Structure-function analysis of a series of glucagon-like peptide-1 analogs

We have used NMR in conjunction with measurements of functional bioactivity to define the receptor-binding structure of glucagon-like peptide-1 (GLP-1.) Identification of the important residues for binding was accomplished by the substitution of amino acids at sites that seemed likely, from an examination of the amino acid sequence and from previously published observations, to be important in the three-dimensional (3D) structure of the molecule. Identification of the receptor-bound conformation of GLP-1, because it is a flexible peptide, required constraint of the peptide backbone into a predetermined 3D structure. Constraint was achieved by the introduction of disulfide bonds and specific side chain-side chain cross-links. The biological relevance of the synthetic structure of each rigidified peptide was assessed by measurement of its ability to bind to the receptor present on RINm5F cells and to elicit a functional response, cyclic AMP production. NMR solution structures were obtained for the most biologically relevant of these analogs. The results of this study indicated that the residues necessary for the biological activity of GLP-1 occupy approximately three equally-spaced regions of the peptide 3D structure, at the corners of an equilateral triangle whose sides are, at a minimum estimate, 12-15A.

Phosphotyrosine phosphatase and tyrosine kinase inhibition modulate airway pressure-induced lung injury

We determined whether drugs which modulate the state of protein tyrosine phosphorylation could alter the threshold for high airway pressure-induced microvascular injury in isolated perfused rat lungs. Lungs were ventilated for successive 30-min periods with peak inflation pressures (PIP) of 7, 20, 30, and 35 cmH2O followed by measurement of the capillary filtration coefficient (Kfc), a sensitive index of hydraulic conductance. In untreated control lungs, Kfc increased by 1.3- and 3.3-fold relative to baseline (7 cmH2O PIP) after ventilation with 30 and 35 cmH2O PIP. However, in lungs treated with 100 microM phenylarsine oxide (a phosphotyrosine phosphatase inhibitor), Kfc increased by 4.7- and 16.4-fold relative to baseline at these PIP values. In lungs treated with 50 microM genistein (a tyrosine kinase inhibitor), Kfc increased significantly only at 35 cmH2O PIP, and the three groups were significantly different from each other. Thus phosphotyrosine phosphatase inhibition increased the susceptibility of rat lungs to high-PIP injury, and tyrosine kinase inhibition attenuated the injury relative to the high-PIP control lungs.

Plasma glucose levels are reduced in rats and mice treated with an inhibitor of glucose-6-phosphate translocase

The activity of glucose-6-phosphatase (G-6-Pase) in isolated rat microsomes was inhibited by a new selective inhibitor of the multi-subunit G-6-Pase system, 1-[2-(4-chloro-phenyl)-cyclopropylmethoxy]-3,4-dihydroxy-5-(3-imid azo[4,5-b]pyridin-1-yl-3-phenyl-acryloyloxy)-cyclohexanecarboxylic acid (compound A) with a 50% inhibitory concentration (IC50) of approximately 10 nmol/l. Compound A (500 nmol/l) inhibited the uptake of [14C]glucose-6-phosphate (G-6-P) into intact isolated rat microsomes, confirming that this agent blocks G-6-P translocation, as suggested by previous studies using intact and permeabilized microsomes. The inhibition of microsomal G-6-P transport by compound A was associated with inhibition of the rate of glucose output from rat hepatocytes incubated in the presence of 25 nmol/l glucagon (IC50 approximately 320 nmol/l.) Compound A (1 micromol/l) also inhibited the basal rate of glucose production by rat hepatocytes by 47%. Intraperitoneal administration of compound A to fasted mice lowered circulating plasma glucose concentrations dose-dependently at doses as low as 1 mg/kg. This effect was comparatively short-lived; glucose lowering was maximal at 30 min after dosing with 100 mg/kg compound A (-71%) and declined thereafter, being reversed within 3 h. A similar time course of glycemic response was observed in fasted rats; glucose lowering was maximal 30 min after dosing with 100 mg/kg compound A (-36%) and declined until the effect was fully reversed by 3 h postdose. In rats subjected to compound A treatment, liver glycogen content was increased. G-6-P and lactate levels were maximally elevated 30 min after dosing and declined thereafter. Cumulatively, these results suggest that the mechanism of glucose lowering by compound A was via inhibition of G-6-Pase activity, mediated through inhibition of the T1 subunit of the microsomal G-6-Pase enzyme system. Drug levels measured over the same time course as that used to assess in vivo efficacy peaked within 30 min of administration, then declined, which is consistent with the transient changes in plasma glucose and liver metabolites.

Postmortem diagnosis of leukodystrophies

Leukodystrophies are progressive disorders involving the development and maintenance of myelin in the central and peripheral nervous systems. Although relatively uncommon, leukodystrophic disorders may be undiagnosed or misdiagnosed during life, and may appear as "sudden death." In such instances, these victims may be referred to a forensic pathologist. In general, leukodystrophies are inherited in an autosomal recessive manner so that proper postmortem diagnosis by the forensic pathologist is extremely important to the decendant's family for future family planning.

Species- and sex-related differences in metabolism of trichloroethylene to yield chloral and trichloroethanol in mouse, rat, and human liver microsomes

Trichloroethylene (TRI) has been shown to cause a variety of tumors, particularly in mouse liver and lung and rat kidney. However, a clear association between exposure to TRI and cancer development in humans has not been established. Because TRI metabolism by cytochrome P450s has been implicated in the mechanisms of TRI-induced carcinogenicity in mice, the purpose of the present study was to characterize the kinetics of TRI oxidation in male and female mouse, rat, and human liver microsomes to possibly allow for a better assessment of human risk. Methods were developed to detect and quantitate chloral, trichloroethanol, trichloroacetic acid, dichloroacetic acid, chloroacetic acid, glyoxylic acid, and oxalic acid, known TRI metabolites in rodents or humans. However, only chloral and its further metabolite, trichloroethanol, were consistently detected in the various liver microsomes in the presence of NADPH. Chloral was the major metabolite detected, and its levels were species- and sex-dependent; the amounts of trichloroethanol detected were also species- and sex-dependent but never exceeded 15% of total metabolites. Double-reciprocal plots of metabolite formation with male and female rat and human liver microsomes indicated biphasic kinetics, but this trend was not observed with microsomes from male or female mouse liver. The Vmax data are consistent, with male and female mice being more susceptible to TRI-induced liver carcinogenicity than male rats. However, the Vmax/Km ratios in male and female rat liver microsomes, in comparison with the male mouse liver microsomes, did not correlate with tumor incidences in these tissues. Furthermore, as only two out of six human liver samples examined exhibited Vmax/Km ratios similar or higher than the ratio obtained with male mouse liver, humans may vary in their toxic response after TRI exposure.

Customer satisfaction and self-reported treatment outcomes among psychiatric inpatients

OBJECTIVE

Relationships among different dimensions of patient satisfaction and selected demographic, clinical, and outcome variables were explored in a sample of severely ill people receiving inpatient psychiatric services.

