The leukointegrin alpha d/beta 2 (alpha d/CD18): specific changes in surface expression in patients on hemodialysis

Alpha d/CD18 is a newly discovered leukocyte adhesion molecule with sequence homology to CD11a, b and c of the beta 2 integrin family. Little is known about alpha d expression in vivo, particularly how it compares with the other beta 2 integrins. Previous studies have demonstrated that beta 2 integrin expression, particularly CD11b, is upregulated in vivo during hemodialysis (HD) with complement activating membranes. These changes may contribute to the immunologic abnormalities seen in HD patients. Given the well described changes of beta 2 integrins in these patients, we hypothesized that alpha d expression could also be altered by HD. Using flow cytometry with two specific antibodies to alpha d, alpha d expression in healthy adults (n = 16) was compared on macrophages (MO) > polymorphonuclear cells (PMNs) > lymphocytes (LY). Phorbol ester treatment of leukocytes in vitro significantly increased expression on MO and PMN, but not LY. Chronic HD patients at baseline (n = 15) had elevated (P < 0.05) alpha d mean channel fluorescence (MCF) on MOs, PMNs and LYs compared to normals. PMN alpha d MCF increased at 15 min into HD, but then returned to baseline levels at 180 min. Alpha d MCF for LYs decreased at 180 min, while MOs levels were unchanged. Alpha d expression is increased in chronic renal failure and further regulated by hemodialysis, but with unique characteristics compared to the other beta 2 integrins. Alpha d may be important in abnormal cell-cell contacts in renal failure.

Aquaporin-1: an osmoinducible water channel in cultured mIMCD-3 cells

The expressions of aquaporin-1 (AQP-1) in cultured mIMCD-3 cells were studied. There was no detectable AQP-1 in cells grown in serum-containing growth medium (SM, 297 +/- 2 mOsm/kg. H2O). When SM was supplemented with NaCl (406 +/- 2 mOsm/kg. H2O), cellular AQP-1 was induced. A further increase in medium osmolarity with NaCl (493 +/- 3 mOsm/kg. H2O) had conferred cells an 2.5 to 3-fold increase of AQP-1 expression over those grown in the 406 +/- 2 mOsm/kg. H2O medium. Moreover, AQP-1 was found to be translocated from cytosol to membrane. In addition, exposing the mIMCD-3 cells to vasopressin (AVP, 10(-8) M) and/or NaCl-supplemented serum-free media (496 +/- 3 mOsm/kg. H2O) for 6h did not render them to produce AQP-1. However, AQP-1 was induced after 24h of incubation, with an 1.5-fold additive effect by AVP. Our RT-PCR data had confirmed the NaCl inducibility and AVP synergism in AQP-1 expression at both mRNA and protein levels. This suggests a new role for cellular AQP-1 and AVP in overcoming osmotic stress in an in vitro system.

Role of IL-1 in renal ischemic reperfusion injury

Interleukin-1 (IL-1) is a central component of many acute inflammatory processes. Blocking IL-1 receptor (IL-1R) with IL-1R antagonist (IL-1Ra) has attenuated ischemic reperfusion injury in brain, heart, and liver models. However, the role of IL-1 in renal ischemic reperfusion injury (IRI) is not known. Therefore, the role of IL-1 in renal IRI was evaluated using the complementary approaches of IL-1R blockade in wild-type mice in addition to the study of renal IRI in IL-1R knockout (KO) mice. Ischemia was induced by bilateral renal pedicle clamping for 30 min. IL-1Ra was administered at 10 mg/kg every 4 h, high doses that have been protective in previous organ injury models in mice. IL-1R KO animals, previously characterized as insensitive to IL-1, had the absence of IL-1R1 confirmed by DNA blots. IL-1Ra, IL-1R KO, and control groups had similar elevations of blood urea nitrogen (114 +/- 13, 133 +/- 11, and 120 +/- 11 mg/dl) and serum creatinine (1.7 +/- 0.3, 2.1 +/- 0.2, and 1.6 +/- 0.3 mg/dl) 24 h after ischemia. Furthermore, acute tubular necrosis scores were also similar in IL-1Ra-treated mice (3.0 +/- 0.3), IL-1R KO mice (2.7 +/- 0.3), and control mice (3.1 +/- 0.2). However, both IL-1Ra and IL-1R KO groups, compared with control animals, developed significantly less infiltration of polymorphonuclear leukocytes per 10 high-power fields in postischemic renal tissue (1111 +/- 228 and 967 +/- 198 versus 1820 +/- 190, P < 0.05). In contrast to the comparable renal functions at 24 h, recovery of renal function was significantly accelerated in the IL-1R KO group compared with control at both 48 (P < 0.05) and 72 (P < 0.05) h. Recovery in the IL-1Ra group was similar to that in the control animals. These data demonstrate that IL-1 is unlikely to be beneficial in the recovery of renal function after ischemia and may play a deleterious role.

Effects of guanine nucleotides on glutamate-induced chemiluminescence in rat hippocampal slices submitted to hypoxia

Glutamate significantly increased levels of spontaneous chemiluminescence (CL) in rat hippocampal slices incubated under hypoxic conditions. Although it has been previously shown that guanine nucleotides (GN) displace glutamate from several of its receptors, in our study only GMP, as well as the glutamate antagonist MK-801, was able to reverse the increase in CL provoked by glutamate. On the other hand, not only GTP or Gpp(NH)p failed to reverse the action of glutamate, but they increased CL production like glutamate. This effect of GTP/Gpp(NH)p was also reversed by GMP. We concluded that, under neurotoxic conditions, GMP acted as an antagonist and GTP or Gpp(NH)p acted as agonists of glutamate. These results reinforced the evidence of the existence of extracellular site(s) for GN and indicated a possible role for GN in excitotoxicity.

Effect of potassium concentration in dialysate on total body potassium

OBJECTIVE

To investigate the effects of the presence/absence of potassium in the dialysate on total body potassium content in stable hemodialysis patients.

DESIGN

Randomized selection.

SETTING

Outpatient chronic hemodialysis unit at the James A. Haley VA Hospital in Tampa, Florida.

PATIENTS

Six adult hemodialysis patients (mean age 48 +/- 11.61 years, range 32-65 years) participated in this study. They were all males, four African-Americans and two Caucasians.

INTERVENTION

Subjects in a random order received dialysis using a dialysate containing no potassium for 3 months, followed by a 2 mEq/L of potassium for another 3 months. Total body potassium measurements and routine blood analysis were taken at baseline and after each three month period. All subjects received diet instruction pre and monthly on a 3 g/day potassium dietary restriction.

MAIN OUTCOME MEASURED

There were no significant differences in the amount of total body potassium concentration between the two different dialysates containing 0 or 2 mEq/L potassium. Mean values of serum albumin were significantly higher when the subjects were dialyzed on a 0 potassium bath.

