In vivo interaction of beta-lactam antibiotics with the penicillin-binding proteins of Streptococcus pneumoniae.

The interactions of several beta-lactam antibiotics with the penicillin-binding proteins (PBPs) of Streptococcus pneumoniae have been studied using whole organisms treated with such antibiotics and subsequently with [3H]benzylpenicillin. Differences in chemical structure were shown to cause major and selective changes in the affinities of the beta-lactams for the PBPs Only 4 of the 28 compounds tested induced a specific morphological effect (enlargement of the equatorial region) under the particular conditions tested. In 12 of the 18 beta-lactams studied, a close correlation was found between the minimal inhibitory concentrations and the concentrations required to half-saturate PBP2b. However, such a correlation was no longer apparent when the bacteria were treated with the antibiotics at their minimal inhibitory concentrations. These findings are discussed in the context of various approaches that have been used to identify the growth-inhibitory targets of beta-lactam antibiotics in bacteria.     

Assessment of Synvisc treatment in osteoarthritis

Background. Viscosupplementation is a relatively new method for the treatment of osteoarthritis (OA). The main goal of this project was to assess the safety and clinical utility of Hylan G-F20 (Synvisc(R)) in the treatment of pain associated with osteoarthritis of the knee. The type and frequency of additional therapies used during Synvisc(R) treatment were also assessed. It was a prospective project designed for monitoring Synvisc(R)-prescribing habits in usual medical care.
Material and method. One hundred ninety knee joints in 187 patients were studied (OA symptoms were bilateral in 3 women). Synvisc(R) was indicated for the local treatment of pain in osteoarthritis of the knee. After the diagnosis, Synvisc(R) therapy was started at the recommended dose of 2 ml per intra-articular injection once
a week (at 1-week intervals), three injections in total. The data collected, including medical history, physical examination, radiographic examination and treatment efficacy (overall assessment performed at each visit), were recorded on case report forms designed to facilitate statistical analysis. The physicians completed visual Analogue Scale (VAS) for overall assessment of OA pain at each visit. The clinical outcome was recorded after the end of therapy. The patient data were collected by physicians taking part in this project only.
Results. In 156 cases (82.1%) either a substantial improvement or subsidence of symptoms was observed. In 34 cases (17.9%) the improvement was small or there was no change in the patient's condition. There were local adverse reactions in 2 patients (1.07%). There was no need to cease the treatment, to hospitalise a patient or to start any additional treatment. In 167 patients (89.3%) there was no need to start any non-pharmacological concomitant treatment.
Conclusions. In summary, Synvisc(R) viscosupplementation should be rated among the safest and most effective methods for the treatment of OA, for it alleviates OA-related pain, thus reducing the need for NSAIDs and steroid injections. The use of Synvisc(R) in OA patients alleviates pain regardless of sex and age, the effect being the most pronounced in patients with low- and medium-grade radiographic changes.     

Suppression of the Lytic and Bactericidal Effects of Cell Wall-Inhibitory Antibiotics

The bacteriolytic effect of beta-lactam antibiotics on Bacillus subtilis and on Streptococcus pneumoniae was found to be a function of the pH; lysis was suppressed if the pH of the pneumococcal culture was below 6.0 during penicillin treatment. In the case of B. subtilis, growth at pH 6.6 prevented penicillin-induced lysis. In pneumococci, the addition of trypsin to the growth medium also protected against lysis. The pH-dependent protection phenomenon resembled in several respects the antibiotic "tolerance" of pneumococci with a defective autolytic system. (i) At the pH nonpermissive for lysis, the bacteria retained their normal sensitivity to beta-lactam and to other cell wall inhibitors; however, instead of lysis, the drug-treated bacteria simply stopped growing. Loss of viability of the cells was also greatly reduced. (ii) Protection against lysis was independent of the dose and chemical nature of the cell wall inhibitors. (iii) The protection effect was reversible; lysis and loss of viability could be triggered by a postincubation of the drug-treated bacteria at the pH permissive for lysis.     

Role of the T cell in the genesis of angiotensin II induced hypertension and vascular dysfunction

Hypertension promotes atherosclerosis and is a major source of morbidity and mortality. We show that mice lacking T and B cells (RAG-1^−/− mice) have blunted hypertension and do not develop abnormalities of vascular function during angiotensin II infusion or desoxycorticosterone acetate (DOCA)–salt. Adoptive transfer of T, but not B, cells restored these abnormalities. Angiotensin II is known to stimulate reactive oxygen species production via the nicotinamide adenosine dinucleotide phosphate (NADPH) oxidase in several cells, including some immune cells. Accordingly, adoptive transfer of T cells lacking the angiotensin type I receptor or a functional NADPH oxidase resulted in blunted angiotensin II–dependent hypertension and decreased aortic superoxide production. Angiotensin II increased T cell markers of activation and tissue homing in wild-type, but not NADPH oxidase–deficient, mice. Angiotensin II markedly increased T cells in the perivascular adipose tissue (periadventitial fat) and, to a lesser extent the adventitia. These cells expressed high levels of CC chemokine receptor 5 and were commonly double negative (CD3⁺CD4⁻CD8⁻). This infiltration was associated with an increase in intercellular adhesion molecule-1 and RANTES in the aorta. Hypertension also increased T lymphocyte production of tumor necrosis factor (TNF) α, and treatment with the TNFα antagonist etanercept prevented the hypertension and increase in vascular superoxide caused by angiotensin II. These studies identify a previously undefined role for T cells in the genesis of hypertension and support a role of inflammation in the basis of this prevalent disease. T cells might represent a novel therapeutic target for the treatment of high blood pressure.     