METHOD

The sample consisted of 81 patients admitted to and discharged from an inpatient psychiatric unit at a midwestern Veterans Affairs medical center. Stepwise multiple regression was used to examine the relationship between patient satisfaction and self-reported changes in quality of life, symptomatology, and level of functioning as measured by the Treatment Outcome Profile. Other variables such as diagnosis, length of stay, employment, living situation, and prior psychiatric and substance abuse treatment were also considered. A subsample of the most satisfied and dissatisfied patients was chosen to further explore variables contributing to satisfaction with services.

RESULTS

Patient satisfaction was related to initial level of functioning, certain diagnoses, and treatment gains. Clinicians were highly accurate in identifying patients who were satisfied, based on blind chart reviews.

CONCLUSIONS

This study underscores the significant relationships between patient satisfaction, psychiatric diagnosis, and other outcome measures, and argues for the validity and utility of patient satisfaction measures in assessing the efficacy of inpatient care.

Glutathione conjugation of perchloroethylene in rats and mice in vitro: sex-, species-, and tissue-dependent differences

Perchloroethylene (Per)-induced nephrotoxicity and nephrocarcinogenicity have been associated with metabolism by the glutathione (GSH) conjugation pathway to form S-(1,2,2-trichlorovinyl)glutathione (TCVG). Formation of TCVG was determined in incubations of Per and GSH with isolated renal cortical cells and hepatocytes from male and female Fischer 344 rats and with renal and hepatic cytosol and microsomes from male and female Fischer 344 rats and B6C3F1 mice. The goal was to assess the role of metabolism in the sex and species dependence of susceptibility to Per-induced toxicity. A key finding was that GSH conjugation of Per occurs in kidney as well as in liver. Although amounts of TCVG formation in isolated kidney cells and hepatocytes from male and female rats were generally similar, TCVG formation in subcellular fractions showed marked sex, species, and tissue dependence. This may be due to the presence of multiple pathways for metabolism in intact cells, whereas only the GSH conjugation pathway is active in the subcellular fractions under the present assay conditions. TCVG formation in kidney and liver subcellular fractions from both male rats and mice were invariably higher than corresponding values in female rats and mice. Amounts of TCVG formation in rat liver subcellular fractions were approximately 10-fold higher than in corresponding fractions from rat kidney. Although rats are more susceptible to Per-induced renal tumors than mice, amounts of TCVG formation were 7- to 10-fold higher in mouse kidney subcellular fractions and 2- to 5-fold higher in mouse liver subcellular fractions of both sexes compared to corresponding fractions from the rat. Hence, although the higher amounts of TCVG formation in liver and kidney from male rats correspond to their higher susceptibility to Per-induced renal tumors compared with female rats, the markedly higher amounts of TCVG formation in mice compared with rats suggest that other enzymatic or transport steps in the handling of Per in mice contribute to their relatively low susceptibility to Per-induced renal tumors

Islet amyloid-associated diabetes in obese A(vy)/a mice expressing human islet amyloid polypeptide

We have previously shown that hemizygous transgenic mice expressing human islet amyloid polypeptide (hIAPP) in pancreatic beta-cells have no diabetic phenotype, whereas in the homozygous state, they developed severe, early-onset hyperglycemia associated with impaired insulin secretion and beta-cell death. We investigated the possibility that when the hemizygous mice are crossed onto an obese, insulin-resistant strain such as agouti viable yellow (A(vy)/a), they would exhibit a phenotype more akin to human type 2 diabetes. The hIAPP-expressing A(vy) males (TG-Y) displayed fasting hyperglycemia at 90 days of age and by 1 year progressed to severe hyperglycemia relative to their nontransgenic counterparts. Plasma insulin concentrations and pancreatic insulin content dropped 10- to 20-fold, suggesting severe impairment of beta-cell function. Histopathological findings revealed beta-cell degeneration and loss consistent with the drop in the plasma insulin concentration. In addition, large deposits of IAPP amyloid were present in TG-Y islets. We conclude that in transgenic mice expressing hIAPP, insulin resistance can induce overt, slow-onset diabetes associated with islet amyloid and decreased beta-cell mass.

Gadolinium prevents high airway pressure-induced permeability increases in isolated rat lungs

To determine the initial signaling event in the vascular permeability increase after high airway pressure injury, we compared groups of lungs ventilated at different peak inflation pressures (PIPs) with (gadolinium group) and without (control group) infusion of 20 microM gadolinium chloride, an inhibitor of endothelial stretch-activated cation channels. Microvascular permeability was assessed by using the capillary filtration coefficient (Kfc), a measure of capillary hydraulic conductivity. Kfc was measured after ventilation for 30-min periods with 7, 20, and 30 cmH2O PIP with 3 cmH2O positive end-expiratory pressure and with 35 cmH2O PIP with 8 cmH2O positive end-expiratory pressure. In control lungs, Kfc increased significantly to 1.8 and 3.7 times baseline after 30 and 35 cmH2O PIP, respectively. In the gadolinium group, Kfc was unchanged from baseline (0.060 +/- 0.010 ml . min-1 . cmH2O-1 . 100 g-1) after any PIP ventilation period. Pulmonary vascular resistance increased significantly from baseline in both groups before the last Kfc measurement but was not different between groups. These results suggest that microvascular permeability is actively modulated by a cellular response to mechanical injury and that stretch-activated cation channels may initiate this response through increases in intracellular calcium concentration.

Blood flow vs. venous pressure effects on filtration coefficient in oleic acid-injured lung

On the basis of changes in capillary filtration coefficient (Kfc) in 24 rabbit lungs, we determined whether elevations in pulmonary venous pressure (Ppv) or blood flow (BF) produced differences in filtration surface area in oleic acid-injured (OA) or control (Con) lungs. Lungs were cyclically ventilated and perfused under zone 3 conditions by using blood and 5% albumin with no pharmacological modulation of vascular tone. Pulmonary arterial, venous, and capillary pressures were measured by using arterial, venous, and double occlusion. Before and during each Kfc-measurement maneuver, microvascular/total vascular compliance was measured by using venous occlusion. Kfc was measured before and 30 min after injury, by using a Ppv elevation of 7 cmH2O or a BF elevation from 1 to 2 l . min-1 . 100 g-1 to obtain a similar double occlusion pressure. Pulmonary arterial pressure increased more with BF than with Ppv in both Con and OA lungs [29 +/- 2 vs. 19 +/- 0.7 (means +/- SE) cmH2O; P < 0. 001]. In OA lungs compared with Con lungs, values of Kfc (200 +/- 40 vs. 83 +/- 14%, respectively; P < 0.01) and microvascular/total vascular compliance ratio (86 +/- 4 vs. 68 +/- 5%, respectively; P < 0.01) increased more with BF than with Ppv. In conclusion, for a given OA-induced increase in hydraulic conductivity, BF elevation increased filtration surface area more than did Ppv elevation. The steep pulmonary pressure profile induced by increased BF could result in the recruitment of injured capillaries and could also shift downstream the compression point of blind (zone 1) and open injured vessels (zone 2).

Age, depressive symptoms, and rheumatoid arthritis

OBJECTIVE

To examine the relationship between age and depression in persons with rheumatoid arthritis (RA).

METHODS

Two separate outpatient cohorts of persons with RA were studied. In both studies, the Center for Epidemiological Studies Depression Scale was administered to all subjects, and the prevalence of depressive symptoms was determined by age group. In the second study, data on additional measures of disease activity, pain, life stress, and coping were collected for use in multiple linear regression analyses.

