Factors affecting primary care physician participation in Medicare

OBJECTIVES: This study investigates the levels of participation and the relative association of economic and noneconomic factors on primary care physician participation in the Medicare program. METHODS: Demographic information, participation in Medicare, and attitudes toward both the Medicare program and Medicare patients were collected in a written survey mailed to half the primary care physicians in Iowa. Ordinary least squares and logistic regression analyses were conducted to determine factors associated with the percentage of Medicare patients in a practice and the acceptance of all new Medicare patients, respectively. RESULTS: Two thirds of physicians were accepting all new Medicare patients, whereas 16% were accepting no new Medicare patients. Factors associated with having a higher percentage of Medicare patients in a practice were as follows: (1) a larger proportion of Medicare recipients in the county, (2) practice as a general internal medicine physician, (3) more years in practice at the current location, (4) greater enjoyment treating elderly patients, (5) less concern about having too many Medicare patients, and (6) a stronger belief that the Medicare program respects their professional judgment. Physicians less concerned about having too many Medicare patients in their practice and physicians in counties with a higher percentage of Medicare patients were significantly more likely to accept all new Medicare patients. CONCLUSIONS: These results suggest that as Medicare reforms are discussed, careful consideration of the impact of these reforms on noneconomic issues is important to ensure adequate physician participation and access for elderly patients through the Medicare program.     

A fetal sheep liver extract reverses age-related increments in spontaneous and induced cytokine production by indirect environmental effects

BALB/c, DBA/2 and C57BL/6 mice of different ages (ranging from 8 to 110 weeks of age) were used as spleen cell donors to assay cytokine production from ConA activated spleen and Peyer's Patch (PP) lymphocytes. As reported in an earlier publication, there was an age-related decline in IL-2 production in all strains, with a general increase in IL-4 and IL-10 production with age, this being particularly marked for PP cell preparations. Similar conclusions were reached from independent analysis of CD44hi and CD44lo cell populations in these groups (memory vs. naive cells, respectively). Interestingly, IL-6 production was dramatically increased (some 4-5-fold in the different strains) and significantly increased levels of IL-6 were detected in the serum of aged mice. A previously described sheep fetal liver extract was able to reverse, to varying degrees, these cytokine changes associated with aging. Interestingly, when cells from aged mice were adoptively transferred to lethally irradiated young (8 week) recipients, the cytokine production phenotype of cells harvested from recipient mice 3 weeks later was that of the aged donor, unless recipients were treated continually with extract. Treatment of the donor alone produced minimal changes in cytokine production 3 weeks following adoptive transfer. The effect of extract was reversed in treated aged mice by concomitant daily intravenous infusion of the competitive inhibitor of nitric oxide synthesis (NG-monomethyl-L-arginine (NMMA)), which also decreased the increased serum nitrate levels in mice treated with extract. Our data suggest an important role for reactive nitrogen products, themselves induced by fetal liver extract, in age-associated changes in cytokine production.     

Vegetational association of host-seeking adult blacklegged ticks, Ixodes scapularis Say (Acari: Ixodidae), on dairy farms in northwestern Wisconsin

Non-obese diabetic NOD/SCID mice have been used to grow human leukaemia as a systemic disease. The animals were inoculated with leukaemic cells obtained from a 36-year-old male with early B-cell precursor acute lymphoblastic leukaemia and on day 15 were given the first of three weekly injections of 1 mg/kg vincristine or equimolar liposomal vincristine. The development of leukaemia in the mice was monitored by taking weekly blood samples and measuring the cell content by flow cytometry. The median time to 50% human cells in the peripheral blood of mice treated with free vincristine was 41 d from the start of treatment compared with 49 d for mice treated with liposomal vincristine (P < 0.01). The median day of death for mice treated with free vincristine was 47 d from the start of treatment and 57 d for mice receiving liposomal vincristine (P<0.01), thus providing a 21% increase in lifespan for animals treated with the liposomal preparation. There was slightly greater weight loss in mice treated with free vincristine than those given liposomal vincristine. Measurement of in vitro colony forming bone marrow progenitor cells in similarly treated, tumour-free mice, showed no difference in progenitor cell survival between mice that received either type of vincristine. We conclude that encapsulating vincristine in liposomes improves the therapeutic index of this drug measured in mice bearing human leukaemia. This may lead to use of the drug in conventional combination chemotherapy with greater safety or, in this setting, at higher dosage.     

