Pericytes and the pathogenesis of diabetic retinopathy

Pericytes provide vascular stability and control endothelial proliferation. Pericyte loss, microaneurysms, and acellular capillaries are characteristic for the diabetic retina. Platelet-derived growth factor (PDGF)-B is involved in pericyte recruitment, and brain capillaries of mice with a genetic ablation of PDGF-B show pericyte loss and microaneurysms. We investigated the role of capillary coverage with pericytes in early diabetic retinopathy and the contribution to proliferative retinopathy using mice with a single functional allele of PDGF-B (PDGF-B(+/-) mice). As assessed by quantitative morphometry of retinal digest preparations, pericyte numbers in nondiabetic PDGF-B(+/-) mice were reduced by 30% compared with wild-type mice, together with a small but significant increase in acellular capillaries. Pericyte numbers were reduced by 40% in diabetic wild-type mice compared with nondiabetic wild-type controls. Pericyte numbers were decreased by 50% in diabetic PDGF-B(+/-) mice compared with nondiabetic wild-type littermates, and the incidence of acellular capillaries was increased 3.5-fold when compared with nondiabetic PDGF-B(+/-) mice. To investigate the effect of pericyte loss in the context of ongoing angiogenesis, we subjected mice to hypoxia-induced proliferative retinopathy. As a result, PDGF-B(+/-) mice developed twice as many new blood vessels as their wild-type littermates. We conclude that retinal capillary coverage with pericytes is crucial for the survival of endothelial cells, particularly under stress conditions such as diabetes. At high vascular endothelial growth factor levels, such as those in the retinopathy of prematurity model, pericyte deficiency leads to reduced inhibition of endothelial proliferation in vivo.

The influence of measles vaccination on the incidence of otosclerosis in Germany

The pathologic process of otosclerosis is characterized by an inflammatory lytic phase followed by an abnormal bone remodeling at very specific sites of predilection. There is a clear genetic predisposition with about half of all cases occurring in families with more than one affected member. Females are affected more frequently than males with an approximate 2:1 ratio. N, H, and F measles proteins as well as measles virus RNA have been demonstrated in osteoblasts, chondroblasts, and macrophages of the inflammatory phase of the disease. These observations merely show an association between measles viruses and otosclerosis. In the present study, we tried to prove that there is a causal relationship: voluntary measles vaccination has been available in Germany since 1974. In the absence of official data, we reconstructed the rate of vaccination coverage between 1974 and 2004 using information from the Robert Koch Institute (RKI, Berlin) and from the literature. From the German Federal Office of Statistics, we received the data of 64,112 patients who had been hospitalized between 1993 and 2004 and in whom otosclerosis (ICD-9: 387; ICD-10: H80) had been confirmed. We calculated the effect of measles vaccination on the incidence of hospital treatments for otosclerosis in the period from 1993 to 2004 in Germany. For this purpose, we divided the female and male otosclerosis patients treated as inpatients each year in the observation period into two age groups: those up to 25 years, who had in most cases been vaccinated (designated below as "vaccinated patients") and those over 25 years who mostly could not have been vaccinated (designated below as "unvaccinated patients"). We calculated the incidence of otosclerosis requiring inpatient treatment for the two age groups in each year in the period of observation. For external validation of the study results, the same analysis was carried out in all patients who received inpatient treatment for otitis media in the same period. Between 1993 and 2004 the incidence of hospital treatments for otosclerosis decreased to a significantly greater extent in the vaccinated patients than in the unvaccinated patients. The decline is much greater in men than in women. A comparable effect cannot be demonstrated in patients with otitis media. The results indicate that measles vaccination in Germany has resulted in a significant reduction in the number of hospital treatments for otosclerosis in the vaccinated age groups. We conclude that there is a causal relationship between measles viruses and the development of otosclerosis.

Managing chronic whiplash associated pain with a combination of low-dose opioid (remifentanil) and NMDA-antagonist (ketamine)