RESULTS

In both samples, a significant correlation between age and depression was found; younger persons (age < or = 45 years) with RA were significantly more depressed, even after controlling for potentially confounding variables such as sex, marital status, antidepressant medication, arthritis medication, functional class, and disease duration.

CONCLUSION

The findings show that younger persons with RA are at higher risk for depressive symptoms than their older counterparts.

Glutathione conjugation of trichloroethylene in rats and mice: sex-, species-, and tissue-dependent differences

Glutathione (GSH) conjugation of trichloroethylene (Tri) to form S-(1,2-dichlorovinyl)glutathione (DCVG) has been implicated in the nephrotoxicity and nephrocarcinogenicity of Tri. Marked sex- and species-dependent differences exist, however, in the susceptibility to Tri-induced renal toxicity, with the male rat being the most susceptible. The present study, therefore, focuses on potential differences in the initial step of the GSH pathway. Rates of DCVG formation were measured in suspensions of isolated renal cortical cells and isolated hepatocytes from male and female Fischer 344 rats and in kidney and liver microsomes and cytosol from male and female Fischer 344 rats and B6C3F1 mice to determine if sex- and species-dependent differences in GSH conjugation correlate with susceptibility to renal toxicity from Tri. Rates of gamma-glutamyltransferase (GGT) with gamma-glutamyl-p-nitroanilide and glycylglycine as substrates and GSH S-transferase (GST) with 1-chloro-2,4-dinitrobenzene as substrate were also measured in liver and kidney subcellular fractions to provide further information on the biochemical basis of susceptibility to Tri. Rates of DCVG formation in rat kidney cells and kidney subcellular fractions were 5- to 20-fold lower than those in rat hepatocytes and liver subcellular fractions. Rates of DCVG formation in kidney cells and subcellular fractions were comparable in male and female rats with the exception of male rat kidney microsomes, where DCVG formation was below the limit of detection, and those in liver cells and subcellular fractions were >3-fold higher in male rats than in female rats. Rates of DCVG formation in mouse kidney subcellular fractions were approximately 10-fold higher than in corresponding fractions from the rat, whereas those in mouse liver subcellular fractions were 4- to 8-fold higher than in corresponding rat tissues, with rates in male mouse liver cytosol and microsomes being modestly higher than in corresponding fractions from female mice. GGT activity was barely detectable in livers, was about 20-fold higher in rat kidneys than in mouse kidneys, and was slightly higher in female rat kidneys than in male rat kidneys. GST activity with 1-chloro-2,4-dinitrobenzene as substrate exhibited tissue-, sex-, and species-dependent patterns that were generally similar to those with Tri as the substrate. These results suggest that the higher susceptibility to Tri-induced renal toxicity of male rats as compared with female rats correlates with rates of DCVG formation. The high rates of DCVG formation in mice, however, indicate that other factors, possibly including differences in activities of cysteine conjugate beta-lyase or N-acetyltransferase, may also be important determinants of the susceptibility to Tri.

Isoproterenol attenuates high vascular pressure-induced permeability increases in isolated rat lungs

To separate the contributions of cellular and basement membrane components of the alveolar capillary barrier to the increased microvascular permeability induced by high pulmonary venous pressures (Ppv), we subjected isolated rat lungs to increases in Ppv, which increased capillary filtration coefficient (Kfc) without significant hemorrhage (31 cmH2O) and with obvious extravasation of red blood cells (43 cmH2O). Isoproterenol (20 microM) was infused in one group (Iso) to identify a reversible cellular component of injury, and residual blood volumes were measured to assess extravasation of red blood cells through ruptured basement membranes. In untreated lungs (High Ppv group), Kfc increased 6.2 +/- 1.3 and 38.3 +/- 15.2 times baseline during the 31 and 43 cmH2O Ppv states. In Iso lungs, Kfc was 36.2% (P < 0.05) and 64.3% of that in the High Ppv group at these Ppv states. Residual blood volumes calculated from tissue hemoglobin contents were significantly increased by 53-66% in the high Ppv groups, compared with low vascular pressure controls, but there was no significant difference between High Ppv and Iso groups. Thus isoproterenol significantly attenuated vascular pressure-induced Kfc increases at moderate Ppv, possibly because of an endothelial effect, but it did not affect red cell extravasation at higher vascular pressures.

High vascular and airway pressures increase interstitial protein mRNA expression in isolated rat lungs

We hypothesized that wall stresses produced by high peak airway (Paw) and venous (Ppv) pressures would increase mRNA levels for structural proteins of the interstitial matrix in isolated rat lungs. Groups of lungs (n = 6) were perfused for 4 h at a peak Paw of 35 cmH2O (HiPaw), cyclical peak Ppv of 28 cmH2O (HiPv), or baseline vascular and airway pressures (LoPress). In two separate groups, comparable peak pressures increased capillary filtration coefficient fourfold in each group. Northern blots were probed for mRNA of alpha 1(I), alpha 1(III), and alpha 2(IV) procollagen chains, laminin B chain, fibronectin, and transforming growth factor-beta 1, and densities were normalized to 18S rRNA. mRNA was significantly higher in the HiPv group for type I (4.3-fold) and type III (3.8-fold) procollagen and laminin B chain (4.8-fold) and in the HiPaw group for type I (2.4-fold) and type IV (4.5-fold) procollagen and laminin B chain (2.3-fold) than in the LoPress group. Only fibronectin mRNA was significantly increased (3.9-fold) in the LoPress group relative to unperfused lungs. Estimated wall stresses were highest for alveolar septa in the HiPaw group and for capillaries in the HiPv group. The different patterns of mRNA expression are attributed to different regional stresses or extent of injury.

Vascular tree structure affects lung blood flow heterogeneity simulated in three dimensions

Pulmonary arterial tree structures related to blood flow heterogeneity were simulated by using a symmetrical, bifurcating model in three-dimensional space. The branch angle (Theta), daughter-parent length ratio (rL), branch rotation angle (phi), and branch fraction of parent flow (gamma) for a single bifurcation were defined and repeated sequentially through 11 generations. With phi fixed at 90 degrees , tree structures were generated with Theta between 60 and 90 degrees , rL between 0.65 and 0.85, and an initial segment length of 5.6 cm and sectioned into 1-cm3 samples for analysis. Blood flow relative dispersions (RD%) between 52 and 42% and fractal dimensions (Ds) between 1.20 and 1.15 in 1-cm3 samples were observed even with equal branch flows. When gamma not equal 0.5, RD% increased, but Ds either decreased with gravity bias of higher branch flows or increased with random assignment of higher flows. Blood flow gradients along gravity and centripetal vectors increased with biased flow assignment of higher flows, and blood flows correlated negatively with distance only when gamma not equal 0.5. Thus a recursive branching vascular tree structure simulated Ds and RD% values for blood flow heterogeneity similar to those observed experimentally in the pulmonary circulation due to differences in the number of terminal arterioles per 1-cm3 sample, but blood flow gradients and a negative correlation of flows with distance required unequal partitioning of blood flows at branch points.

