Acromioclavicular joint cyst and rotator cuff tear

The role of a depressor factor, atrial natriuretic peptide, in the development of arterial hypertension in adolescents with pubertal hypothalamic syndrome was studied in 52 patients and 13 healthy males aged 13-24 years. The duration of disease was 2-11 years. Radioimmunological methods were used to measure plasma atrial natriuretic peptide, plasma renin activity, and serum aldosterone. Patients with borderline arterial hypertension were found to have a significant reduction in their atrial natriuretic peptide levels, and this correlated directly with the renin-aldosterone system, demonstrating insufficiency of the depressor system in patients with pubertal hypothalamic syndrome and the involvement of atrial natriuretic peptide in the development of arterial hypertension, along with disturbances in the functional relationship between atrial natriuretic peptide and the renin-aldosterone system.     

Molecular basis of resistance to HIV-1 protease inhibition: a plausible hypothesis

The binding thermodynamics of the HIV-1 protease inhibitor acetyl pepstatin and the substrate Val-Ser-Gln-Asn-Tyr-Pro-Ile-Val-Gln, corresponding to one of the cleavage sites in the gag, gag-pol polyproteins, have been measured by direct microcalorimetric analysis. The results indicate that the binding of the peptide substrate or peptide inhibitor is entropically driven; i.e., it is characterized by an unfavorable enthalpy and a favorable entropy change, in agreement with a structure-based thermodynamic analysis based upon an empirical parameterization of the energetics. Dissection of the binding enthalpy indicates that the intrinsic interactions are favorable and that the unfavorable enthalpy originates from the energy cost of rearranging the flap region in the protease molecule. In addition, the binding is coupled to a negative heat capacity change. The dominant binding force is the increase in solvent entropy that accompanies the burial of a significant hydrophobic surface. Comparison of the binding energetics obtained for the substrate with that obtained for synthetic nonpeptide inhibitors indicates that the major difference is in the magnitude of the conformational entropy change. In solution, the peptide substrate has a higher flexibility than the synthetic inhibitors and therefore suffers a higher conformational entropy loss upon binding. This higher entropy loss accounts for the lower binding affinity of the substrate. On the other hand, due to its higher flexibility, the peptide substrate is more amenable to adapt to backbone rearrangements or subtle conformational changes induced by mutations in the protease. The synthetic inhibitors are less flexible, and their capacity to adapt is more restricted. The expected result is a more pronounced effect of mutations on the binding affinity of the synthetic inhibitors. On the basis of the thermodynamic differences in the mode of binding of substrate and synthetic inhibitors, it appears that a key factor to understanding resistance is given by the relative balance of the different forces that contribute to the binding free energy and, in particular, the balance between conformational and solvation entropy.     

Evaluation of the completion of influenza vaccination

OBJECTIVE: To find the reasons which determine failures to comply with anti-flu vaccinations, so that these can be corrected and the coverage of this preventive action be increased. DESIGN: Observational crossover study, done by means of a telephone survey of people over 65. A questionnaire with closed questions, composed after a pilot study and validated by Cronbach's alpha. SETTING: Primary Care Centre (PCC). PATIENTS: We calculated a population sample for qualitative variables (_ = 0.05; p = 0.60; e = 0.05) of 294 people over 65, chosen from the PCC records, by means of random sampling (K = 4) stratified for age and discounting the telephone selection bias. MEASUREMENTS AND RESULTS: The proportion of vaccinated patients (60.9%) obtained in our study did not significantly differ from that in the general population. The percentage of patients included in the programme for the first time was 14%. Level of satisfaction among those vaccinated was 89.4%, with 8.9% of problems detected being light. Main causes of non-vaccination were: thinking that they didn't need it (63.5%), ignorance of the campaign (35.7%), fear of the reaction (24.3%), forgetting (10.4%). The main form of access to the campaign information was from the PCC, both through individuals and posters. Lack of information was statistically significant (p < 0.00001) as a determinant of non-vaccination, without other factors (age, sex, associated pathologies...) explaining these differences. CONCLUSIONS: Individualised and on-going health education by the PCC is fundamental. This would enable the identification of the group not vaccinated due to their express refusal and the recovery of non-vaccinated patients.     

Anti-CD38 prevents the development of the adaptive response induced by X-rays in human lymphocytes

Irradiation of human lymphocytes (1 cGy X-rays, 37 degrees C) evoked an approximately 30% decrease in the frequency of micronuclei upon subsequent X-irradiation (1.5 Gy). The response was reflected in a lower micronucleus frequency but not in the DNA repair rate measured by the comet assay directly after the challenge dose. Treatment of lymphocytes with anti-CD38 antibody 1 h before irradiation with the adaptive dose prevented the development of the adaptive response measured as micronuclei frequency, but adaptation was not reflected in a lower rate of DNA repair, measured by the alkaline version of the 'comet' assay. In lymphocytes that were anti-CD38-treated and irradiated and or irradiated with the adaptive dose the rate of DNA repair was not changed. However, the mean DNA damage level in adapted anti-CD38-treated lymphocytes was significantly lower than that in the control lymphocytes at all time points. We conclude that ligation of CD38 by antibody initiates signalling that prevents the development of the adaptive response induced by X-rays. Lower chromosome damage revealed by the cytokinesis block-micronucleus test in the adapted lymphocytes is unrelated to DNA repair rate.     

