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Biomedical subjects

M Larson

Publications and source records attributed to M Larson.

At least 55 records · Page 3Linked to original sources
PubMed1991

The influence of tonsillar obstruction and tonsillectomy on facial growth and dental arch morphology.

Children, who were tonsillectomized because of sleep apnea were examined with respect to facial growth and dental arch morphology. Dental casts and lateral roentgencephalograms were analysed before surgery and two years after tonsillectomy. The findings were compared to data from children without tonsillary obstruction. A higher proportion of malocclusion than normal, especially open bite and crossbite, was noticed before surgery. Two years after surgery, 77% of the open bites were normalised and 50-65% of the buccal and anterior crossbites. The best results were seen in children operated before the age of 6.

Adolescent↗
PubMed1988

Immunogenetic and racial determinants of gold toxicity in rheumatoid arthritis.

Typing for antigens HLA-A,B,C and DR was performed on 165 rheumatoid arthritis patients (14 black, 151 white) who had received gold therapy to determine the relationship between HLA antigens and gold dermatitis, stomatitis, thrombocytopenia, and proteinuria. Dermatitis and stomatitis occurred in both black and white patients. Thrombocytopenia and proteinuria occurred only among the white patients studied. The absence of thrombocytopenia and proteinuria among the black patients was not statistically significant. Antigen HLA-DR7 was uncommon among black and white subjects with dermatitis (0 of 6 blacks, 4 of 48 whites), but this decrease in frequency was not statistically significant. Antigen HLA-DR3 was an important risk factor for thrombocytopenia (relative risk = 11.8, P = .0043) and proteinuria (RR = 5.8, P = .032). These results are consistent with previous studies of HLA-DR3 and gold toxicity. The only black patient with stomatitis possessed the A1B8DR3 phenotype. Future studies should examine whether the same HLA antigen confers risk of different gold toxicities in different racial groups, and whether there are HLA antigens that provide a protective effect.

Arthritis, Rheumatoid↗
PubMed1988

Diagnostic value of the history and examination in giant cell arteritis: a clinical pathological study of 81 temporal artery biopsies.

To determine the value of the history and examination in predicting a temporal artery biopsy result, 81 temporal artery biopsies between 1974-1980 were studied. Each biopsy was scored blindly and independently by 2 pathologists and correlated with clinical data and the indications for biopsy at the time of the biopsy. Thirteen biopsies had giant cells and were considered positive, 8 had mononuclear inflammatory cells in the wall (7 cases) or healed arteritis (1 case) and were considered probable, and 60 were negative. In patients with an elevated sedimentation rate, the presence of a sign (tenderness or abnormal temporal artery), or a symptom (visual change or headache) predicted 18 of 21 (86%) positive-probable biopsies, but misclassified 32 of 60 negative biopsies. Attempts to derive a clinical decision rule with improved specificity resulted in unacceptably low sensitivity (missing 5 of 21 positive-probable biopsies). A minimum 5-year followup showed that those patients treated with steroids had a 6-fold increase in fractures and a 4-fold increase in cataracts.

Aged↗
PubMed1987

Femoral expansion in total hip arthroplasty.

With increasing age, the femoral medullary canal expands and cortical thickness decreases. Examination of the radiographs of 22 hips that had undergone total hip arthroplasty revealed that at a mean interval of 11.5 years the medullary canal had expanded at an average rate of +0.328 mm/year (P less than .0001). There was a concomitant mean cortical atrophy of -0.155 mm/year (P = .0006). These rates of expansion are similar to those observed in natural aging. The presence of a femoral prosthesis is associated with temporal changes in femoral geometry similar in magnitude to those occurring in the natural femur. Because of the fundamental changes in load transmission caused by the presence of a femoral prosthesis, these geometric changes may be in part secondary to the bone's adaptation to altered load transmission, as well as to natural aging phenomena. Recognition of the pattern of natural femoral expansion suggests certain strategies for design criteria that seek to maximize fit.

Adult↗
PubMed1987

Functional characteristics of peritubular capillary membrane in rat kidney.

The permeability characteristics of the peritubular capillary membrane in the rat kidney were investigated on the basis of the transport of hippuran, inulin, myoglobin, horseradish peroxidase, albumin, and gamma-globulin from peritubular capillary blood to renal hilar lymph. Data obtained in a previous investigation on single-nephron plasma flow, filtration fraction, net driving force, and fluid reabsorption along the peritubular capillary were also used. The data were analyzed in a computer-based model taking into account the transport both by diffusion and by convection. The results show that the membrane contains a few large pores through which the plasma proteins leak out into the renal interstitium and a system of several smaller pores responsible for the fluid reabsorption. The mean equivalent radius of the large pores was estimated from the larger molecular probes to be approximately 180 A (range 150-225 A), and the corresponding total pore area over pore length was estimated at 3 X 10(-4) cm (range 6 X 10(-4) to 1 X 10(-4) cm). The small-pore system was analyzed from the transport of hippuran, inulin, and myoglobin and from fluid reabsorption and showed a pore radius of somewhat below 20 A and pore areas over pore length of 50 cm. Here, the fluid reabsorption and the transport of hippuran turned out to be a sensitive marker of the pore area and the transport of inulin and myoglobin of the pore radius.