Modulation of insulin secretion and glycemia by selective inhibition of cyclic AMP phosphodiesterase III

The effects of selective inhibition of cyclic AMP phosphodiesterase type III on insulin and glucose levels during an oral glucose challenge were evaluated in obese, diabetic ob/ob mice and in lean, non-diabetic littermates using the selective inhibitor, milrinone. Oral administration of milrinone increased plasma insulin levels both in ob/ob and in lean mice. Glucose tolerance was improved in lean, but not in ob/ob mice, where glucose levels were increased by milrinone treatment. In isolated hepatocytes from normal rats incubation with 200 microM milrinone caused a 30% increase in glucose release with a corresponding depletion of glycogen stores. Stimulation of isolated rat adipocytes with 200 microM milrinone increased glycerol release 7-fold. We conclude that selective inhibitors of cyclic AMP phosphodiesterase III are effective insulin secretagogues, but their therapeutic utility may be limited by their concurrent stimulation of lipolysis and hepatic glucose output.

Intracranial saccular (berry) aneurysm: a brief overview

An incidental saccular intracranial (berry) aneurysm is not an uncommon finding at autopsy. Rupture of such an aneurysm can produce severe neurologic deterioration and death, often without warning. Morbidity and mortality can be reduced in some patients with early surgical intervention. Familial aggregation of cerebral aneurysms occurs frequently enough to warrant screening of family members to diagnose an asymptomatic berry aneurysm. We review the etiology, clinicopathologic features, and natural history of berry aneurysms and aneurysm rupture, as well as the various screening methods. A careful examination of the cerebral vessels should be routine in every postmortem examination, regardless of the cause of death.

Outcomes of inpatients treated on a VA psychiatric unit and a substance abuse treatment unit

OBJECTIVE

The utility of the Treatment Outcome Profile (TOP) for measuring the effectiveness of acute inpatient psychiatric and substance abuse treatment was tested, including its internal reliability, validity, and sensitivity to treatment gains. The relationship between patients' satisfaction with services and treatment gains in quality of life, symptoms, and level of functioning was explored.

METHODS

A pre-post research design was used with consecutive admissions to an inpatient psychiatric unit (N = 66) and a substance abuse treatment unit (N = 88) at a VA medical center. At admission and at discharge, the TOP, a self-report instrument assessing quality of life, symptoms, level of functioning, and patient satisfaction with services (at discharge only) was completed. Multivariate analysis of variance and univariate analysis of variance were used to test differences in scores between admission and discharge.

RESULTS

Patients demonstrated significant treatment gains. Overall, compared with patients on the substance abuse unit, those receiving psychiatric treatment were more impaired at admission and had lower levels of self-reported therapeutic gain at discharge. Improvement for both groups occurred in quality of life, symptoms, and level of functioning. Both groups reported high levels of patient satisfaction, comparable with levels in other service industries. A high positive correlation (alpha = .61) was found between patient satisfaction and overall self-reported treatment gain.

CONCLUSIONS

The results indicate that it is important to compare treatment effectiveness as well as costs when seeking less costly alternatives to inpatient care. The TOP is a valid and sensitive outcome measurement tool. Patient satisfaction is an important outcome variable and positively related to treatment gains in quality of life, symptoms, and level of functioning.

Urea inhibits Na-K-2Cl cotransport in medullary thick ascending limb cells

We examined the effect of physiological concentrations of urea (100-500 mM) on Na-K-2Cl cotransport in cultured cells from mouse medullary thick ascending limb (mTAL). Urea acutely inhibited bumetanide-sensitive K influx in mTAL cells in a concentration-dependent fashion, with a statistically significant inhibition (19%) at 100 mM and 86% inhibition at 500 mM. The effect of urea was entirely reversible and was blocked by prior treatment with okadaic acid, a phosphatase inhibitor, suggesting that urea exerts its action upstream of the phosphorylation-dephosphorylation step. Cell volume was unchanged in the presence of 500 mM urea. The number of [3H]bumetanide binding sites, a measure of the number of functioning cotransporter sites, was decreased in the presence of urea, and the decrease in bumetanide binding was proportional to the decrease in bumetanide-sensitive K influx. Urea also stimulated the Ba-sensitive swelling-activated K efflux from mTAL cells. Thus urea, in concentrations that prevail in the renal medulla, alters ion transport in mTAL cells.

The importance of enhancing self-efficacy in rheumatoid arthritis

OBJECTIVE

To examine relationships among changes in self-efficacy and changes in other clinically relevant outcome measures.

METHOD

Subjects (n = 44) were participants in a prospective, randomized stress-management study followed over 15 months. Outcome measures included self-efficacy, depression, pain, health status, and disease activity.

RESULTS

Correlational analyses revealed significant associations between changes in self-efficacy (particularly total self-efficacy) and changes in selected measures of depression, pain, health status, and disease activity. The observed associations were not due to changes in medication regimen or to nonadherence to the stress-management program.

CONCLUSIONS

Evidence is provided that induced changes in self-efficacy following a stress-management program were significantly related to other clinically important outcome measures.

Escalation in response to persistent annoyance: groups versus individuals and gender effects

Reactions to persistent annoyance were studied with a new laboratory method. A standard escalation sequence was found, which involved the following order of tactics: requests for termination of the annoyance, impatient demands, complaints, angry statements, threats, harassment, and abuse. The further along a tactic was in this sequence, the fewer the people who used it. This pattern of results provided a good fit to a cascading Guttman scale, suggesting the existence of a standard "try-try-again" escalation script. Problem solving and appeals to a third party were intermediate in the escalation sequence but did not appear to be part of the standard script. Groups used more escalated tactics than individuals, apparently because of their greater activity level. Women used more escalated tactics than men, at least in part because of greater anger at being treated unfairly. Men were the targets of more escalated tactics than women.

A biopsychosocial model of disability in rheumatoid arthritis

OBJECTIVE

To test and cross-validate a model using disease activity, pain, and helplessness to predict future psychological and physical disability in persons with rheumatoid arthritis (RA) across time.

METHODS

Measures of disease activity, pain, helplessness, psychological function, and physical function were collected from 63 males with RA at baseline, 3 months, and 6 months. Path analytic methods were used to examine longitudinal relationships among these variables.

RESULTS

Path analysis revealed that pain and helplessness were significant mediators of the relationship between disease activity and future disability in RA; the predictive model withstood two cross-validations.

CONCLUSION

The findings suggest that pain and helplessness are key biopsychosocial variables that affect the development of disability in RA.