Postmarketing surveillance: perspectives of a journal editor

In the absence of a systematic monitoring program for drugs newly approved by the Food and Drug Administration (FDA), reports in clinical journals provide a legitimate forum for disseminating information about unexpected pharmacologic events. A journal editor bears the responsibility for publishing educated clinical observations that meet standards of scientific rigor while not giving premature credibility to chance and dubious reports of side effects of new drugs. Often this responsibility involves overcoming the fear of bad publicity and withstanding pressures from pharmaceutical companies to print only positive information about new products. Published preliminary observations may contribute to the problem of product liability, but they also generate testable hypotheses and healthy debate. If hypotheses later prove to be incorrect, they can be refuted by systematic studies and clarified in reviews and editorials. Our goal of effective education will be reached not by self-censorship but by scientific openness.     

A 37-year-old man with multiple somatic complaints

Catecholamines and volume repletion are currently used for the treatment of septic shock. However, the prognosis of patients suffering from this condition is very poor. An overproduction of nitric oxide (NO) seems to be related to the hypotension and tissue damage of endotoxin shock. Thus, treatment with NO synthase inhibitors has been proposed. Using a rat model of septic shock we have studied the effects of noradrenaline or the NO synthase inhibitor, NG-nitro-L-arginine methylester (L-NMMA) on arterial pressure, tissue damage and NO production. Anaesthetized rats treated with Salmonella typhosa showed a decrease in blood pressure accompanied by an increase in the plasma concentration of cytosolic enzymes (transaminases and lactate dehydrogenase, markers of cell disruption) and nitrite plus nitrate (NO2-/NO3-, markers of NO production). A large proportion of these animals (40%) died before the end of the experiment. Co-treatment with noradrenaline resulted in temporary maintenance of arterial pressure followed by a decline, despite the dose being increased progressively. No differences were observed in plasma cytosolic enzymes, NO2-/NO3- or mortality compared with animals treated with lipopolysaccharide (LPS) alone. In contrast, administration of L-NMMA (10 mg kg-1) to septic animals prevented the fall in blood pressure and death caused by endotoxin. This treatment markedly diminished cell disruption, as measured by the plasma levels of necrosis enzymes, and partially, but significantly, reduced the production of NO as assessed by plasma NO2-/NO3-. We conclude that tissue damage in septic shock is related to the overproduction of NO and not exclusively to the hypotension that follows this increased production. Thus, maintenance of blood pressure with catecholamines fails to improve cellular damage. Instead, partial inhibition of NO generation is sufficient to ameliorate the haemodynamic and tissue-damaging effects of septic shock and improves survival in this model of endotoxaemia.     

Transoesophageal echocardiographic assessment of haemodynamic function during laparoscopic cholecystectomy

We have measured cardiovascular changes associated with insufflation of carbon dioxide and the reverse Trendelenburg position during laparoscopic cholecystectomy, using transoesophageal echocardiography in 13 healthy patients. End-tidal carbon dioxide values increased after insufflation of carbon dioxide, with values significantly (P < 0.05) increased after lateral tilt positioning. Creation of a pneumoperitoneum was associated with increases (P < 0.05) in left ventricular end-systolic wall stress, concomitant with increases (P < 0.01) in peak airway pressure and systemic arterial pressure. In addition, left ventricular end-diastolic area decreased (P < 0.05) after reverse Trendelenburg positioning. Left ventricular ejection fraction was maintained throughout the study.     

A major isoform of the maize plasma membrane H(+)-ATPase: characterization and induction by auxin in coleoptiles

The plasma membrane (PM) H(+)-ATPase has been proposed to play important transport and regulatory roles in plant physiology, including its participation in auxin-induced acidification in coleoptile segments. This enzyme is encoded by a family of genes differing in tissue distribution, regulation, and expression level. A major expressed isoform of the maize PM H(+)-ATPase (MHA2) has been characterized. RNA gel blot analysis indicated that MHA2 is expressed in all maize organs, with highest levels being in the roots. In situ hybridization of sections from maize seedlings indicated enriched expression of MHA2 in stomatal guard cells, phloem cells, and root epidermal cells. MHA2 mRNA was induced threefold when nonvascular parts of the coleoptile segments were treated with auxin. This induction correlates with auxin-triggered proton extrusion by the same part of the segments. The PM H(+)-ATPase in the vascular bundies does not contribute significantly to auxin-induced acidification, is not regulated by auxin, and masks the auxin effect in extracts of whole coleoptile segments. We conclude that auxin-induced acidification in coleoptile segments most often occurs in the nonvascular tissue and is mediated, at least in part, by increased levels of MHA2.     

The catalytic core of RNase P

A deletion mutant of the catalytic RNA component of Escherichia coli RNase P missing residues 87-241 retains the ability to interact with the protein component to form a functional catalyst. The deletion of this phylogenetically conserved region significantly increases the Km, indicating that the deleted structures may be important for binding to the precursor tRNA substrate but not for the cleavage reaction. Under some reaction conditions, this RNase P deletion mutant can become a relatively non-specific nuclease, indicating that this RNA's catalytic center may be more exposed. The catalytic core of the RNase P is formed by less than one third of the 377 residues of the RNase P RNA.