CONCLUSION

The use of dialysate containing 0 or 2 mEq/L potassium concentration does not make a significant difference with regard to total body potassium concentration and maybe advantageous for the patients in terms of more freedom in nutritional intake as demonstrated by a significant increase in serum albumin when they were dialyzed on a 0 potassium bath.

Treatment of depression--newer pharmacotherapies

OBJECTIVES

Depressive disorders are persistent, recurring illnesses that impose enormous personal suffering on individuals and their families. Major depression alone is estimated as the fourth most important cause of worldwide loss in disability-adjusted life years and is likely to become the second most important within 20 years. A continued quest for more effective treatments has spawned newer antidepressants and herbal treatments, which have contributed to explosive growth in antidepressant prescribing, increasing pharmacy costs, and wider but sometimes confusing choices for clinicians and patients. This evidence report provides a comprehensive evaluation of the benefits and adverse effects of newer pharmacotherapies and herbal treatments for depressive disorders in adults and children.

SEARCH STRATEGY

Pertinent literature from 1980 to January 1998 was identified from a specialized registry of controlled trials, meta-analyses, and experts. The registry contained trials addressing depression that had been identified from multiple electronic bibliographic databases, hand searches of journals, and pharmaceutical companies. The search, which yielded 1,277 records, combined terms "depression," "depressive disorder," or "dysthymic disorder" with a list of 32 specific "newer" antidepressant and herbal treatments.

SELECTION CRITERIA

Randomized controlled trials were reviewed if they (1) were at least 6 weeks in duration; (2) compared a "newer" antidepressant with another antidepressant (newer or older), placebo, or psychosocial intervention; (3) involved participants with depressive disorders; and (4) had a clinical outcome. Two or more independent reviewers identified 315 trials that met these criteria.

DATA COLLECTION AND ANALYSIS

Two persons independently abstracted data from each trial. Data were synthesized descriptively, paying attention to participant and diagnostic descriptors, intervention characteristics, study designs and clinical outcomes. Some data were analyzed quantitatively using an empirical Bayes random-effects estimator method. Primary outcomes were response rate, total discontinuation rates (dropouts), and discontinuation rates due to adverse events. Response rates were defined as a 50 percent or greater improvement in symptoms as assessed by a depression symptoms rating scale or a rating of much or very much improved as assessed by a global assessment method.

MAIN RESULTS

There were 264 trials that evaluated antidepressants in patients (adults and children) with major depression. Of these, 81 compared newer agents with placebo, 150 newer with older agents, 32 newer agents with newer agents, and 1 newer agent with psychotherapy. There were 14 trials evaluating hypericum (St. John's wort), 27 trials each in primary care patients and older adults, 10 trials limited to patients with specific concomitant illnesses, 9 trials in patients with dysthymia, 3 trials each in patients with mixed anxiety depression and subsyndromal depression, 2 trials in adolescents, and 1 in the postpartum setting. Most trials were conducted in outpatients and examined only acute phase treatment of less than 12 weeks' duration. Newer antidepressants were more effective than placebo in treating major depression (risk ratio 1.6, 95% CI 1.5 to 1.7) and dysthymia (risk ratio 1.7, 95% CI 1.3 to 2.3). They were effective among older adults and in primary care patients. In general, there were no significant differences in efficacy among individual newer agents or between newer and older agents. Hypericum (St. John's wort) was more effective than placebo in treating mild to moderately severe depressive disorders (risk ratio 1.9, 95% CI 1.2 to 2.8). Whether hypericum (St. John's wort) is as effective as standard antidepressant agents given in adequate doses was not established. No significant differences were found between newer and older antidepressants in overall discontinuation rates. Selective serotonin reuptake inhibitors (SSRIs), reversi

Partial renal resistance to arginine vasopressin as an adaptation to high altitude living

BACKGROUND

The normal physiological response to high altitude (HA) is a decrease in total body water (TBW) and plasma and extracellular volume. The present investigation was designed to determine the mechanisms of the decrease in TBW with HA adaptation.

METHOD

There were 10 men from the Southern Colombian Andes (2600 m) in Pasto, Colombia, who were compared to age-matched men from sea level (SL), Tampa, FL, in the U.S., with respect to their TBW, ability to handle a water load and response to exogenous arginine vasopressin (AVP). Measurements included circulating AVP, atrial natriuretic peptides [atrial natriuretic factor (ANF) and vessel dilator], and urinary excretion of the AVP sensitive water channel, aquaporin-2 (AQP2).

RESULTS

The HA subjects had significantly (p < 0.01) lower TBW (29.37 +/- 0.98 vs 39.71 +/- 1.66 Kg), AQP2 excretion and vessel dilator circulating levels at baseline compared to SL subjects. ANF levels were not significantly different between the two groups. With water loading (20 ml.kg-1 in 15 min) there was a rapid increase in urine volume at 30 min with a decline thereafter in HA subjects while SL subjects had a gradual increment peaking at 120 min. There was a significant (p < 0.05) decrease in plasma AVP in the SL subjects within 30 min after the water load while the HA subjects had no significant decrease in AVP levels. Excretion of AQP2 decreased significantly after the water load only in the SL subjects. Administration of exogenous AVP increased AQP2 3- to 4-fold in the HA in comparison to SL subjects.

CONCLUSIONS

Present data demonstrate the following adaptations to HA: decrease in TBW, better ability to handle a water load despite high levels of AVP, a significant decrease in the circulation of vessel dilator, and diminished excretion of AQP2 water channel. These findings indicate an insensitivity of the collecting duct of HA subjects to the actions AVP. However, exogenous administration of AVP caused a marked excretion of AQP2.

Are the clinical effects of homeopathy placebo effects? A meta-analysis of placebo-controlled trials

BACKGROUND

Homeopathy seems scientifically implausible, but has widespread use. We aimed to assess whether the clinical effect reported in randomised controlled trials of homeopathic remedies is equivalent to that reported for placebo.

METHODS

We sought studies from computerised bibliographies and contracts with researchers, institutions, manufacturers, individual collectors, homeopathic conference proceedings, and books. We included all languages. Double-blind and/or randomised placebo-controlled trials of clinical conditions were considered. Our review of 185 trials identified 119 that met the inclusion criteria. 89 had adequate data for meta-analysis, and two sets of trial were used to assess reproducibility. Two reviewers assessed study quality with two scales and extracted data for information on clinical condition, homeopathy type, dilution, "remedy", population, and outcomes.

FINDINGS

The combined odds ratio for the 89 studies entered into the main meta-analysis was 2.45 (95% CI 2.05, 2.93) in favour of homeopathy. The odds ratio for the 26 good-quality studies was 1.66 (1.33, 2.08), and that corrected for publication bias was 1.78 (1.03, 3.10). Four studies on the effects of a single remedy on seasonal allergies had a pooled odds ratio for ocular symptoms at 4 weeks of 2.03 (1.51, 2.74). Five studies on postoperative ileus had a pooled mean effect-size-difference of -0.22 standard deviations (95% CI -0.36, -0.09) for flatus, and -0.18 SDs (-0.33, -0.03) for stool (both p < 0.05).

