Liability for failure to diagnose HIV infection and AIDS

In the United States a patient has sued a doctor for failing to diagnose AIDS, resulting in a two-year delay before correct diagnosis and treatment. At least one similar case has been commenced in Australia and more are likely. The time has come when courts in this country are likely to find that failure to diagnose symptoms of HIV infection and AIDS will constitute negligence.

Regulation of pyelonephritis-associated pili phase-variation in Escherichia coli: binding of the PapI and the Lrp regulatory proteins is controlled by DNA methylation

Expression of pyelonephritis-associated pili (Pap) in Escherichia coli is under a phase-variation control mechanism in which individual cells alternate between pili+ (ON) and pili- (OFF) states through a process involving DNA methylation by deoxyadenosine methylase (Dam). Methylation of two GATC sites (GATC1028 and GATC1130) within the pap regulatory region is differentially inhibited in phase ON and phase OFF cells. The GATC1028 site of phase ON cells is non-methylated and the GATC1130 site is fully methylated. Conversely, in phase OFF cells the GATC1028 site is fully methylated whereas the GATC1130 site is non-methylated. Two transcriptional activators, PapI and Lrp (leucine-responsive regulatory protein), are required for this specific methylation inhibition. DNA footprint analysis using non-methylated pap DNAs indicates that Lrp binds to a region surrounding the GATC1130 site, whereas PapI does not appear to bind to pap regulatory DNA. However, addition of Lrp and PapI together results in an additional DNaseI footprint around the GATC1028 site. Moreover, Dam methylation inhibits binding of Lrp/PapI near the GATC1028 site and alters binding of Lrp at the GATC1130 site. Our results support a model in which Dam and Lrp/PapI compete for binding near the GATC1028 site, regulating the methylation state of this GATC site and, consequently, the pap transcription state.

Colocalization of cholesterol and hydroxyapatite in human atherosclerotic lesions

Cholesterol and calcium phosphate, the latter in the form of hydroxyapatite, accumulate in atherosclerotic lesions. In this report, we demonstrate that these organic and inorganic constituents of lesions can accumulate together, closely associated in crystal agglomerates. Using the fluorescent cholesterol probe, filipin, we identified unesterified cholesterol that was associated with calcium granules in tissue sections of lesions. We also have shown that small crystallites of cholesterol can associate with preformed hydroxyapatite crystals in vitro. Scanning electron microscopy coupled with energy-dispersive X-ray analysis demonstrated the physical association of many small crystallites of cholesterol with larger crystals of hydroxyapatite. These small crystallites of cholesterol associated with hydroxyapatite stained with filipin. This contrasted with the lack of filipin staining of unassociated larger cholesterol crystals or hydroxyapatite alone. How cholesterol and calcium come to be closely associated in crystal agglomerates within atherosclerotic lesions remains to be determined.

Acute skin and fat necrosis during sepsis in a patient with chronic renal failure and subcutaneous arterial calcification

Calcification of small subcutaneous arteries and arterioles is commonly found in patients with chronic renal failure (CRF), but the syndrome of acute ischemic necrosis of the skin and subcutaneous fat supplied by these vessels is relatively uncommon. The necrosis occurs during dialysis and after successful renal transplantation, and it is often fatal. Occlusion of the calcified arteries and associated microvessels by thrombi is reported infrequently, but it is relevant to the necrosis. However, the pathogenesis remains enigmatic. In the patient described here, who had CRF, bacteremia, and laboratory evidence of disseminated intravascular coagulation (DIC), the distribution of thrombi and necrosis was mainly that of the calcified arteries which, therefore, probably played a role in the localization of the thrombi. An increased susceptibility of the endothelium of calcified vessels to the procoagulant effects of sepsis may be a contributing factor.

[Integrated care of HIV-seropositive patients: liaison psychiatry revisited]

Psychiatric, psychologic and psychotherapeutic care of HIV patients is integrated inside a specific medical institution. The psychological representations that AIDS mobilizes pervade the intense medical relationship between internists, nurses and the HIV patients. This relationship becomes the central node for the differentiation of psychologists and psychiatrists function inside the team. We propose here three different functions: the bio-psycho-social integrated care of the patients; the "binding" of psychical representatives inside the HIV patient who is in a death process; the binding of the representatives disseminated inside the medical team by the patient.