Flow-cytometric immunophenotyping of normal and malignant lymphocytes.

During the past two decades, flow-cytometric immunophenotyping of lymphocytes has evolved from a research technique into a routine laboratory diagnostic test. Extensive studies in healthy individuals resulted in detailed age-related reference values for different lymphocyte subpopulations in peripheral blood. This is an important tool for the diagnosis of hematological and immunological disorders. Similar, albeit less detailed, information is now available for other lymphoid organs, e.g., normal bone marrow, lymph nodes, tonsils, thymus and spleen. Flow-cytometric immunophenotyping forms the basis of modern classification of acute and chronic leukemias and is increasingly applied for initial diagnostic work-up of non-Hodgkin's lymphomas. Finally, with multiparameter flow cytometry, it is now possible to identify routinely and reliably low numbers of leukemia and lymphoma cells (minimal residual disease).     

Secrets of success of a human pathogen: molecular evolution of pandemic clones of meticillin-resistant Staphylococcus aureus

The first European isolate of meticillin-resistant Staphylococcus aureus (MRSA) was detected in 1960. Since then MRSA has become a leading cause of nosocomial infections worldwide. Using molecular typing techniques--primarily pulsed-field gel electrophoresis (PFGE)--we identified five major MRSA clones that accounted for almost 70% of the over 3000 MRSA isolates recovered in hospitals mainly in southern and eastern Europe, South America, and the USA. Most of our surveillance studies were done in these areas. Multilocus sequencing typing (MLST) of representative isolates of this collection showed that these five pandemic MRSA clones have evolved from only two distinct ancestral genetic backgrounds, one of which can be traced back to the very first European MRSA isolates and also to meticillin susceptible S aureus strains circulating in Danish hospitals during the mid to late 1950s--i.e., shortly before the introduction of meticillin into therapy. The second lineage with a completely different MLST profile included MRSA frequently recovered in the USA, Japan, and among paediatric isolates from several parts of the world. A few isolates with a third distinct MLST type corresponding to that of EMRSA-16 were also detected in the early Danish isolates. The four structural types of mec element, the heterologous DNA segment containing the meticillin resistance determinant mecA, were present in unique combinations with the MRSA clonal types. Our findings establish evolutionary associations in the most widely spread pandemic clones of MRSA. The epidemiological factors that contributed to the massive dissemination of a few MRSA clones are not well understood. We suggest, however, that the secrets of effectiveness of MRSA could be hidden in the unique genetic background of a surprisingly few lineages of S aureus particularly well able to cope with the contemporary clinical environment.     

ADHD and overweight in boys: cross-sectional study with birth weight as a controlled factor

Population studies indicate a strong relationship between birth weight (BW) and body size in later life. However, BW as a variable was never accounted for in studies on the relationship between attention-deficit/hyperactivity disorder (ADHD) and overweight. This study aims to assess the relationship between ADHD and overweight with control of birth weight and other confounding factors. Prevalence of overweight was compared in clinical sample of 219 boys with ADHD and 396 boys without ADHD, aged 6–18 years. The following factors were controlled: BW, parents income and education level, place of residence, ADHD type, selected comorbid disorders and stimulant treatment. Overweight and obesity were diagnosed according to the criteria proposed by the International Obesity Task Force. Logistic regression analysis was used to estimate the association between ADHD and the prevalence of overweight and obesity. Boys with ADHD differed significantly from the control group in distribution of low BW (8.2 vs. 3.0 %, χ ² = 8.23, p = 0.02). Low BW was associated with a lower prevalence of overweight than normal and high BW (0 vs. 12.14 %, χ ² = 4.12, p = 0.04). Overweight was observed significantly more often in boys with ADHD (17.3 vs. 8.3 %, χ ² = 11.23, p < 0.001) even after adjustment for BW and other variables (OR = 2.44, 95 % CI 1.38–4.29, p = 0.002) and after controlling for ADHD type, stimulant treatment and selected comorbid disorders. Independently to applied analysis, obesity was not associated with ADHD. Lower birth weight is over twice more often observed in boys with ADHD than in control group. Although this phenomenon may reduce the rate of overweight in the studied group, ADHD remains strongly associated with increased prevalence of overweight.