INTERPRETATION

The results of our meta-analysis are not compatible with the hypothesis that the clinical effects of homeopathy are completely due to placebo. However, we found insufficient evidence from these studies that homeopathy is clearly efficacious for any single clinical condition. Further research on homeopathy is warranted provided it is rigorous and systematic.

A woman with abdominal pain and a history of thromboses

A 39-year-old woman presented with progressively severe, sharp abdominal pain of three days' duration. The pain originated in the right lower quadrant of the abdomen and radiated to the back and suprapubic area. It worsened on ambulation and was associated with nausea and loose stools.

Anatomy of the cranioencephalic structures of the goat (Capra hircus L.) by imaging techniques: a computerized tomographic study

A topographic study of the cranioencephalic structure was carried out by computerized tomography on Canarian breed adult goats of medium size and weight, with similar cephalic parameters. In this way, transversal, sagittal and horizontal tomographic images were obtained. Identification of the observed anatomic structures represents the basis of this work from which applicable specie data are derived.

Gastric sarcoidosis

Sarcoidosis of the gastrointestinal tract is uncommon even though involvement of the liver, spleen, and adenopathy are becoming recognizable entities on computed tomography (CT). Involvement of the stomach, the most common site of sarcoidosis of the gastrointestinal tract, is usually associated with pulmonary disease. The radiologic appearances of gastric involvement are variable. Positive biopsies may be obtained in a radiologically normal stomach. Ulceration resembling peptic ulcer disease may occur, and mucosal enlargement may be minor, diffusely nodular, or significant enough to mimic Menetrier disease. In its most dramatic form, a linitis plastica appearance resembling scirrhous carcinoma has been reported.

Molecular modeling of (E)-1-alkyl-4(3)-[2-(1H-azolyl)vinyl]-pyridinium salts and evaluation of their behavior towards choline acetyltransferase

A new type of extended pi-system aza-analogue of (E)-4-[2-(1-naphthylvinyl)]-1-substituted pyridinium salts (NVP+) has been designed and its inhibitory activity towards choline acetyltransferase (ChAT) has been evaluated in vitro. Among the several examples of the title quaternary salts synthesized 2 and 3, the indolylvinylpyridinium salt 2e is the only one to show a very low ChAT inhibition. The molecular modeling study is highly illustrative of their behavior towards ChAT and interaction with the recognition site. Thus, several selected cations together with the reference NVP+ compound 1a were studied at the PM3 and AM1 levels respectively. At the global minima, all the compounds are planar, which, from the electron charge distribution, shows a degree of polarization similar to the NVP+ model compound 1a. However, the fitting of all optimized structures indicated that only the indole derivative 2e showed the same aromatic fragment orientation as 1a, which allows us to define a volume that is not accessible to ligands in the enzyme and consequently to a refined model of the choline acetyltransferase recognition site.

A naturally occurring mutant human epidermal growth factor receptor as a target for peptide vaccine immunotherapy of tumors

The type III EGF receptor (EGFRvIII) is the result of an in-frame deletion from nucleotides 275 to 1075 in the EGF receptor cDNA sequence creating a novel epitope at the fusion junction. This spontaneously occurring alteration is found in a high percentage of primary human brain, breast, lung and ovarian tumors. We have explored whether a peptide derived from the fusion junction could serve as the basis for an antitumor vaccine. Preimmunization of mice with this peptide substantially inhibited tumor formation by cells expressing EGFRvIII. Tumor cell inoculation followed by immunization could also enhance the regression of existing tumors. Antibody production was elicited in animals that was highly specific for the novel epitope and also a CTL response that was mediated by CD8+ T lymphocytes. The alteration present in EGFRvIII could serve as the basis for an antitumor vaccine with potentially wide application in humans.

Effect of guanine nucleotides on [3H]glutamate binding and on adenylate cyclase activity in rat brain membranes

GMP-PNP, a non-hydrolyzable analog of GTP binds tightly to G-protein in the presence of Mg2+, so that the binding is stable even after exhaustive washings. This property was exploited to prepare membrane samples of rat brain where G-protein GTP-binding sites were saturated with GMP-PNP. Experiments carried out with these membranes showed that GTP, GMP-PNP, GDP-S and GMP (1 mM) inhibit the sodium-independent [3H]glutamate binding by 30-40% [F(4,40) = 5.9; p < .001], whereas only GMP-PNP activates adenylate cyclase activity [F(6,42) = 3.56; p < .01]. The inhibition of sodium-independent [3H]glutamate binding occurred in the absence of Mg2+. These findings suggest that guanine nucleotides may inhibit glutamate binding and activate adenylate cyclase through distinct mechanisms by acting on different sites.

The treatment of chronic constipation in adults. A systematic review

OBJECTIVE

To evaluate whether laxatives and fiber therapies improve symptoms and bowel movement frequency in adults with chronic constipation.

DATA SOURCES

English language studies were identified from computerized MEDLINE (1966-1995). Biological Abstracts (1990-1995), and Micromedex searches; bibliographies; textbooks; laxative manufactures; and experts.

STUDY SELECTION

Randomized trials of laxative or fiber therapies lasting more than 1 week that evaluated clinical outcomes in adults with chronic constipation.

MEASUREMENTS AND MAIN RESULTS

Two independent reviewers appraised each trial's characteristics including methodologic quality. There were 36 trials involving 1,815 persons from a variety of settings including clinics, hospitals and nursing homes. Twenty-three trials were 1 month or less in duration. Several laxative and fiber preparations were evaluated. Twenty trials had a placebo, usual care, or discontinuation of laxative control group, and 16 directly compared different agents. Laxatives and fiber increased bowel movement frequency by an overall weighted average of 1.4 (95% confidence interval [CI] 1.1-1.8) bowel movements per week. Fiber and bulk laxatives decreased abdominal pain and improved stool consistency compared with placebo. Most nonbulk laxative data concerning abdominal pain and stool consistency were inconclusive, though cisapride, lactulose, and lactitol improved consistency. Data concerning superiority of various treatments were inconclusive. No severe side effects for any of the therapies were reported.

CONCLUSIONS

Both fiber and laxatives modestly improved bowel movement frequency in adults with chronic constipation. There was inadequate evidence to establish whether fiber was superior to laxatives or one laxative class was superior to another.