Liposome interactions with hydroxyapatite crystals: a possible mechanism in the calcification of atherosclerotic plaques

Some stages in the calcification of atherosclerotic plaques may involve associations between lipids and hydroxyapatite (HA) by surface interactions. Liposomes, artificial membranous lipid vesicles, have been used in this study as model structures for biological calcification processes. Liposome (containing cholesterol and phosphatidylcholine in most cases) suspensions were prepared by sonication, after which HA seed crystals were added to the suspensions and stirred at 37 degrees C. Aliquots of the liposome suspensions were analyzed for particle size distribution and by transmission electron microscopy and electron diffraction. The results showed that HA induced aggregation of liposomes and modifications of the microscopic shapes of the liposomes in the aggregates. These data can be explained by the electron diffraction pattern where superimposition of liposome reflection and crystal reflection exists and may suggest organic-inorganic interaction. The potential of HA crystals to induce formation of liposome aggregates may be seen as a step in atherosclerotic plaques calcification.

Absence of linkage between chromosome 11p15 markers and manic-depressive illness in a Belgian pedigree

OBJECTIVE

The original finding of genetic linkage in an Old Order Amish pedigree has been contradicted by the results of several subsequent studies. Using the same genetic parameter values, diagnostic criteria, and 11p15 genetic markers as those used to study the initial Amish population, the authors performed a linkage study of a four-generation informative pedigree in Belgium.

METHOD

Recombinant DNA technology was used to analyze three markers for the chromosome 11p15 location: the genes for tyrosine hydroxylase (TH) and insulin (INS) and the c-Harvey-ras oncogene (HRAS). Diagnoses of the relatives of a proband with bipolar affective disorder were determined with the Schedule for Affective Disorders and Schizophrenia--Lifetime Version and based on the Research Diagnostic Criteria. Relatives were considered affected if they had bipolar disorder, unipolar disorder, or cyclothymia; a diagnostic hierarchy was developed to include unipolar disorder and cyclothymia in the linkage analysis.

RESULTS

Pairwise analyses of the disease locus and each of the three polymorphisms excluded the possibility of close linkage between manic-depressive illness and the three chromosome 11p15 markers. Multipoint linkage analysis combining the information from all three genes also excluded linkage.

CONCLUSIONS

The conflict between the original results from the Amish study and the many negative reports on chromosome 11 linkage of manic-depression has been interpreted as indicating genetic heterogeneity, but heterogeneity has not been documented for the 11p15 locus. Conversely, the linkage approach has major drawbacks, so other genetic strategies should also be considered.

Risk of death among Honolulu fire fighters

To examine possible health risks associated with fire fighting, a 20-year Proportionate Mortality Ratio (PMR) study was conducted involving all male fire fighters with at least one year of service in the City of Honolulu Fire Department. The observed cause of death, as determined by the death certificates, was compared statistically to the expected numbers of deaths for all males over age 20 in Hawaii's general population. Significant increases in risk of death were found for brain cancer (Risk Ratio = 3.78), prostate cancer (Risk Ratio = 2.61), and cirrhosis of the liver (Risk Ratio = 2.3). A significant decrease in mortality was found for lung disease with a risk ratio of 0.37. No deaths were attributed to suicide nor to a category which included allergic, endocrine and nutritional diseases. Since fire fighters are known to suffer exposure to carcinogens and toxins, additional studies would be helpful in order to clarify possible risks to health associated with fire fighting on a long-term exposure basis.

[Genetics and schizophrenia]

Studies of twins, adoption and familial incidence have demonstrated that heredity plays a role in the genesis of schizophrenia. Owing to recent advances in molecular biology and computerized statistical models, analyses of pedigrees and genetic linkage have made it possible to progress in the identification and mode of transmission of genetic factors in schizophrenia. The methodology and conflicting results of these studies are reviewed, together with modern hypotheses on the mode of transmission of schizophrenia. The contribution of genetic studies to the concept of schizophrenia clinical spectrum and the new strategies of research in genetics are presented.