Animals↗
PubMed1986

Auranofin therapy and quality of life in patients with rheumatoid arthritis. Results of a multicenter trial.

In a six-month, randomized, double-blind study at 14 centers, auranofin (3 mg twice daily) was compared with placebo in the treatment of patients with classic or definite rheumatoid arthritis. All patients had unremitting disease for at least the previous six months and at least three months of therapy with nonsteroidal anti-inflammatory drugs (NSAIDs). NSAIDs, oral steroids, and analgesics were allowed throughout the trial. Efficacy was analyzed in 154 patients who received auranofin and 149 who received placebo. To reflect an expanded view of outcome assessment, the measures used included some 20 nontraditional measures of functional performance, pain, global impression, and utility (worth or value) in addition to five standard clinical measures of rheumatoid synovitis (e.g., number of tender joints). The nontraditional measures were mainly in the form of structured questionnaires administered by trained interviewers. To minimize the statistical problem of multiple comparisons, most of the measures were grouped into four composites--clinical (standard measures), functional, global, and pain--and the treatment effect for each composite was tested at the 0.0125 level of significance. Auranofin was superior to placebo in the clinical (p = 0.003), functional (p = 0.001), and global (p = 0.007) composites and trended similarly in the pain composite (p = 0.021). Individual measures within the composites consistently favored auranofin. Other measures, not part of the composites, also favored auranofin, including a patient utility measure designed for this study, the PUMS (p = 0.002). Results confirm the hypothesis that the favorable effect of auranofin on clinical synovitis is accompanied by improvements across a range of outcomes relevant to the patient's quality of life.

Adult↗
PubMed1986

Carbonic anhydrase inhibition and cell volume regulation in Necturus gallbladder.

Gallbladder epithelial cells transport salt and water isotonically as the renal proximal tubule. The cells also have the property of regulating their cell volume in response to osmotic stress (Fisher et al. 1981, Persson & Spring 1982, Fisher & Spring 1984, Foskett & Spring 1985). The volume-regulating phenomenon is the result of a balance between cell uptake of salt and water at the luminal membrane and exit at the basolateral membrane. Different properties regarding volume regulatory increase and decrease have been found (Eriksson & Spring 1982 and Larson & Spring 1983). The present study links fluid transport and volume regulatory increase of the cell. First we concluded from histological techniques that carbonic anhydrase is present in the cell membrane or in the vicinity of the epithelial cells. Then we measured a decreased net fluid transport in the presence of increasing concentrations of the carbonic anhydrase inhibitor acetazolamide. We showed that the volume regulatory increase is substantially slowed down and that the steady-state volume of the cells changed when carbonic anhydrase was inhibited. Our conclusion is that the rate of CO2 hydration was a limiting step, at carbonic anhydrase inhibition, in both the net transfer of salt and water and also in the ability of the cells to efficiently regulate their volume.

Acetazolamide↗
PubMed1985

HLA gene frequencies in children and adults with systemic onset juvenile rheumatoid arthritis.

The HLA genetic region was studied in 51 patients with systemic onset juvenile rheumatoid arthritis: 35 with childhood onset and 16 with adult onset (adult Still's disease). HLA genotypes were established by including family members, 261 of whom were also typed in the study. The most marked difference between patients and controls involved the HLA-DR4 gene, which occurred with a frequency of 0.348 in the childhood onset patients and 0.170 in the controls (chi 2 = 8.97, P = 0.0028, adjusted P = 0.017). In contrast, the adult onset patients showed a marginal increase in HLA-DR7, but were similar to controls with respect to HLA-DR4. HLA-Bw35 was increased in children with systemic onset disease, in accordance with earlier findings. The results suggest that patients with systemic onset juvenile rheumatoid arthritis have complex HLA associations which are different in childhood onset and adult onset disease.

Adolescent↗
PubMed1985

Sex ratio and sibship size in juvenile rheumatoid arthritis kindreds.

In a study of sibship size and sex ratio in juvenile rheumatoid arthritis, the anticipated sex ratios, including a marked female predominance in early onset pauciarticular disease and in polyarticular disease, were found. The size of the sibship showed a progressive increase with increasing age of the proband at onset of disease. In addition, the sex ratios of the sibs deviated from expected, among families where the proband's disease was characterized as either early onset pauciarticular or polyarticular in its presentation.

Adolescent↗
PubMed1984

The psychosocial impact of systemic lupus erythematosus and rheumatoid arthritis.