The aim was to investigate the efficacy of a combination of low-dose remifentanil (REMI) and ketamine (KET) compared to the single drugs and placebo (P) on whiplash associated pain (WAD) in a double-blind, randomized, placebo-controlled, cross-over study. Twenty patients with chronic (>1 year) WAD were included. Four different drug combinations were tested in four sessions: placebo/placebo (P/P), placebo/remifentanil (P/REMI), ketamine/placebo (KET/P) and ketamine/remifentanil (KET/REMI). Target concentrations were 1 and 2ng/ml (stepwise) for remifentanil and 100ng/ml for ketamine. Habitual pain intensity was assessed on a visual analogue scale (VAS). Experimental pain was assessed with electrical stimulation (single and repeated) of tibialis anterior (TA) muscle, pressure pain algometry applied over infraspinatus (IS) and TA muscles and VAS scores after intramuscular hypertonic saline infusion in TA. KET/REMI significantly reduced habitual pain. KET/REMI infused at low REMI target concentration (1ng/ml) significantly elevated electrical intramuscular pain thresholds (single and repeated). Pain thresholds to electrical stimulation were similarly increased by both P/REMI and KET/REMI at 2ng/ml target concentration. Pressure pain thresholds were increased by both KET/REMI and P/REMI. VAS-scores after intramuscular saline were also similarly decreased by both REMI combinations. Seven out of 20 subjects were non-responders (<50% pain relief). No correlation was found between effects on spontaneous pain and experimental pain. KET/REMI showed an analgesic effect on habitual pain. Experimental pain was attenuated by both combinations containing the opioid, however, KET seemed to enhance the effect of REMI on electrical pain thresholds when a low REMI target concentration was used.

Recurrent rearrangements of chromosome 1q21.1 and variable pediatric phenotypes

BACKGROUND: Duplications and deletions in the human genome can cause disease or predispose persons to disease. Advances in technologies to detect these changes allow for the routine identification of submicroscopic imbalances in large numbers of patients. METHODS: We tested for the presence of microdeletions and microduplications at a specific region of chromosome 1q21.1 in two groups of patients with unexplained mental retardation, autism, or congenital anomalies and in unaffected persons. RESULTS: We identified 25 persons with a recurrent 1.35-Mb deletion within 1q21.1 from screening 5218 patients. The microdeletions had arisen de novo in eight patients, were inherited from a mildly affected parent in three patients, were inherited from an apparently unaffected parent in six patients, and were of unknown inheritance in eight patients. The deletion was absent in a series of 4737 control persons (P=1.1x10(-7)). We found considerable variability in the level of phenotypic expression of the microdeletion; phenotypes included mild-to-moderate mental retardation, microcephaly, cardiac abnormalities, and cataracts. The reciprocal duplication was enriched in nine children with mental retardation or autism spectrum disorder and other variable features (P=0.02). We identified three deletions and three duplications of the 1q21.1 region in an independent sample of 788 patients with mental retardation and congenital anomalies. CONCLUSIONS: We have identified recurrent molecular lesions that elude syndromic classification and whose disease manifestations must be considered in a broader context of development as opposed to being assigned to a specific disease. Clinical diagnosis in patients with these lesions may be most readily achieved on the basis of genotype rather than phenotype.

Emergence and spread of Chlamydia trachomatis variant, Sweden

A variant of Chlamydia trachomatis that had escaped detection by commonly used systems was discovered in Sweden in 2006. In a nationwide study, we found that it is now prevalent across Sweden, irrespective of the detection system used. Genetic analysis by multilocus sequence typing identified a predominant variant, suggesting recent emergence.

Quantitative isolation of mouse and human intestinal intraepithelial lymphocytes by elutriation centrifugation

Intestinal intraepithelial lymphocytes (IEL) are specialized subsets of T cells with distinct functional capacities. While some IEL subsets are circulating, others such as CD8alphaalpha TCRalphabeta IEL are believed to represent non-circulating resident T cell subsets [Sim, G.K., Intraepithelial lymphocytes and the immune system. Adv. Immunol., 1995. 58: 297-343.]. Current methods to obtain enriched preparations of intraepithelial lymphocytes are mostly based on Percoll density gradient or magnetic bead-based technologies [Lundqvist, C., et al., Isolation of functionally active intraepithelial lymphocytes and enterocytes from human small and large intestine. J. Immunol. Methods, 1992. 152(2): 253-263.]. However, these techniques are hampered by a generally low yield of isolated cells, and potential artifacts due to the interference of the isolation procedure with subsequent functional assays, in particular, when antibodies against cell surface markers are required. Here we describe a new method for obtaining relatively pure populations of intestinal IEL (55-75%) at a high yield (>85%) by elutriation centrifugation. This technique is equally suited for the isolation and enrichment of intraepithelial lymphocytes of both mouse and human origin. Time requirements for fractionating cell suspensions by elutriation centrifugation are comparable to Percoll-, or MACS-based isolation procedures. Hence, the substantially higher yield and the consistent robust enrichment for intraepithelial lymphocytes, together with the gentle treatment of the cells during elutriation that does not interfere with subsequent functional assays, are important aspects that are in favor of using this elegant technology to obtain unmanipulated, unbiased populations of intestinal intraepithelial lymphocytes, and, if desired, also of pure epithelial cells.