Crescentic IgA nephropathy as a manifestation of human immune deficiency virus infection

A 37-year-old Caucasian male homosexual presented with hematuria and rapidly progressive acute renal failure. He was found to have proteinuria and microscopic hematuria as well as RBC casts. Investigations revealed polyclonal gammopathy with five times normal serum IgA levels as well as elevated serum IgG. Renal biopsy showed evidence of crescentic IgA nephropathy with ultrastructural changes of tubuloreticular inclusions described in HIV nephropathy. He was found to be positive for human immunodeficiency viral antibodies. Renal function improved during follow-up after two doses of 1 g each of methylprednisone. In our opinion, this is the first case of HIV-related crescentic IgA nephropathy. HIV testing should be performed more frequently in patients presenting with acute glomerular diseases.

Alpha-2-adrenoreceptor binding as a possible vulnerability marker for affective disorders

The affinity (1/Kd) and density (Bmax) of alpha 2-adrenoreceptors in platelet membranes were studied in patients with major depressed illness (n = 10), affected first-degree relatives (n = 17), nonaffected first-degree relatives (n = 44) and controls (n = 31). The alpha 2 selective antagonist 3H-yohimbine was used as the radioligand. The mean Bmax values of affected subjects (probands and relatives) were significantly lower than those of controls. There was no difference in Kd values between the controls and affected subjects. There was a positive gradient of the mean Bmax values from the groups of probands to affected relatives, unaffected relatives and control subjects. A familial effect of Bmax values between members of the same families confirms a genetic control of alpha-receptor affinity. These results support the hypothesis that the density of alpha 2-adrenoreceptors, evaluated by 3H-yohimbine binding on human platelets, could be a potential vulnerability marker for affective disorder.

DSC, X-ray and NMR properties of cholesterol-cholestanol-dihydrate crystals

The melting point, X-ray diffraction and longitudinal relaxation time (T1) of cholesterol-cholestanol-dihydrate crystals (CC2W) were studied in an effort to produce new experimental data related to atherosclerotic plaques. The crystals were precipitated from ethanolic solutions at several cholesterol: cholestanol (CS:CN) ratios. The melting point of CC2W crystals obtained at the CS:CN ratio 75:25, 50:50, 25:75 was 122-124 degrees C. The X-ray patterns recorded from these crystals of the same CN:CS ratios showed two additional diffraction peaks, as compared to those of CN and CS patterns. On the other hand, the values of T1 relaxation time measured by proton magnetic resonance were different for every CS:CN ratio for the various solution compositions. This latter method seems to be more precise for the detection of the presence of coprecipitated components in the CC2W mixed crystals than X-ray or thermal analysis. The results suggest that CN and CS do not have to be present in equimolar quantities in order for CC2W crystals to be formed. The presence of CC2W in the blood may have significance in the nucleation of cholesterol crystals in atherosclerotic plaques.

Dependence of the substrate specificity and kinetic mechanism of horse-liver alcohol dehydrogenase on the size of the C-3 pyridinium substituent. 3-Benzoylpyridine-adenine dinucleotide

The kinetic mechanism and the substrate specificity of liver alcohol dehydrogenase are changed when 3-benzoylpyridine-adenine dinucleotide is used as coenzyme. Only primary alcohols are substrates of the enzyme and with ethanol the mechanism becomes rapid-equilibrium random bi-bi. According to model building experiments on a graphic display, the benzoyl group partially enters the substrate binding site, whereas the essential interactions between coenzyme and enzyme are preserved. This restraint on the substrate binding site provides a molecular explanation for the observed dependence between coenzyme and substrate chemical structures.

Intercellular junctions of hyperplastic retinal pigment epithelium

In rats with retinopathies induced by excess fluorescent light or injections of urethane, the retinal pigment epithelium (RPE) undergoes focal hyperplasia. Neither intravascularly injected horseradish peroxidase or lanthanum nitrate penetrated the sensory retina at these hyperplastic sites. Electron microscopy revealed that this was due to the persistence of intact tight junctions among a single layer of hyperplastic cells facing the sensory retina. These junctions prevented intraocularly injected microperoxidase from passing as well. Cells within the hyperplastic foci were connected only by adherent junctions that presented no permeability barrier.