The functional anatomy of imagining and perceiving colour

OBJECTIVE: To determine whether the progression of urinary albumin excretion rate (AER) is higher during puberty than before or after this period. RESEARCH DESIGN AND METHODS: A prospective study was conducted in which normoalbuminuric prepubertal (n = 20), pubertal (n = 28), and postpubertal (n = 26) IDDM groups matched for diabetes duration and long-term metabolic control were followed for 3 years. At 6-month intervals, 24-h urine collection was used to determine AER. RESULTS: AER increased significantly over a period of 3 years in the pubertal (P = 0.001) and postpubertal (P = 0.003) subjects but not in prepubertal subjects. The annual progression of AER was significantly higher in the pubertal group than in the prepubertal (P = 0.001) or postpubertal (P = 0.001) groups. Six pubertal, two postpubertal, and none of the prepubertal subjects developed microalbuminuria (AER > or = 20 micrograms/min on two consecutive occasions) over a 3-year period (P = 0.047). Multiple logistic regression analysis showed that the risk of development of microalbuminuria was increased in pubertal subjects compared with the prepubertal and postpubertal subjects (adjusted relative risk [95% CI]: 4.3 [1.5-9.3], P = 0.012, and 2.1 [1.1-5.0], P = 0.023, respectively). CONCLUSIONS: Puberty represents an independent risk of the development of microalbuminuria in diabetes. This findings suggests that the endocrine changes of puberty lead to an accelerated process of early kidney damage in diabetes. In pediatric diabetes care, screening for microalbuminuria is needed soon after the onset of puberty.     

Analyses of the 1990 chest health survey of china clay workers

During 1990 all present and retired china clay workers in the United Kingdom were invited to take part in a chest health survey. A total of 4401 china clay workers participated representing over 70% of current employees and 17% of pensioners. The survey consisted of a chest x ray film, lung function measurements, and a questionnaire on respiratory symptoms and smoking habits. The chest x ray films were read by three readers to the International Labour Office (ILO) 1980 classification. Full details of occupational history for each participant were available and for each employee an estimate of total exposure to china clay dust was derived from representative dust concentrations for each location and job. These were based on measured dust concentrations after 1978 and on estimates before 1978. Analyses of the data were carried out to investigate the relations between exposure, x ray film category, lung function, and respiratory symptoms. The percentage of people with small opacities greater than major x ray film category 1 was 0.8% (lower than in previous studies). Dust concentrations have been reduced in recent years, averaging 1.7 mg m-3 for dryers in 1990 compared with 3.5 mg m-3 in 1978. The lower effect of exposure after 1971, compared with earlier exposure, was confirmed by the analyses. After 1971 the milling of dried china clay (Atritor mills) was found to be the occupation with the highest effect on x ray film category. The relation between total exposure to china clay dust and x ray film category is such that a typical non-smoker worker employed in the most dusty of current occupations may expect to reach the lower limit of category 1 after about 42 years continuous employment in that job at current exposures. Both forced vital capacity (FVC) and forced expiratory volume in one second (FEV1) were found (as in other studies) to decline with age, more rapidly for smokers than non-smokers at the rates for FVC of 0.035 l/y and 0.033 l/y, whereas for FEV1 the rates are 0.039 l/y for smokers and 0.034 l/y for non-smokers. Changes in x ray film category are also related to lung function , a change of one major category being equivalent to about six years of aging in its effect on FEV1.     