[Pigmented villonodular synovitis of the wrist. Apropos of a case]

The authors presented a case of pigmented villonodular synovitis of the wrist with extrinsic bony defects on opposing articular surfaces, seen after two recurrences following excision surgery. They performed a total synovectomy followed by curettage and autogenous bone grafting of the carpal and radiocubital bone lesions. Four years after the procedure, the patient-a woman aged 44-was symptom-free and there was no objectivable evidence of recurrence. Pigmented villonodular synovitis (PVNS) is an uncommon, benign, chronic process that causes synovial proliferation. Its etiology is unknown. The majority of patients is young to middle-aged adults. Especially the knee but other joints are involved including the hip, ankle, wrist, hand, and foot. Both soft tissue and bone abnormalities occur in PVNS. Magnetic resonance imaging (MRI) shows a heterogenous synovial mass with intermediate and low signal intensity areas on T1 and T2-weighted images, consistent with hemosiderin deposition. Computed tomography defines clearly the extrinsic bone erosions and excavations, which usually exhibit a sclerotic margin, produced by intraosseous invasion of the expanding synovia. After excision recurrence is common, leading eventually to arthrodesis, arthroplasty and even radiation therapy. The etiology of PVNS is controversial. First approach is conservative surgical treatment with total synovectomy and curettage of the osteolytic foyers. Bone grafts are employed for filling the sites of osteolysis. The sensitivity of MRI permits early detection of the process and may obviate the need for radical management options in PVNS.

St John's wort for depression--an overview and meta-analysis of randomised clinical trials

OBJECTIVE

To investigate if extracts of Hypericum perforatum (St John's wort) are more effective than placebo in the treatment of depression, are as effective as standard antidepressive treatment, and have fewer side effects than standard antidepressant drugs.

DESIGN

Systematic review and meta-analysis of trials revealed by searches.

TRIALS

23 randomised trials including a total of 1757 outpatients with mainly mild or moderately severe depressive disorders: 15 (14 testing single preparations and one a combination with other plant extracts) were placebo controlled, and eight (six testing single preparations and two combinations) compared hypericum with another drug treatment.

MAIN OUTCOME MEASURES

A pooled estimate of the responder rate ratio (responder rate in treatment group/responder rate in control group), and numbers of patients reporting and dropping out for side effects.

RESULTS

Hypericum extracts were significantly superior to placebo (ratio = 2.67; 95% confidence interval 1.78 to 4.01) and similarly effective as standard antidepressants (single preparations 1.10; 0.93 to 1.31, combinations 1.52; 0.78 to 2.94). There were two (0.8%) drop outs for side effects with hypericum and seven (3.0%) with standard antidepressant drugs. Side effects occurred in 50 (19.8%) patients on hypericum and 84 (52.8%) patients on standard antidepressants.

CONCLUSION

There is evidence that extracts of hypericum are more effective than placebo for the treatment of mild to moderately severe depressive disorders. Further studies comparing extracts with standard antidepressants in well defined groups of patients and comparing different extracts and doses are needed.

Renal ischemic-reperfusion injury in L-selectin-deficient mice

L-selectin on leukocyte surfaces mediates cell rolling on endothelium. L-selectin blockade with antibodies attenuated ischemic-reperfusion injury (IRI) in heart and skeletal muscle, but its role in renal IRI is unknown. We evaluated the role of L-selectin in renal IRI using L-selectin-deficient mice. Neutrophil migration to chemically inflamed peritoneum was reduced by 47% (P < 0.01) in L-selectin-deficient mice. Ischemia was induced by bilateral renal pedicle clamping for 30 min. Control and L-selectin groups had similar elevations of serum creatinine (1.8 +/- 0.3 vs. 1.7 +/- 0.2 mg/dl) and blood urea nitrogen (111 +/- 17 vs. 128 +/- 12 mg/dl) 24 h postischemia. Pathological assessment showed comparable degrees of tubular necrosis at 24 h. The postischemic increase in peritubular neutrophils per 10 high-power field was similar in control and L-selectin-deficient groups at 4 (28 +/- 10 vs. 22 +/- 5), 12 (245 +/- 80 vs. 236 +/- 78), and 24 h (130 +/- 12 vs. 156 +/- 18). These data argue against a significant role for L-selectin in renal IRI. Patho-physiological roles of L-selectin in vivo appear to be more complex than in vitro data would suggest.

Multiple primary malignancies in a renal transplant patient

Organ transplantation and the use of immunosuppressive therapy has been associated with an increased incidence of malignancy. We report the case of a long-term renal transplant recipient who developed concomitant skin cancers, non-Hodgkin's lymphoma, and malignant fibrous histiocytoma. The development of three seemingly unrelated cancers in the same patient illustrates the favorable host environment in transplant patients for the development of malignancies.

Health care access among Mexican Americans with different health insurance coverage

This study describes the rates of health care access among Mexican Americans with different health insurance coverage. An interview questionnaire was used to collect information regarding sociodemographics, perceived health status, health insurance coverage, and sources of health care from a random sample of 501 Mexican Americans from San Antonio, Texas. Health care access was determined more by having health insurance coverage than by health care needs. Poor Mexican Americans with health insurance had higher health care access rates than did poor Mexican Americans without health insurance. Health care access may improve health care outcomes, but more comprehensive community-based campaigns to promote health and better use of health services in underprivileged populations should be developed.

Alterations in soluble intercellular adhesion molecule-1 and vascular cell adhesion molecule-1 in hemodialysis patients

Hemodialysis (HD) patients can develop acute reactions during treatment as well as increased long-term susceptibility to infections and malignancies. Abnormalities in leukocyte adhesion may contribute to these processes. Recently, serum levels of soluble adhesion molecules have been detected in circulating blood of normal subjects and in patients with chronic renal failure. We studied the effects of a single dialysis session with new cuprophane membrane on the soluble (s) form of intracellular adhesion molecule-1 (ICAM-1) and vascular cell adhesion molecule-1 (VCAM-1), two adhesion molecules with a variety of immunologic roles. Significant elevations in both sICAM-1 (523 +/- 61 v 304 +/- 45 [SEM] ng/mL, P < 0.05) and sVCAM-1 (2,055 +/- 270 v 1,189 +/- 149 ng/mL, P < 0.05) were observed in HD patients at baseline compared with controls. Both sICAM-1 and sVCAM-1 levels decreased after a 3-hour HD session (P < 0.001). Early in HD, sICAM-1 levels, though lower than predialysis, were elevated in the exit line of the dialyzer compared with entrance (339 +/- 64 v 259 +/- 53 ng/mL, P < 0.001), whereas sVCAM-1 was decreased on the exit line compared with entrance (639 +/- 90 v 932 +/- 92 ng/mL, P < 0.001). Because ICAM-1 and VCAM-1 are important for many leukocyte functions, alterations in serum levels of sICAM-1 and sVCAM-1 may play a role in the immunologic consequences of uremia and HD treatment.