Role of p53 immunohistochemistry in differentiating reactive gliosis from malignant astrocytic lesions

P53 immunohistochemistry has been used to distinguish between malignant tumors and morphologically similar benign processes. In the central nervous system, a major diagnostic dilemma is caused by overlapping features of benign reactive astrocytic lesions and low-grade astrocytomas, especially with small biopsies. P53 immunoreactivity in astrocytes could be useful in differentiating benign reactive lesions from malignant astrocytomas. An immunohistochemical study on 110 brain lesions from 108 patients using a monoclonal antibody (DO-7) against p53 protein was conducted. Using the modified Ringertz and World Health Organization system, the specimens included 22 astrocytomas, 12 anaplastic astrocytomas, 42 glioblastoma multiforme tumors, three nonglial tumors, and 56 reactive astrocytic lesions to 25 neoplasms, nine infectious processes, six cerebrovascular disorders,one metabolic disorder, two vascular malformations, eleven degenerative/demyelinating lesions, and two unknown primary lesions. Immunoreactive astrocytic tumors included 12 (54%) astrocytomas, nine (75%) anaplastic astrocytomas, and 38 glioblastoma multiforme tumors (90%). Among the reactive astrocytic lesions, only five (9%) cases of progressive multifocal leukoencephalopathy were immunoreactive. These data demonstrate that p53 immunoreactivity in astrogliosis is unusual but is to be expected in astrocytomas and can help to differentiate reactive from neoplastic astrocytic lesions.

Eosinophilia-induced vascular and airway remodeling and hyperresponsiveness in rat lungs

We evaluated the effects of pulmonary infiltration of eosinophils without exogenous activators on airway and vascular hyperresponsiveness to muscarinic challenge in the lungs of rats infected with Toxocara [correction of Toxicara] canis, the canine round worm. Bronchoalveolar lavage of infected lungs produced 4.26 x 10(7) cells with 85% eosinophils, 15% mononuclear cells, and essentially no neutrophils. Eosinophils were present in the air spaces and interstitial spaces surrounding airways and vessels. The smooth muscle thickness increased about fourfold in large airways and vessels, and medium and small vessels were muscularized in infected lungs. In the T. canis-infected lungs, baseline airway resistance increased 288%, total vascular resistance (RT) increased 202%, and capillary filtration coefficient increased 208% compared with uninfected control lungs. Lung compliance was 56% of control. The concentration of acetylcholine that produced 50% of maximal response was 18.4 times greater for airway resistance and 18.7 times greater for RT in uninfected controls than in infected lungs. Isoproterenol (10(-4) M) decreased RT and peak airway pressure by 21% in infected lungs but had no significant effect on controls. We conclude that pulmonary interstitial infiltrates of eosinophils cause airway and vascular remodeling and increase baseline resistances and muscarinic reactivities of airways and vessels in rat lungs infected with T. canis.

Risk factors for depression in rheumatoid arthritis

OBJECTIVE

To identify risk factors for the development of depression in persons with rheumatoid arthritis (RA).

METHODS

Subjects were divided into depressed versus nondepressed groups on the basis of the Center for Epidemiologic Studies-Depression Scale; a range of psychological, pain-related, disease-related, and demographic variables were analyzed to predict depression. Both cross-sectional and longitudinal predictive models were examined.

RESULTS

A series of analyses, including multiple logistic regression, found that the optimal predictors of depression in RA were average daily stressors, confidence in one's ability to cope, and degree of physical disability. The model was successfully cross-validated on separate data sets (i.e., same subjects at different time points).

CONCLUSION

All of the identified risk factors for depression in RA are preventable to some extent and, therefore, should be addressed in comprehensive, rheumatology team care.

Self-efficacy predicting outcome among fibromyalgia subjects

OBJECTIVES

This study examined whether pretreatment self-efficacy and pre- to post-treatment changes in self-efficacy predict post-treatment tender point index, disease severity, pain, and physical activity.

METHODS

One hundred nine subjects with fibromyalgia were assessed before and after a 6-week training intervention. Measures included tender point index, physician ratings of disease severity, the visual analog scale for pain, the Physical Activities subscale of the Arthritis Impact Measurement Scales, and the Arthritis Self-Efficacy Scale.

RESULTS

Pretreatment self-efficacy significantly predicted post-treatment physical activity, with higher self-efficacy associated with better physical activity outcome. Changes in self-efficacy significantly predicted post-treatment tender point index, disease severity, and pain; improvements in self-efficacy were associated with better outcomes on each measure.

CONCLUSIONS

Higher levels of self-efficacy are associated with better outcome, and may mediate the effectiveness of rehabilitation-based treatment programs for fibromyalgia.

Comparison of the glucose dependency of glucagon-like peptide-1 (7-37) and glyburide in vitro and in vivo

The purpose of the present study was to compare the glucose dependency of the insulin secretagogue activity of the sulfonylurea, glyburide, versus that of glucagon-like peptide-1(7-37) [GLP-1(7-37)] in vitro and in vivo. In freshly isolated rat islets, maximally effective concentrations of glyburide (10 micromol/L) and GLP-1(7-37) (10 nmol/L) were equally effective in stimulating insulin secretion in the presence of 15 mmol/L glucose (2.4-fold increase relative to 15 nmol/L glucose alone). At 5 nmol/L glucose, both agents increased insulin secretion, but the effect for glyburide was threefold greater than for GLP-1(7-37) (122% and 41% increase in insulin secretion, respectively). In conscious catheterized rats infused with glucose at a variable rate to clamp plasma glucose concentration at 11 mmol/L, glyburide (1 mg/kg orally) and GLP -1(7-37) (infused intravenously [IV] at 5 pmol/min/kg) produced similar increase in insulin levels (1.8-fold relative to the respective vehicle controls) that were sustained through 60 minutes of measurement. These doses of GLP-1(7-37) and glyburide were then administered to fasted and fed rats (basal plasma glucose concentration, 5.8 and 7.3 mmol/L, respectively). Relative to the vehicle control group, GLP-1(7-37) infusion produced a transitory increase (30%) in plasma insulin concentration and a modest sustained decrease (10% to 20%) in glucose in both fasted and fed rats, whereas glyburide induced a sustained 2.4- and 1.7-fold increase in plasma insulin concentration in fasted and fed rats, respectively, and a 50% decrease in plasma glucose in both fasted and fed rats. Results of these studies demonstrate the higher glucose threshold for the insulin secretagogue activity of GLP-1(7-37) relative to glyburide in vitro and in vivo.

Aicardi syndrome: a morphologic description with particular reference to intracytoplasmic inclusions in cortical astrocytes

Aicardi syndrome is characterized by agenesis of the corpus callosum, infantile spasms, and ocular anomalies. Very few morphologic descriptions have been made of the central nervous system of children with this syndrome. We performed a postmortem examination of the brain of a 13-year-old girl with clinically well-documented Aicardi syndrome. Gross examination revealed a small brain (745 g) with the right cerebral and cerebellar hemispheres smaller than the left. There was agenesis of the corpus callosum, and ectopic gray matter was scattered throughout the cerebral hemispheres. Both choroid plexus and arachnoid cysts were present. Microscopic examination revealed indistinct cortical layering and multiple foci of ectopic gray matter. The cerebellar sections were altered by focal atrophy with gliosis and Purkinje cell dropout. Multiple sections of cerebrum contained astrocytes with coarse, paranuclear, eosinophilic inclusions. Electron microscopy, immunohistochemistry, and special stains further defined these inclusions, which we speculate represent a degenerative process.

Regional tracheal blood flow during conventional and high-frequency jet ventilation in suckling pigs

OBJECTIVE

To determine whether intubation and ventilation with either conventional mechanical ventilation or high-frequency jet ventilation, using dry or humidified gas, could induce regional tracheal ischemia and serve as a basis for the tracheal necrosis observed clinically during ventilation.

DESIGN

Prospective, multiple group, controlled experimental study.