Adaptation to Potassium

Precise control of the potassium concentration in extracellular fluids is critical to normal vertebrate physiology. During acute alterations in potassium intake, both secretory epithelial and other cells (such as muscle cells) help maintain potassium balance. During chronic potassium loads the capacity for potassium secretion by the epithelia that line the nephron and colon is increased, and during chronic dietary potassium restriction the capacity for reabsorption is increased.

Evidence that aldosterone influences transport in target tissues by dissimilar mechanisms

The present study was performed to answer the question: Is the action of aldosterone on electrolyte transport and electrical properties similar in all target tissues? Studies were performed in vivo in control animals and rats with secondary hyperaldosteronism, caused by a sodium-free diet, to compare the effects of hyperaldosteronism on distal colon with hormone-induced changes in proximal colon. In distal colon aldosterone increased net sodium absorption and potassium secretion approximately threefold. Transmural potential difference increased from -15 +/- 2 to -83 +/- 3 mV (lumen negative) and ISC rose from 167 +/- 26 to 1,023 +/- 17 microA X cm-2. These aldosterone-induced responses were completely inhibited by 0.1 mM amiloride. In contrast, in proximal colon potential difference was unchanged or increased slightly in experimental animals and ISC increased only 28% above control, although increases in net sodium and potassium transport were similar to changes observed in distal colon. Amiloride did not reduce sodium absorption in proximal colon of animals with hyperaldosteronism; ISC was decreased by 43%. These studies demonstrate that rat proximal colon is an aldosterone-sensitive tissue, but that the mechanism by which aldosterone influences sodium transport is not identical in distal and proximal portions of colon.

Role of aldosterone in the mechanism of potassium adaptation in the initial collecting tubule

Studies were performed on the initial collecting tubule of the rat to determine whether potassium adaptation in this nephron segment is aldosterone-dependent. Previous studies demonstrated that chronic potassium loading, in animals with intact adrenal glands, caused an increase in transepithelial potential difference in late distal convolution, an increase in surface density of the basolateral cell membrane, SVBLM, of principal cells in the initial collecting duct, and a rise in plasma aldosterone levels. The present study shows that epithelial changes that characterize dietary potassium loading are not dependent on hyperaldosteronism, since potential difference (-47 +/- 1 vs. 40 +/- 3 mV, lumen negative) and SVBLM (2.91 +/- 0.11 vs. 2.53 +/- 0.09 micron2/micron3) increased significantly (P less than 0.05) in the late distal convolution of adrenalectomized, hormone-replaced animals in which plasma aldosterone levels were maintained at basal values of approximately 5 ng/dl. In addition, these experiments suggest that the initial collecting tubule is sensitive to the action of aldosterone, at physiological plasma levels, since chronic hyperaldosteronism, in the absence of potassium loading, increased SVBLM in initial collecting tubule cells. In contrast to other mineralocorticoid-sensitive tissues, however, neither the acute or chronic administration of aldosterone caused an increase in potential difference in late distal convolution. These results suggest that the mechanism by which aldosterone stimulates electrolyte movement is not identical in all target tissues.

Change in inhibitory potential in urine of hyperuricosuric calcium oxalate stone formers effected by allopurinol and orthophosphates

Allopurinol and orthophosphates were used in the treatment of 25 hyperuricosuric calcium oxalate stone formers. Their urines were tested by the Discriminating Index method, which measures the potential of a urine to retard calcium oxalate precipitation in vitro. The tests were performed before any treatment was begun and about 10 days after the commencement of drug intake. An insignificant effect by allopurinol and a markedly significant effect of orthophosphates on Discriminating Index were found. In a few of the patients, allopurinol seemed to cause a decrease in the urine's potential to retard calcium oxalate precipitation. Therefore the effect of allopurinol in 11 hyperuricosuric patients with no history of calcium oxalate stone formation was tested. In 5 of the 11 patients, the urine's potential to retard calcium oxalate precipitation decreased to levels similar to those of calcium oxalate stone formers. The results of this study suggest that hyperuricosuric calcium oxalate stone formers suffer from the same yet-undefined etiology of stone formation as other calcium oxalate stone formers. The results also question the role of uric acid in calcium oxalate stone formation and the efficacy of allopurinol in preventing this disease. It is suggested that allopurinol may even be related to stone formation in some patients.