Hypoxic effects on the expression of mineralocorticoid and glucocorticoid receptors in human renal cortex epithelial cells

The effects of both mild and severe hypoxic conditions on the expression of mineralocorticoid receptor (MR) and glucocorticoid receptor (GR) in the primary human renal cortex epithelial cells (RCEC) were investigated. Slot blot analyses were performed with human beta-actin cDNA and the cDNA probes for unique regions of MR and GR. The steady-state mRNA level of the house-keeping beta-actin gene remains the same in RCEC under either normoxic or hypoxic conditions. However, there was a 45% reduction in MR expression and a 30% increase in GR expression, under mild hypoxic condition (15% O2) over 3 days. Furthermore, cells subjected to a severe hypoxic condition (0.5% O2) for 24 hours exerted a 22% reduction in MR expression and a 64% increase in GR expression. Changes in MR and GR expression may, in part, explain the physiological changes in adrenal cortical function observed in hypoxic conditions.

Alpha-V/beta-3 and alpha-V/beta-5 integrin distribution in neoplastic kidney

Integrins are transmembrane glycoproteins that mediate cell-cell and cell-matrix interactions. Altered integrin expression may contribute to tumor progression, invasiveness and metastases. The alpha-V/beta-3 (alpha v beta 3; osteopontin/ vitronectin receptor) has recently been implicated in neovascularization and tumor-induced angiogenesis. alpha v-Subunit also associates with beta 5 to form an alpha v beta 5-complex, another vitronectin receptor. We studied tissue distribution of alpha v beta 3-and alpha v beta 5-integrins, as well as alpha 1- and beta 1-subunits in nephrectomy samples from 7 subjects with localized renal cell carcinoma. Grossly and histologically uninvolved regions ('normal') from the same nephrectomy specimens were used for comparison. Integrin expression was studied with specific monoclonal antibodies and the immunoperoxidase technique. alpha v beta 3 was expressed in the glomerular epithelial cells, Bowman's capsule, vascular endothelium, and weakly in tubular epithelial cells. alpha v beta 5 had a similar distribution except for minimal expression on vascular endothelium. alpha 1-Expression was observed in mesangium and but weakly in Bowman's capsule. beta 1-Expression was seen in glomerular epithelial cells, Bowman's capsule, vascular epithelium and tubular epithelial cells. Unlike in 'normals', neoplastic expression was more heterogeneous alpha v beta 3 was expressed in tumor cells in 4/7 cases, vascular endothelium in 6/6, and in stroma in 4/7. alpha v beta 5 was weakly expressed in tumor cells in 4/5, vascular endothelium in 5/5, and stroma in 4/5 cases. alpha 1-Expression was seen in tumor cells in 3/7, vascular endothelium in 4/7 and in stroma in 7/7 cases. beta 1-Expression was seen in tumor cells in 7/7 cases, vascular endothelium in 7/7, and in stroma in 4/7 cases. This study delineates the pattern of expression of the alpha v beta 3-and alpha v beta 5-integrins in 'normal' and neoplastic human kidney. Variations in alpha v beta 3-and alpha v beta 5-integrin expression may play a role in normal and neoplastic processes of the kidney.

The Effect of Hemodialysis on the Expression of Platelet Glycoproteins Ib, IIb/IIIa and P-Selectin

To determine the effect of hemodialysis on expression of platelet receptors in patients with chronic renal failure.

DESIGN

Blood sampling performed in chronic HD patients prior to the dialysis session, then 15 and 180 minutes into HD. Both dialysis machine inlet and outlet samples were taken at 15 minutes. Control subjects had a single blood sample taken.

PATIENTS

Thirteen adult males on chronic hemodialysis and 20 age and sex matched healthy controls.

MEASUREMENTS

Flow-cytometric analysis of platelet GP-Ib, GP-IIb/IIIa, and P-selectin. Plasma vWF multimers were analyzed by SDS-polyacrylamide gel electrophoresis and immunoblotting.

RESULTS

Mean channel fluorescence (MCF) for GP lb was significantly (P < 0.05) decreased in pre-dialysis patients compared to controls and decreased further 3 hours into the dialysis session compared to the start of the dialysis treatment (P < 0.01). MCF for GP IIb/IIIa between predialysis patients and controls was similar, but decreased after a single dialysis session (P < 0.01). MCF for P-selectin on platelets was similar in patients and controls, but fewer platelets from the patients expressed P-selectin compared to controls (P < 0.05). Qualitative multimeric analysis of the vWF in patients, pre- and post-HD was unchanged.

CONCLUSIONS

Alterations in platelet surface expression of GPIb, GPIIb/IIIa, and P-selectin may, partially contribute to the changes in platelet function seen in patients on hemodialysis. It is unlikely that alterations in the surface expression of these receptors alone can adequately account for the complex platelet and hemostatic changes associated with uremia and the HD procedure.

Integrin expression on cell adhesion function and up-regulation of P125FAK and paxillin in metastatic renal carcinoma cells

Integrins from normal human renal cortex epithelial cells (RCEC) and from four renal carcinoma lines (metastatic Caki-1, non-metastatic Caki-2, metastatic ACHN, and non-metastatic 769-P) were compared by immunoprecipitation with specific anti-integrin antibodies. Integrin alpha 2 was present in normal RCEC, but absent in all four tumor lines. There was a 2.0-3.0 fold decrease of alpha 3 and beta 1 in localized tumor lines, and a further 5.0-7.0 fold decrease in metastatic lines over their expression in normal renal cells. No alpha V was detected in Caki-1 cells. The greatest adhesion of all cells occurred in the presence of a stimulatory anti-alpha 3 antibody, mediated by specific matrix proteins employed as substrates, while anti-beta 1 treatment dramatically inhibited cell attachment on collagen IV, plasma fibronectin, laminin and merosin substrates. In addition, the mRNA expression of focal adhesion kinase (p125FAK) and paxillin were up-regulated (2.0-2.5 fold increase) in the metastatic Caki-1 cells over normal RCEC. The alteration of integrin subunits alpha 2, alpha 3, alpha V, beta 1, as well as p125FAK and paxillin may contribute to the pathogenicity and/or metastatic propensity of renal epithelial tumors. The up-regulation of paxillin independently or in concert with p125FAK as shown in this study indicates its significant role as a potential marker of metastasis in renal carcinoma cells.

[Histochemical and morphometric study of the fibrillar population of the diaphragm muscle. II. Cow and pig]

M-ATPase techniques, at different pH levels prior to incubation, as well as metabolic procedures (alpha-MGPDH and NADH-TR), were used to determine the fibre-type content of the lumbar and costal portions in the bovine and porcine diaphragm. The fibre samples were exposed to image analysis in order to evaluate both the morphometrical and statistical values. On the basis of staining reactions, the fibre types IA, IB and IIC were found in the lumbar portion of the bovine diaphragm; in the costal portion of the same diaphragm, IA, IB, IIA and IIC fibre types were observed. With regard to the porcine diaphragm, the I, IIA, IIB, IIC fibre types were present in both portions of the muscle. Further morphometrical and statistical data concerning all the fibre types are obtained and discussed.