SETTING

Medical school research laboratory.

SUBJECTS

Twenty, 3- to 5-wk-old suckling pigs.

INTERVENTIONS

Anesthetized, closed-chest piglets were intubated and ventilated for 30 mins with conventional mechanical ventilation and then ventilated for 2 additional hrs with either conventional mechanical ventilation or high-frequency jet ventilation. Groups were also ventilated, using both modes of ventilation, with either 37 degrees C humidified gas or 25 degrees C dry gas.

MEASUREMENTS AND MAIN RESULTS

Blood flow groups were compared during spontaneous breathing, conventional mechanical ventilation, high-frequency jet ventilation and both ventilation modes, using 37 degrees C humidified or 22 degrees C dry inspired gas. Groups were compared, using an analysis of variance with a Newman-Keul's post-test. Regional tracheal blood flow was measured, using radioactive microspheres. Cardiac output and organ blood flows were also monitored. Tracheal blood flow increased 10.3-fold within 30 mins after intubation, but there were no significant differences in regional or total tracheal blood flow between conventional mechanical ventilation and high-frequency jet ventilation, using 37 degrees C humidified gas. Tracheal blood flow was increased further using high-frequency jet ventilation and 25 degrees C dry gas but not conventional mechanical ventilation with dry gas. Although ventilation reduced cardiac output by approximately 30%, there were no significant differences in organ distribution between modes of ventilation.

CONCLUSIONS

Acute tracheal hyperemia occurred with intubation and ventilation with both conventional mechanical ventilation and high-frequency jet ventilation but no differences were observed between ventilation modes. Hyperemia was further increased with cool, dry inspired gas, using high-frequency jet ventilation but not conventional mechanical ventilation. Although acute tracheal ischemia was not produced by high-frequency jet ventilation or conventional mechanical ventilation, factors which alter the balance between arterial supply and metabolic demand or induce inflammation may contribute to the tracheal necrosis reported during sustained ventilation.

Cyclic AMP phosphodiesterases of human and rat islets of Langerhans: contributions of types III and IV to the modulation of insulin secretion

This study evaluated the contribution of isozymes of cAMP phosphodiesterase (PDE) to total PDE activity in human and rat islets using type-selective inhibitors. The effects of selected PDE inhibitors on insulin secretion from human and rat islets were also measured in order to assess the contribution of the various PDE isozymes to the modulation of insulin secretion. The data suggest that PDE III is quantitatively the most important PDE isozyme present in islets, accounting for up to 70% of the total activity. Lower, but measurable, levels of PDE IV activity were present. Approximately 20% of islet PDE is not inhibitable by agents selective either for PDE III or IV. Selective inhibition of PDE III stimulated insulin secretion, but inhibition of PDE IV had no effect. The effects of type-selective inhibitors on PDE activity and insulin secretion were similar in human and rat islets.

Effects of stress management on clinical outcomes in rheumatoid arthritis

OBJECTIVE

To examine the effects of stress-management training on clinical outcomes in persons with rheumatoid arthritis (RA).

METHODS

Patients with RA (n = 141) were randomly assigned to 1 of 3 groups: a stress management group, an attention control group, or a standard care control group. The stress management and the attention control groups received a 10-week intervention followed by an additional 15-month maintenance phase.

RESULTS

The stress management group showed statistically significant improvements on measures of helplessness, self-efficacy, coping, pain, and health status. Selected beneficial effects were still detectable at the 15-month followup evaluation.

CONCLUSION

The data indicated that stress management interventions are capable of producing important clinical benefits for persons with RA.

Renal activation of trichloroethene and S-(1,2-dichlorovinyl)-L-cysteine and cell proliferative responses in the kidneys of F344 rats and B6C3F1 mice

Covalent binding of reactive intermediates formed by renal beta-lyase activation of S-(1,2-dichlorovinyl)-L-cysteine (DCVC) has been suggested to be responsible for the greater renal sensitivity of rats than mice to the carcinogenic effects of chronic treatment with trichloroethene (TRI). Previous work demonstrated that the activation of DCVC results in acid-labile adducts to protein that can be distinguished from adducts formed by other pathways of TRI metabolism. By analyzing acid-labile adduct formation, the relationship between DCVC formation and activation from TRI and increases in rates of cell division in the kidneys of male F344 rats and B6C3F1 mice could be investigated. The delivered dose of DCVC from an oral dose of 1000 mg/kg TRI was approximately six times greater in rats than mice. However, renal activation of DCVC in mice was approximately 12 times greater than in rats. Therefore, the overall activation of TRI was about two times greater in mice than rats. Induction of cell replication in liver and kidney following doses of 1, 5, or 25 mg/kg DCVC or 1000 mg/kg TRI was also measured through the use of miniosmotic pumps that delivered BrdU subcutaneously for 3 d. Acid-labile adduct formation from DCVC and TRI displayed a consistent relationship with increased cell replication in mice and between mice and rats. Both cell replication and acid-labile adduct formation in rats given 25 mg/kg DCVC were approximately equal to that observed in mice given 1 mg/kg. Increased cell replication was not observed in rats receiving 1 or 5 mg/kg DCVC or 1000 mg/kg TRI, nor were there histological signs of nephrotoxicity. Thus, net activation of TRI by the cysteine S-conjugate pathway was found to be greater in mice than rats and these findings appeared related to differences in cell proliferative responses of the kidneys of the two species. Based on these data, it would appear that other factors must contribute to the greater sensitivity of the rat to the induction of renal carcinogenesis by TRI.

Acid-labile adducts to protein can be used as indicators of the cysteine S-conjugate pathway of trichloroethene metabolism

Covalent binding of radiolabel to tissue proteins following [14C]trichloroethene (TRI) exposure has been used as a measure of TRI activation. Gross binding of 14C label does not differentiate between alternate routes of metabolism and can be confounded when there is significant metabolic incorporation of radiolabel. We examined the covalent association of 14C label to hepatic and renal proteins in male F344 rats and B6C3F1 mice following oral treatment with [14C]TRI and three metabolites of TRI: [14C]trichloroacetate (TCA), [14C]dichloroacetate (DCA), and [14C]dichlorovinylcysteine (DCVC) in vivo. Association of radiolabel from [14C]TRI with hepatic proteins reached a maximum at 2 and 4 h in mouse and rat hepatic proteins, respectively. Association of radiolabel with renal proteins reached a maximum at 8 h in both species. An approach was developed based upon formation of protein adducts that release acetate and monochloroacetate (MCA) on acid hydrolysis. These adducts were found to be specifically associated with the activation of DCVC to reactive intermediates. Acetate and MCA were identified by using two different conditions of high-performance liquid chromatography (HPLC) separation with differing selectivity. Diethylmaleate and aminooxyacetic acid pretreatment inhibited the formation of these adducts from TRI, consistent with requirements for glutathione and beta-lyase. No evidence of these adducts was detected following [14C]TCA and [14C]DCA treatment. Renal acid-labile adduct formation from 25 mg/kg DCVC was approximately 12-fold greater in male B6C3F1 mice than in male F344 rats. They accounted for 7.8 and 4.6% of the total adducts to renal protein in rats and mice, respectively. Acid-labile adducts formed from 1000 mg/kg TRI were approximately two times greater in mice than rats. In this case, they accounted for 1.4 and 3.3% of the total adduct formed in renal proteins from TRI (corrected for metabolic incorporation), respectively. This greater dilution of adducts associated with DCVC in renal proteins of the rat suggests that covalent binding of TRI has less specificity for the DCVC pathway in rats than in mice.