Seventy-six ambulatory patients with systemic lupus erythematosus and a comparison group of 23 ambulatory patients with rheumatoid arthritis were given a structured interview and standard psychological tests, including the Minnesota Multiphasic Personality Inventory, to determine the psychosocial impact of the illness. Both groups had significantly elevated scores on 3 Minnesota Multiphasic Personality Inventory scales: Hypochondriasis, Depression, and Hysteria. Psychological difficulties are an integral part of systemic lupus erythematosus and are as common as most other manifestations. The implications for clinical practice are discussed.

Arthritis, Rheumatoid↗
PubMed1984

Costs and outcomes in rheumatoid arthritis and osteoarthritis.

A prospective descriptive study was done on the direct and indirect costs to ambulatory patients with rheumatoid arthritis and osteoarthritis, stratified at study entry by level of function. Measures of health status over a 1-year period were taken. On a yearly basis, in 1979 dollars, patients spent an average of $147 for arthritis medications, aids, and devices, and $207 for outpatient visits. A small number were hospitalized and incurred an average charge of $245, and an additional $84 for physician fees. In addition to direct monetary costs, patients averaged 6.8 days of restricted activity costs, patients averaged 6.8 days of restricted activity per month, in some cases so severe as to confine patients to bed for an average of 1.3 days per month. Among students and working patients, 2.5 work-days per month were lost due to arthritis, and 30% reported that they were unemployed or retired because of impaired health. Functional capacity and specific diagnosis on entry to the study were the most important determinants of arthritis-related expenditures. Both direct and indirect costs varied considerably from the observed average. Twenty percent of patients incurred no costs for arthritis-related purchases, 42+ had no costs for outpatient visits, and 93% had no inpatient costs. Yet for some patients, the financial burden was very high.

Arthritis, Rheumatoid↗
PubMed1984

Volume regulation by Necturus gallbladder: basolateral KCl exit.

Swelling of the epithelial cells of Necturus gallbladder caused by an 18% reduction in the osmolality of the mucosal bath is followed by rapid volume readjustment. This volume regulatory decrease requires Cl and is sensitive to the K and Cl gradients across the basolateral cell membrane. Volume regulatory decrease is not inhibited by amiloride, SITS, ouabain or bicarbonate removal. The process is blocked by bumetanide in the serosal bath. Measurement of the intracellular activities of K and Cl and the rate of volume regulation under five different experimental conditions showed that KCl exited from the cell across the basolateral membrane with a stoichiometry of 3 K to 2 Cl. This KCl exit process appears to be transiently activated following the reduction in osmolality of the mucosal perfusate.

4-Acetamido-4'-isothiocyanatostilbene-2,2'-disulfo↗
PubMed1984

Renal interstitial volume of the rat kidney.

The intravascular plasma volume and the interstitial volume of the rat kidney were determined by an indicator dilution method with a bolus injection of 125-I-labelled human serum albumin and 51-Cr-EDTA into the renal artery and subsequent recording of the indicator-dilution curves in the venous effluent, sampled at intervals of 0.33 s. The curves allowed determination of both the mean transit time of the two indicators and total renal plasma flow. The volumes of distribution were obtained by multiplying these two factors. Under control conditions the plasma volume was 93.0 +/- 11.2 microliters/100 g rat (mean +/- SE), which is 17.9% of the total kidney volume. The interstitial volume was 68.3 +/- 8.6 microliters/100 g, corresponding to 13.1% of the total kidney volume. During expansion with 0.15 M NaCl, 10% of body weight, the plasma and interstitial volumes were not significantly increased. The values for the two volumes were 101.6 +/- 9.7 and 72.8 +/- 6.8 microliters/100 g, respectively. The kidney weight showed, in contrast a clear increase from 539 to 670 mg/100 g, reflecting the expansion of the proximal and distal tubules due to the increased glomerular filtration rate. It is concluded that although the saline load produced a rise in the renal interstitial pressure, the expected expansion of the interstitium became small, due to the parallel expansion of both the vascular and tubular systems which compress the renal interstitium.

Animals↗
PubMed1984

Respiratory muscle training with the incentive spirometer resistive breathing device.

Utilizing the conceptual scheme of Kim, this study focused on the effect of inspiratory muscle training on the strength of the respiratory muscles, exercise performance, clinical manifestations, and activities of daily living. Unlike previous studies, inspiratory muscle training was performed by the use of an ISRBD that gave alinear inspiratory resistance of 50 cm H2O/L/sec at 1 L/sec flow. Subjects used an ISRBD twice a day for 15 minutes each day for 4 weeks. Strength of respiratory muscles as measured by PImax and sputum expectoration improved significantly (P less than 0.05) but there was no significant change in exercise performance (12-minute walk distance), other clinical signs and symptoms, or activities of daily living. Visual feedback given by the bellows of the ISRBD that inflated and deflated with inspiration and expiration apparently served as a positive reinforcer and motivator for most subjects. Daily logs of clinical signs and symptoms and activities of daily living, along with weekly telephone conferences with each subject, provided comprehensive data and may have contributed to the high compliance rate (98%) in this study.

Activities of Daily Living↗