Frequent expression of a mutant epidermal growth factor receptor in multiple human tumors

The epidermal growth factor receptor has received much interest as a target for various antineoplastic agents, but a complication is that many normal tissues also express this receptor. We have previously identified in human glial tumors an 801-bp in-frame deletion within the epidermal growth factor receptor gene that created a novel epitope at the junction. By using Western blot assays with a mutant-specific antibody as a rapid and sensitive means for detecting this alteration in primary human tumors, it was found that 57% (26 of 46) of high-grade and 86% (6 of 7) of low-grade glial tumors, but not normal brain, express this protein. This altered receptor was also present in 66% (4 of 6) of pediatric gliomas and 86% (6 of 7) of medulloblastomas, 78% (21 of 27) of breast carcinomas, and 73% (24 of 32) of ovarian carcinomas. The fact that this receptor is frequently found in tumors but not in normal tissue makes it an attractive candidate for various antitumor strategies.

Salt excretory capacity in natives adapted to moderate high altitude living after acute mobilization to sea level

The sodium excretory capacity of six normal subjects born and raised at moderately high altitude (2600 m) was evaluated at high altitude (HA), and after acute mobilization to sea level (SL). The ability of these individuals to respond to an acute salt load was evaluated by infusing a volume of 100 ml.m-2 body surface area (BSA) of 5% sodium chloride solution over a 30-min time period in both experimental conditions. HA natives were able to excrete a significantly greater salt load at HA than at SL (41.8% vs. 31.6%, respectively, p < 0.05) in 3 h. No changes in plasma atrial natriuretic factor (ANF) concentration were found in either experimental condition. Despite an increase in serum osmolality, no vasopressin (AVP) response was noted either at HA or SL. No correlation between serum AVP levels and urine c-AMP concentrations was found. The enhanced excretory response to a salt load at HA was not explained by the measured hormonal changes. The lack of AVP response to increased serum osmolality, both at HA and SL, in high altitude adapted subjects is presently unexplainable.

Alterations in soluble and leukocyte surface L-selectin (CD 62L) in hemodialysis patients

Hemodialysis (HD) patients can develop acute reactions during treatment as well as increased long-term susceptibility to infections and malignancy. Leukocyte-membrane interactions may contribute to these processes. The effects of a single HD session on L-selectin, a leukocyte adhesion molecule for endothelium, were examined. Serum levels of soluble L-selectin were measured in 23 patients by enzyme-linked immunosorbent assay before and after a 3-h dialysis session. There was a statistically significant increase in soluble L-selectin from 1.36 +/- 0.12 (SE) to 1.57 +/- 0.18 micrograms/mL (P < 0.001). An increase in shed L-selectin was observed for the "venous" compared with the "arterial" part of the dialyser (P < 0.01) 15 min into HD. Soluble L-selectin levels were found to remain increased at 3 h after treatment. Leukocyte-bound L-selectin and CD11b was examined by the use of flow cytometry. Neutrophil L-selectin decreased to 69 +/- 7% at 15 min (P < 0.01) and then rebounded to 98 +/- 7% at 180 min. Monocyte and lymphocyte L-selectin did not decrease. Because L-selectin is important for leukocyte attachment to endothelium at sites of inflammation, alterations of shed L-selectin and cell-surface L-selectin levels may play a role in the immunologic consequences of HD treatment.

Effect of haemoglobin and endogenous erythropoietin on hypothalamic-pituitary thyroidal and gonadal secretion: an analysis of anaemic (high EPO) and polycythaemic (low EPO) patients

OBJECTIVE

Correction of anaemia with recombinant human erythropoietin (rHu-EPO) improves the responsiveness of thyroidal and gonadal axes to exogenous TRH and GnRH in chronic haemodialysis patients, but the mechanisms remain to be fully elucidated. In order to assess the influences of endogenous erythropoietin on the hypothalamo-hypophyseal thyroidal and gonadal axes, we studied the response of polycythaemic and anaemic patients, in comparison to normal controls, after the administration of exogenous TRH and GnRH.

DESIGN

Exogenous hypothalamic factors, 500 micrograms TRH and 100 micrograms GnRH, were administered as a bolus and blood samples were obtained over a 3-hour period at 30, 60, 90, 120 and 180 minutes.

PATIENTS

Five male polycythaemic patients (low EPO), three male anaemic patients (high EPO) and six normal age and sex matched controls were studied.

MEASUREMENTS

Blood samples were centrifuged immediately and the serum was stored at -20 degrees C until assayed for total T4, free T4, free T3, TSH, prolactin, growth hormone (TRH test), and FSH, LH, testosterone (GnRH test). Haematological parameters and biochemical profiles were also measured.

RESULTS

After TRH administration, both patient groups showed a normal TSH response; however, their free T4 and free T3 secretion was blunted compared to controls. Normal basal PRL levels increased in an exaggerated fashion, whereas, when compared to chronic renal failure patients on chronic haemodialysis, we did not see a paradoxical GH response or a basal GH increase in these 5 patients. GnRH administration in the study groups elicited a normalization in the LH response without an increase in testosterone levels; however, an exaggerated FSH response was found in the polycythaemic patients (low EPO).

CONCLUSIONS

Thus by investigating the role of low endogenous EPO levels in non-anaemic and anaemic patients with high EPO levels, our study suggests that the underlying chronic disease state may be the major contributing factor in the regulation of the hypothalamo-hypophyseal thyroid and gonadal axes, rather than the EPO levels.

The effects of high altitude on hypothalamic-pituitary secretory dynamics in men

OBJECTIVE

Individuals adapted to high altitude (HA) have abnormalities in endocrine function and specifically in the pituitary-thyroid axis and aldosterone regulation. In this study we assessed hypothalamic-pituitary function in men adapted to high altitude living using exogenous administration of synthetic hypothalamic hormones.

DESIGN

Growth hormone releasing hormone (Geref 1-29) 1 microgram/kg, TRH 500 micrograms, GHRH 100 micrograms and ovine corticotrophin releasing hormone (oCRH) 1 microgram/kg were simultaneously administered intravenously to two groups of men: 12 born and raised in the city of Pasto, Colombia, South America, located at an altitude of 2600 m in the southern Colombian Andes (HA group) and 10 men living at sea level (SL) in Tampa, Florida.

MEASUREMENTS

The following hormones were measured: GH, IGF-I, TSH, T4, free T4, free T3, PRL, ACTH, beta-endorphin and cortisol. IGF binding protein-3 (IGFBP-3) and cortisol binding globulin (CBG) were also measured.