The implications of depression for pain and disability in rheumatoid arthritis

Depression in rheumatoid arthritis (RA) affects many, but by no means all, persons with the disease. There is evidence that depression bears a significant relationship to pain in RA, although the causal direction is not entirely clear. Likewise, there is strong evidence that depression is a major contributor to the RA disability. Therefore, prevention, early diagnosis, and aggressive treatment of depression are needed to minimize the disability associated with RA.

Glucose-dependent action of glucagon-like peptide-1 (7-37) in vivo during short- or long-term administration

In vitro, truncated glucagon-like peptides [GLP-1(7-36)-amide and GLP-1(7-37)] increase insulin secretion in a glucose-dependent manner, and desensitization to the action of GLP-1(7-37) has been demonstrated acutely with high concentrations. The purpose of these studies was to evaluate the glucose dependency and threshold of GLP-1(7-37) action in normal rats and in a rat model of type II diabetes and to assess the effects of long-term administration in vivo. All studies were conducted in conscious catheterized rats. An intravenous (IV) infusion of GLP-1(7-37) at 0.5, 5, or 50 pmol/min/kg during the second hour of a 2-hour 11-mmol/L hyperglycemic clamp in Sprague-Dawley rats produced a dose-related enhancement of the glucose-induced increase in plasma insulin concentration. A 1-hour infusion of a submaximal dose of GLP-1(7-37) (5 pmol/min/kg IV) in fasted and fed Sprague-Dawley rats produced small transient increases in plasma insulin (incremental increases above basal, 72 +/- 27 and 96 +/- 28 pmol/L, respectively) and decreases in plasma glucose (to levels > or = 5.2 mmol/L). Infusion of GLP-1(7-37) (5 pmol/min/kg IV) during a hyperglycemic clamp at two sequentially increasing concentrations of glucose, 11 and 17 mmol/L, produced incremental increases in insulin of 600 and 1,200 pmol/L, respectively, relative to levels in clamped control rats. Similarly, infusion of GLP-1(7-37) (5 pmol/min/kg IV) in hyperinsulinemic, hyperglycemic Zucker diabetic fatty (ZDF) rats produced a transitory increase in plasma insulin concentration and normalized the plasma glucose concentration.(ABSTRACT TRUNCATED AT 250 WORDS)

Glutathione-dependent metabolism of trichloroethylene in isolated liver and kidney cells of rats and its role in mitochondrial and cellular toxicity

Metabolism of trichloroethylene (Tri) by the glutathione (GSH) conjugation pathway was studied in hepatocytes, renal cortical cells, and liver subcellular fractions from male Fischer 344 rats. Toxicity of Tri and some of its GSH- and cytochrome P450-dependent metabolites was then studied in isolated hepatocytes, kidney cells, and liver and kidney mitochondria to assess the relative role of these metabolites in toxicity. Tri metabolism to S-(1,2-dichlorovinyl)glutathione (DCVG), a nephrotoxic metabolite of Tri, was demonstrated in both isolated hepatocytes and kidney cells. This suggests that the first Tri bioactivation step that leads to nephrotoxicity in vivo occurs in both liver and kidney. Rates of DCVG formation in liver microsomes and cytosol were similar, although total activity was greater in cytosol. Only S-(1,2-dichlorovinyl)-L-cysteine (DCVC), but not Tri, DCVG, or the other oxidative metabolites examined (trichloroacetate, dichloroacetate, chloral hydrate, trichloroethanol, or oxalic acid) caused acute hepatotoxicity, whereas only DCVC and DCVG produced acute nephrotoxicity in isolated renal cortical cells. Tri and the metabolites examined, except trichloroacetate and DCVG, caused a loss of function of liver and kidney mitochondria. In liver mitochondria, DCVC produced the largest decrease in mitochondrial respiration, whereas Tri, trichloroethanol, and dichloroacetate were somewhat less toxic and chloral hydrate was the least toxic. In kidney mitochondria, in contrast, Tri, trichloroethanol, dichloroacetate, chloral hydrate, and DCVC caused similar decreases in mitochondrial respiration. These results suggest that, whereas both GSH conjugation and cytochrome P450-dependent metabolism of Tri generate mitochondrial toxicants, only the GSH-derived metabolites were cytotoxic.

Alteration of sulfation of glycoconjugates, but not sulfate transport and intracellular inorganic sulfate content in cystic fibrosis airway epithelial cells

The secreted and cell surface high molecular weight glyco-conjugates (HMG) generated by primary cultures of airway epithelial cells from cystic fibrosis (CF) patients are oversulfated. To determine whether this abnormality is maintained in transformed CF airway epithelial cells and whether differences in transport or intracellular accumulation of sulfate can explain this alteration, we assessed sulfate metabolism in paired CF and normal cell lines as well as primary cultures of CF and normal cells. Both 4-acetamido-4'-isothiocyanostilbene-2,2'-disulfonic acid-inhibitable and -resistant [35S]sulfate efflux and influx were identical for each pair of CF and normal cell lines. Furthermore, cell content of inorganic sulfate was not significantly different in CF and normal cells. However, compared with primary CF cells that oversulfate HMG transformed CF cells oversulfated cell surface HMG but not HMG released into culture medium. Our results suggest that plasma membrane sulfate transport is not altered in CF airway epithelial cells and the abnormal sulfation of HMG may be due to perturbation in intracellular sulfate activation or transfer of activated sulfate to HMG. The relationship of this abnormality to CF transmembrane conductance regulator mutations remains to be determined.

Melanin-like pigmentation of the duodenum

We report a case of brown-black pigmentation of the duodenum found in an elderly female during endoscopy for unrelated reasons. Melanin-like pigmentation of the duodenum is a rare endoscopic entity of uncertain etiology and significance. Various theories related to the etiology and pathogenesis, as well as histochemical and electron microscopic characteristics, are discussed.

Effects of ionic strength on the regulation of Na/H exchange and K-Cl cotransport in dog red blood cells

Dog red cell membranes contain two distinct volume-sensitive transporters: swelling-activated K-Cl cotransport and shrinkage-activated Na/H exchange. Cells were prepared with intracellular salt concentration and weight percentage of cell water (%cw) varied independently by transient permeabilization of the cell membrane to cations. The dependence of transporter-mediated Na and K influxes upon %cw and upon extracellular salt concentration (c(ext)) was measured in cells so prepared. It was found that the critical value of %cw at which transporters are activated, called the set point, is similar for the two transporters, and that the set points for the two transporters decrease similarly with increasing extracellular salt concentration. These findings suggest a common mechanism of regulation of these two transporters. Cellular Na, K, and Cl concentrations were measured as functions of %cw and c(ext). Using these data together with data from the literature for other solute concentrations, empirical expressions were developed to describe the dependence of the intracellular concentrations of all significant small molecule electrolytes, and therefore the intracellular ionic strength, upon %cw and c(ext). A mechanistic model for the dependence of the set point of an individual transporter upon intracellular ionic strength is proposed. According to this model, the set point represents a critical extent of association between the transporter and a postulated soluble regulatory protein, called regulator. Model functions are presented for the calculation of the thermodynamic activity of regulator, and hence extent of regulator-transporter association, as a function of total intracellular protein concentration (or %cw) and ionic strength. The experimentally observed dependence of set point %cw on c(ext) are simulated using these functions and the empirical expressions described above, together with reasonable but not uniquely determined values of model parameters.