Evolution of the mitochondrial ATPase 6 gene in Drosophila: unusually high level of polymorphism in D. melanogaster

We have determined 1990 bp mitochondrial DNA sequence which extends from 3' end of the cytochrome oxidase subunit I (COI) gene to 5' end of the COIII gene from two sibling species of Drosophila, D. simulans and D. mauritiana. Analyses of the sequences and part of the NADH dehydrogenase subunit 2 gene and the COI gene together with those from D. melanogaster and D. yakuba revealed that amino-acid substitution rate of the ATPase 6 gene seems to be higher in some strains of D. melanogaster than in the other species. High level of amino-acid polymorphism in this gene was observed in D. melanogaster. Synonymous substitution rate is relatively constant in all the genes examined, suggesting that mutation rate is not higher in the ATPase 6 gene of D. melanogaster. The amino-acid substitutions found specifically in D. melanogaster are at the sites which are not conserved among mammals, yeast and E. coli. These sites of the ATPase 6 gene might lose the selective constraint in D. melanogaster, and the amino-acid substitutions can be explained by neutral mutations and random genetic drift.     

Maximal functional capacity in patients with endomyocardial fibrosis

We evaluated objectively the cardiocirculatory dysfunction of patients with EMF, and related the functional class (FC-NYHA) to the data obtained by analysis of maximal functional capacity. We studied 55 subjects, divided into three groups: group 1 (G1) 21 (38.1%) normal persons, group 2 (G2) seven (12.7%) patients with EMF who were in FC I or II, and group 3 (G3) 27 (49%) patients in FC III or IV. Maximal oxygen consumption (VO2max) and O2 pulse index (PO2max) were obtained using a Beckman computerized gas analyser. The mean values were significantly different among the three groups. We conclude that the greater the clinical impairment, the greater the alterations that occur in the indices of cardiac function.     

Agonists and antagonists for lipopolysaccharide-induced cytokines

Agonistic and antagonistic properties of LPS and partial structures in the induction of cytokines are reviewed. Studies on structure-activity relationships of LPS and lipid A with human mononuclear cells reveal that S- and notably R-form LPS are very potent cytokine inducers. Synthetic E. coli lipid A is somewhat less active, whereas synthetic S. minnesota-type lipid A is significantly less active. Pentaacylated forms of lipid A are less potent than hexaacylated forms, and tetraacylated synthetic precursor Ia and bisacylated disaccharides and monosaccharides are completely inactive, indicating that a structure-dependent hierarchy of LPS and lipid A partial structures determines the monokine-inducing capacity in human mononuclear cells. Precursor Ia is a potent LPS antagonist. The mechanism of its inhibitory activity is shown to be due to competitive binding to cellular binding sites (receptors). Proinflammatory and antiinflammatory cytokines, receptor antagonists, and soluble cytokine receptors influence the cytokine-inducing activity of LPS, suggesting a complex regulatory network.     

Activation of protein kinase A contributes to the expression but not the induction of long-term hyperexcitability caused by axotomy of Aplysia sensory neurons

Nociceptive sensory neurons (SNs) in Aplysia provide useful models to study both memory and adaptive responses to nerve injury. Induction of long-term memory in many species, including Aplysia, is thought to depend on activation of cAMP-dependent protein kinase (PKA). Because Aplysia SNs display similar alterations in models of memory and after nerve injury, a plausible hypothesis is that axotomy triggers memory-like modifications by activating PKA in damaged axons. The present study disproves this hypothesis. SN axotomy was produced by (1) dissociation of somata from the ganglion [which is shown to induce long-term hyperexcitability (LTH)], (2) transection of neurites of dissociated SNs growing in vitro, or (3) peripheral nerve crush. Application of the competitive PKA inhibitor Rp-8-CPT-cAMPS at the time of axotomy failed to alter the induction of LTH by each form of axotomy, although the inhibitor antagonized hyperexcitability produced by 5-HT application. Strong activation of PKA in the nerve by coapplication of a membrane-permeant analog of cAMP and a phosphodiesterase inhibitor was not sufficient to induce LTH of either the SN somata or axons. Furthermore, nerve crush failed to activate axonal PKA or stimulate its retrograde transport. Therefore, PKA activation plays little if any role in the induction of LTH by axotomy. However, the expression of LTH was reduced by intracellular injection of the highly specific PKA inhibitor PKI several days after nerve crush. This suggests that long-lasting activation of PKA in or near the soma contributes to the maintenance of long-term modifications produced by nerve injury.