RESULTS

GH response to GHRH in HA men was exaggerated compared to SL men, and IGF-I concentration was also significantly increased in the presence of normal levels of IGFBP-3. No differences in TSH or PRL responses were found following TRH. HA men had lower basal total T4 levels, but higher free T4 and free T3 concentrations. The basal ACTH concentrations in the HA men were significantly lower than SL, although the response to oCRH was still present. beta-Endorphin basal levels were similar at HA and SL but the response to oCRH at HA was blunted. At HA, basal cortisol levels as well as CBG were elevated compared to SL and, in contrast to SL, did not increase significantly after endogenous ACTH secretion.

CONCLUSIONS

This study is the first description of exaggerated GH response to the administration of GHRH in HA men and also of a significant increase in IGF-I concentration in the same subjects in the presence of normal levels of IGFBP-3. An altered hypothalamic-pituitary response was found in HA men after administration of oCRH characterized by a significantly lower basal ACTH concentration at HA, although the response to oCRH was present but the beta-endorphin response to oCRH was blunted. At HA, basal cortisol levels, as well as CBG, were elevated and the cortisol levels did not significantly increase after endogenous ACTH secretion. We have characterized the differences in hypothalamic-pituitary dynamics after the administration of TRH, GnRH and oCRH in HA men comparing their response to age/sex matched SL men.

Case-finding instruments for depression in primary care settings

OBJECTIVE

To evaluate the usefulness of case-finding instruments for identifying patients with major depression in primary care settings.

DATA SOURCES

A MEDLINE search of the English-language medical literature; bibliographies of selected papers; and experts.

STUDY SELECTION

Studies that were done in primary care settings with unselected patients and that compared case-finding instruments with accepted diagnostic criterion standards for major depression were selected.

DATA SYNTHESIS

9 case-finding instruments were assessed in 18 studies. More than 15,000 patients received screening with a case-finding instrument; approximately 5300 of these received criterion standard assessment. Case-finding instruments ranged in length from 2 to 28 questions. Average administration times ranged from less than 2 minutes to 6 minutes. Sensitivities and specificities for detecting major depression ranged from 67% to 99% and from 40% to 95%, respectively. No significant differences between instruments were found. Overall sensitivity was 84% (95% CI, 79% to 89%); overall specificity was 72% (CI, 67% to 77%). If a case-finding instrument were administered to 100 primary care patients with a 5% prevalence of major depression, the clinician could expect that 31 patients would screen positive, that 4 of the 31 would have major depression, and that 1 patient with major depression would not be identified.

CONCLUSIONS

Several instruments with reasonable operating characteristics are available to help primary care clinicians identify patients with major depression. Because the operating characteristics of these instruments are similar, selection of a particular instrument should depend on issues such as feasibility, administration and scoring times, and the instruments' ability to serve additional purposes, such as monitoring severity or response to therapy.

Antibodies to ICAM-1 protect kidneys in severe ischemic reperfusion injury

ICAM-1 has been implicated in the pathophysiology of ischemic-reperfusion injury in a number of organs, but its role in mediating severe ischemic-reperfusion injury in the kidney has not been extensively studied. Uninephrectomized Sprague Dawley rats were pretreated with either control monoclonal antibody (mAb) or mAb to ICAM-1 and subjected to 60 min of renal artery occlusion. The serum creatinine, complete blood count and kidney histo-pathological damage scores (PDS) (Scale:0-4) were assessed prior to and 24 hours after ischemia. Mean serum creatinine (mg/dl) 24 hours after ischemia was significantly decreased in the anti-ICAM-1 group (1.38 +/- 0.23, p < 0.001) compared to control (2.87 +/- 0.34). PDS was also reduced in anti-ICAM-1 (2.55 +/- 0.20, p < 0.05) group compared to control (3.35 +/- 0.30). These data demonstrate that blocking ICAM-1 significantly mitigates severe ischemic acute renal failure, findings which may lead to improved therapy for this condition.

Transmission of HIV in dialysis centre

In August, 1993, 13 dialysis patients at one dialysis centre in Colombia, South America, were found to be HIV positive, and this prompted an epidemiological investigation. We carried out a cohort study of all dialysis centre patients during January, 1992 to December, 1993 (epidemic period) to determine risk factors for HIV seroconversion. Haemodialysis and medical records were reviewed, dialysis centre staff and surviving patients were interviewed, and dialysis practices were observed. Stored sera from all dialysis centre patients were tested for HIV antibody. 12 (52%) of 23 patients tested positive for HIV antibody by enzyme immunoassay and western blot during the epidemic period. Of the 23 tested, 9 (39%) converted from HIV antibody negative to positive (seroconverters) and 10 (44%) remained HIV negative (seronegatives). The HIV seroconversion rate was higher among patients dialysed at the centre while a new patient, who was HIV seropositive, was dialysed there (90% vs 0%; p < 0.01), or when the dialysis centre reprocessed access needles, dialysers, and bloodlines (60% vs 0%). While 2 of 9 HIV seroconverters had had sex with prostitutes, none had received unscreened blood products or had other HIV risk factors. No surgical or dental procedures were associated with HIV seroconversion. Dialysers were reprocessed separately with 5% formaldehyde and were labelled for use on the same patient. Access needles were reprocessed by soaking them in a common container with a low-level disinfectant, benzalkonium chloride; 4 pairs of needles were placed in one pan creating the potential for cross-contamination or use of one patient's needles on another patient. HIV transmission at the dialysis centre was confirmed. Improperly reprocessed patient-care equipment, most probably access needles, is the likely mechanism of transmission. This outbreak was discovered by accident and similar transmission may be occurring in many other countries where low-level disinfectants are used to sterilise critical patient-care equipment.

Susceptibility to high-altitude pulmonary edema in Madison and Hilltop rats. I. Ventilation and fluid balance

The pathogenesis of high-altitude pulmonary edema (HAPE) is not well understood. Ventilation and fluid-handling abnormalities at high altitude (HA) may play a role in HAPE. Because ventilatory and cardiopulmonary responses to chronic HA exposure in the Hilltop (H) strain of Sprague-Dawley rat are different from those in the Madison (M) strain, it was hypothesized that these strains would have different susceptibilities to developing HAPE. M and H rats were studied at sea level (SL) and in a hypobaric chamber after 9 and 12 h at a simulated altitude of 24,000 ft (barometric pressure = 295 mmHg) and 1, 12, and 24 h at a simulated altitude of 18,000 ft (barometric pressure = 380 mmHg). Both strains developed HAPE, but the M rat was more susceptible to HAPE, as demonstrated by a higher mortality rate from hemorrhagic pulmonary edema after 9 h at 24,000 ft and an earlier increase in lung water after exposure to 18,000 ft. Minute ventilation was similar in both strains at HA, but arterial PO2 was significantly higher in the M rat. Both strains had a significant decrease in fluid intake and negative sensible water balance at HA. No changes in plasma renin activity, aldosterone concentrations, antidiuretic hormone levels, and atrial natriuretic peptide levels were found at HA. The increased susceptibility of the M rat to HAPE is therefore not explained by ventilation or fluid-handling abnormalities.