Psychologic assessment in rheumatology

In rheumatology practice and applied research, there are numerous psychologic issues that merit special attention, including depression, helplessness, self-efficacy, and coping. A wide variety of measures are available for addressing these issues. The tests themselves must meet the psychometric criteria of reliability and validity. Psychologic tests must be administered under standardized conditions.

Comparison of transthecal digital block and traditional digital block for anesthesia of the finger

STUDY OBJECTIVE

To compare the newly described transthecal (TT) and traditional (TD) methods of digital block anesthesia with regard to length of time to achieve anesthesia and pain during infiltration.

DESIGN

Prospective, randomized, controlled, blinded study.

PARTICIPANTS

Healthy adult paid volunteers.

INTERVENTIONS

Each subject received a TT block on one hand and a TD block on the opposite hand. All blocks were performed by the same investigator and were rated by an evaluator who was blinded to the technique that was used. Time to loss of pin-prick sensation was measured, and the pain of the procedure was recorded by the subject on a 10-cm visual-analog scale.

RESULTS

A total of 162 blocks (81 TT and 81 TD) were performed in 31 different subjects. All blocks were successful. Mean time to anesthesia for TT block was 188 seconds compared with 152 seconds for the TD block (P < .01). Mean analog pain score was slightly higher for TT block than for TD block (1.7 versus 1.4, P = .02).

CONCLUSION

TT block is clinically equal to the TD method in terms of time to anesthesia and visual-analog pain score.

Creatine kinase is required for swelling-activated K-Cl cotransport in dog red blood cells

K-Cl cotransport in resealed dog red cell ghosts requires the incorporation of creatine phosphate before resealing; incorporation of ATP has no effect [Colclasure and Parker. Am. J. Physiol. 265 (Cell Physiol. 34): C1648-C1652, 1993]. A role for creatine kinase (CK) in swelling-activated K-Cl cotransport was investigated. 2,4-Dinitrofluorobenzene (DNFB), an inhibitor of CK, inhibited K-Cl cotransport in intact red blood cells and resealed ghosts from DNFB-treated cells. Incorporation of exogenous CK into ghosts of DNFB-treated cells restored K-Cl cotransport. Therefore DNFB inhibits CK and not the cotransporter. Inhibition of native CK in ghosts by DNFB and the incorporation of CK into the ghosts were demonstrated in electrophoretic gels. In a dose-response experiment, approximately 770 molecules CK/ghost restored 50% of control cotransport. Since creatine phosphate is a substrate only for CK, CK provides ATP to a site inaccessible to cytoplasmic ATP. The nature of this site and its role in K-Cl cotransport are uncertain, but an essential function for CK is established.

Regional pulmonary blood flow during rest, tilt, and exercise in unanesthetized dogs

We assessed the heterogeneity of regional pulmonary blood flow (PBFr), using radioactive microspheres in five unanesthetized dogs standing at rest (Rest), standing at a 45 degrees upward tilt (Tilt), and during moderate treadmill exercise (Exer). The excised lungs were cut into 1-cm3 pieces along transverse, horizontal, and longitudinal planes. Mean PBFr increased from 23.3 ml.min-1.g-1 at Rest to 57.4 ml.min-1.g-1 during Exer, but the relative dispersions were not statistically different between states (47.3-51.9%). A small but significant gravity-dependent gradient in PBFr of < or = 4.7%/cm (r2 < or = 0.118) as well as a PBFr decreasing radial gradient from the lung midpoint of < or = 7.2%/cm (r2 < or = 0.108) were present in all states. PBFr at Rest was highly correlated with those at Tilt (r2 = 0.773) and Exer (r2 = 0.888), and a variable PBFr gradient of < or = 2.5%/cm from base to apex was observed. Fractal dimensions calculated using relative dispersion as a function of aggregated sample size were not significantly different between states and were 1.132 (r2 = 0.987) at Rest, 1.121 (r2 = 0.973) at Tilt, and 1.149 (r2 = 0.986) during Exer. Thus, gravity and centripetal gradients consistently accounted for a maximal difference of only about twofold in PBFr and < 11% of overall PBFr heterogeneity in 1-cm3 samples. Recursive anatomic branching of pulmonary arteries and local mechanical factors apparently account for most of the blood flow heterogeneity in small pieces of lung.

Critical evaluation of clinical research

This focused review contains a suggested core of material that will help residents or practicing physiatrists critically review research papers published in the medical literature. Before accepting the results of a clinical trial, physiatrists must critique the experimental methods and study design carefully to decide whether to include these new ideas into their clinical practice. Medical research relies on statistical methodology, and statistics pervade the medical literature. This article begins with an introduction to rudimentary statistics. Fortunately, most studies depend on a rather small body of statistical concepts. The elements of experimental design--clinical trials, randomization, single-subject design, meta-analysis, epidemiological studies--are presented in a concise review. Finally, the elements of statistics and experimental design are integrated into a step-by-step method strategy for reading the medical literature.

Hyaluronan efflux from canine lung with increased hydrostatic pressure and saline loading

Although lymphatic washout of hyaluronan during lung hydration has been postulated to deplete lung interstitial hyaluronan content and thereby contribute to the decreased interstitial exclusion of albumin observed under these conditions, this hypothesis has not been directly tested. In anesthetized, ventilated mongrel dogs, a prenodal lung lymphatic was cannulated for measurement of lymph flow and hyaluronan concentration. Following baseline measurements, Pla was increased in four steps of 5 cm H2O in Group 1 or set to one pressure ranging between 6 and 32 cm H2O in Group 2. In Group 3, saline (15% body weight) was infused over 30 min and then Pla increased as in Group 2. Invariably, as lymph flow increased in Groups 1 through 3, lymph hyaluronan concentration and hyaluronan flux increased significantly (p < 0.05). In a separate control group, there were no changes in lymph flow, hyaluronan concentration, or hyaluronan flux. In Group 3, lung hyaluronan content at 5 h (0.76 +/- 0.08 mg/g dry weight) was not significantly less than that during baseline (0.88 +/- 0.05 mg/g dry weight), although total uronic acid content actually increased by 38% over the same time course. In contrast, in the control group, both lung hyaluronan and uronic acid content remained stable over the experimental period. From these data, approximately 2 to 3% of lung hyaluronan is predicted to leave the interstitium via lymphatic flux per day under baseline conditions. The daily turnover of interstitial hyaluronan by this route increased to 15 to 18% of total content when Pla was elevated and to 54% following saline infusion. Thus, lung hyaluronan can be rapidly mobilized with increased lymph flow.(ABSTRACT TRUNCATED AT 250 WORDS)