0% Cys-Cys, diet 4 provided 0.17% Met and 0.39% Cys-Cys and diet 5 provided 0.17% Met and 0.52% Cys-Cys. Diets 2 and 3 were isosulfurous at 3.3 mmol/100 g diet. Diets 4 and 5 provided 50 and 100%, respectively, more Cys-Cys than required when 0.17% Met was present. Animals fed diet 1 (Cys-Cys depletion) had significantly decreased (P less than 0.05) liver, muscle, spleen, heart and thymus GSH concentrations, whereas brain, small intestine and erythrocyte GSH concentrations remained unchanged. Although brain and small intestine Cys concentrations were not affected by Cys-Cys depletion, spleen, heart and liver Cys concentrations decreased significantly (P less than 0.05). Feeding Cys-Cys above the requirement level did not increase GSH and Cys concentrations of any tissue except liver where Cys levels were elevated. The data indicate that liver, muscle, spleen, heart and thymus GSH serve as Cys reservoirs during Cys-Cys depletion.

Amino Acids↗