CT-guided renal biopsy using a coaxial technique and an automated biopsy gun

In this series, 35 patients with medical renal disease had renal biopsy guided by computed tomography (CT). Biopsies were done by a coaxial technique in which a thin-walled 16 guage guide needle is placed adjacent to the renal capsule of the lower pole. An 18 gauge cutting needle is then placed through the guide needle, and multiple samples (2 to 4) are obtained with an automated biopsy gun. Adequacy of specimens is immediately checked in the CT suite using low-power microscopy. Specimens are submitted for light, electron, and immunofluorescence microscopy. Adequate tissue for definite diagnosis was obtained in 33 of the 35 patients (94%). One patient had moderate postbiopsy bleeding and was hospitalized. There were no major complications. CT-guided renal biopsy using a coaxial technique and automated biopsy gun is an effective means of obtaining tissue for the evaluation of medical renal disease.

VLA-4 and its ligands: relevance to kidney diseases

Alterations in cellular immunity have been implicated in many kidney diseases. The role of the adhesion molecule VLA-4 and its known ligands VCAM-1 and CS-1 have just begun to be evaluated in association with kidney diseases. VCAM-1 in human kidney is normally expressed in the Bowman's capsule, in the proximal renal tubule, and in the vascular endothelium. Up-regulation of VCAM-1 expression is seen in many different forms of glomerulonephritis as well as in a mouse model of lupus nephritis. Up-regulation of VCAM-1 expression is observed in the renal allograft with acute cellular rejection, and correlates with areas of leukocyte infiltration and vascular inflammation. CS-1 may also be up-regulated in the rejecting kidney. Animal studies on cardiac transplantation demonstrate that blockade of VLA-4 or VCAM-1 can attenuate transplant rejection. Hemodialysis patients, known to have a cellular immunodeficiency, have increased levels of soluble VCAM-1 in their serum. There is increasing evidence that there are alterations in VLA-4, VCAM-1 and CS-1 in association with kidney diseases. Further studies will be required to delineate the role of these molecules in the immunopathogenesis of select kidney diseases and the possibility of intervening in these adhesion pathways to ameliorate clinical syndromes.

Diuretic effect of acute hypoxia in humans: relationship to hypoxic ventilatory responsiveness and renal hormones

Acute hypoxia causes increased sodium and water excretion. Animal studies suggest that this renal response is largely driven by direct peripheral arterial chemoreceptor stimulation, independent of accompanying changes in ventilation and acid-base status. Whether the diuresis and natriuresis observed in humans made acutely hypoxic are caused by peripheral chemoreceptor stimulation is not known, but, if so, we hypothesized that people with a high ventilatory response to hypoxia (high peripheral chemosensitivity) should have greater diuresis and natriuresis than those with a low ventilatory response to hypoxia. The isocapnic hypoxic ventilatory response (HVR) of 16 subjects on a fixed sodium intake was measured, as were their urinary volume and sodium and bicarbonate losses during 6 h of breathing air (in a normobaric environmental chamber) and, on the subsequent day, 12% O2. The isocapnic HVR correlated positively with hypoxic diuresis (r = 0.87) and natriuresis (r = 0.76). In contrast, the isocapnic HVR did not correlate with bicarbonate excretion, despite the expected respiratory alkalosis of acute hypoxia. The magnitude of diuresis and natriuresis with hypoxia did not correlate with changes in circulating aldosterone, renin, atrial natriuretic peptide, vasopressin, or a digoxin-like immunoreactive substance. These findings are compatible with a role of the peripheral arterial chemoreceptors in mediating the renal response to hypoxia in humans. The efferent pathway remains unknown.

Guanine nucleotides inhibit the stimulation of GFAP phosphorylation by glutamate

Phosphorylation of the astrocytic marker protein glial fibrillary acidic protein (GFAP) in hippocampal slices from immature rats is stimulated by glutamate agonists via a metabotropic receptor. In this study we investigated the modulation of this stimulation by guanine nucleotides. Recent work has shown that guanine nucleotides inhibit the binding of kainate to its receptors in a manner independent of G proteins. Gpp(NH)p, GDP-beta-S and GMP inhibited by approximately 50% the stimulation of GFAP phosphorylation by glutamate or 1S,3R-ACPD. In the case of glutamate and Gpp(NH)p it was shown that the inhibition was dose dependent. These results indicate that guanine nucleotides can inhibit glutamate-stimulated phosphorylation responses by interaction with a cell surface metabotropic receptor.

Abdominal manifestations of sarcoidosis. CT appearances

Sarcoidosis frequently involves the abdomen, although imaging studies often fail to demonstrate disease. The most common computed tomography (CT) findings in abdominal sarcoidosis are hepatosplenomegaly and retroperitoneal adenopathy, followed by focal low-attenuation lesions of the liver and spleen. Other abdominal viscera are involved infrequently. We present four cases of abdominal sarcoidosis demonstrating a range of CT findings.

Role of CD11a and CD11b in ischemic acute renal failure in rats

Leukocytes, particularly neutrophils, have been implicated in ischemic-reperfusion organ injury (IRI). However, their role in kidney IRI is controversial. Leukocytes express the adhesion molecules CD11/CD18 on their surface, which mediate many functions that can lead to tissue damage. To determine the role of CD11a and CD11b in IRI in the kidney, uninephrectomized Sprague-Dawley rats were pretreated with monoclonal antibodies (MAbs) directed against CD11a and CD11b or control MAbs. The serum creatinine (SCr), complete blood count, and kidney histopathological damage scores (PDS) (scale: 0-4) were assessed prior to and 24 h after 60 min of ischemia. Mean SCr 24 h after ischemia was significantly decreased in the anti-CD11a- and -CD11b-treated group compared with the control MAb-treated group (2.5 +/- 0.3 mg/dl vs. 3.4 +/- 0.2 mg/dl, P < 0.05). PDS were also reduced in the CD11a and CD11b group compared with controls (2.7 +/- 0.2 vs. 3.5 +/- 0.1, P < 0.001). These data show that the CD11/CD18 leukocyte adhesion pathway plays a role in mediating ischemic acute renal failure in rats.

Nutritional implications of recombinant human erythropoietin therapy in renal disease

The treatment of anemia in patients with renal failure has been dramatically changed with the development of recombinant human erythropoietin (r-HuEPO). This review discusses the pathogenesis of the anemia renal failure and the biology of erythropoietin. Causes of poor response to r-HuEPO therapy are outlined, and the importance of adequate available iron is highlighted. Parameters used to measure iron adequacy include serum iron levels, transferrin saturation, and ferritin levels. Other nutritional deficiencies, such as folic acid and vitamin B-12, can also impair r-HuEPO response. Clearly, the advent of r-HuEPO treatment for patients with renal failure and anemia has brought another dimension to the care of these patients. Optimal nutrition management is critical for the success of this new agent.