Xeroderma pigmentosum cells with normal levels of excision repair have a defect in DNA synthesis after UV-irradiation.

Cells cultured from most patients suffering from the sunlight-sensitive hereditary disorder xeroderma pigmentosum are defective in the ability to excise ultraviolet light (UV)-induced pyrimidine dimers from their DNA. There is, however, one class of these patients whose cells are completely normal in this excision repair process. We have found that these cells have an abnormality in the manner in which DNA is synthesized after UV-irradiation. The time taken to convert initially low-molecular-weight DNA synthesized in UV-irradiated cells into high-molecular-weight DNA similar in size to that in untreated cells is much greater in these variants than in normal cells. Furthermore, this slow conversion of low to high-molecular-weight newly synthesized DNA is drastically inhibited by caffeine, which has no effect in normal cells. Two cell lines from classes of xeroderma pigmentosum that are defective in excision-repair show intermediate effects, with regard to both the time taken to convert newly synthesized DNA to high molecular weight and the inhibition of this process by caffeine.     

Orofacial neuralgia associated with a middle cerebral artery aneurysm

Chronic orofacial pain of neuropathic origin can present diagnostic and management dilemmas to dental practitioners and also affects the patient's quality of life. Intracranial aneurysms are a potential cause of stroke (e.g. sub‐arachnoid haemorrhage) that is usually associated with, high rates of mortality and morbidity. A patient who had been previously managed for symptoms of temporomandibular joint disorder (TMD) presented with sharp, shooting pain of moderate intensity. It was precipitated by swallowing, and radiated to the right throat, posterior border of the mandible, ear and temporomandibular joint. Clinical and radiological investigations ruled out odontogenic pain, TMD and other more common types of facial pain. Magnetic resonance imaging revealed a 7 × 6 mm aneurysm in the right middle cerebral artery (MCA) which was subsequently surgically clipped. Interestingly, the facial pain resolved after this procedure. Compression of the insular region of the brain innervated by the trigeminal, glossopharyngeal and vagus nerves provides a plausible explanation for the pain reported. To our knowledge, this is the first case of facial neuralgia associated with an aneurysm in the MCA which emphasizes the importance of a multidisciplinary approach in the diagnosis and management of unusual cases of chronic orofacial pain.     

Recombinant vaccinia viruses expressing GP46/M-2 protect against Leishmania infection.

Leishmania is a genus of parasitic protozoa capable of causing a spectrum of human diseases. The GP46/M-2 membrane glycoprotein has been demonstrated in a murine model system to elicit a protective immune response against infection with Leishmania amazonensis; in highly susceptible BALB/c mice, immunization leads to significant protection against infection. In the present study, for induction of long-term immunological effects, two recombinant vaccinia viruses, derived from the wild type and attenuated variant 48-7 and expressing the GP46/M-2 protein, were constructed; to ensure safety, we used the attenuated vaccinia virus mutant (48-7) as a live vector. Susceptible BALB/c mice immunized with either GP46/M-2-recombinant vaccinia virus were significantly protected against infection with L. amazonensis; 45 to 76% of the animals were completely protected (sterile) against a challenge inoculum of 10(3) infective organisms. The protectively immunized animals demonstrated T- and B-cell-dependent immunological responses; both lymphokine responses as well as antibody responses and long-term memory are indicative of T-cell activation. This first report of the use of a recombinant vaccinia virus to induce protection against a Leishmania infection indicates that recombinant vaccinia viruses should be of value in the design of a safe and effective vaccine against this parasitic disease.     

CC and CXC chemokines in breastmilk are associated with mother-to-child HIV-1 transmission

INTRODUCTION: CC and CXC chemokines may play a role in mother-to-child HIV-1 transmission by blocking HIV-1 binding to chemokine receptors and impeding viral entry into cells. METHODS: To define correlates of breastmilk chemokines and associations with infant HIV-1 acquisition, chemokines in breastmilk and infant HIV-1 infection risk were assessed in an observational, longitudinal cohort study. We measured MIP-1alpha, MIP-1beta, RANTES, and SDF-1 in month 1 breastmilk specimens from HIV-1-infected women in Nairobi and HIV-1 viral load was calculated in maternal plasma and breastmilk at delivery and 1 month postpartum. Infant infection status was determined at birth and months 1, 3, 6, 9, and 12. RESULTS: Among 281 breastfeeding women, 60 (21%) of their infants acquired HIV-1 during follow-up, 39 (65%) of whom became infected intrapartum or after birth. MIP-1alpha, MIP-1beta, RANTES, and SDF-1 were all positively correlated with breastmilk HIV-1 RNA (P<0.0005). Women with clinical mastitis had 50% higher MIP-1alpha and MIP-1beta levels (P<0.001 and P=0.006, respectively) and women with subclinical mastitis (breastmilk Na(+)/K(+)>1) had approximately 70% higher MIP-1alpha, MIP-1beta and RANTES (P<0.002 for all) compared to women without mastitis. Independent of breastmilk HIV-1, increased MIP-1beta and SDF-1 were associated with reduced risk of infant HIV-1 (RR=0.4; 95% CI 0.2-0.9; P=0.03 and RR=0.5; 95% CI=0.3-0.9; P=0.02, respectively) and increased RANTES was associated with higher transmission risk (RR=2.3; 95% CI 1.1- 5.3; P=0.04). CONCLUSIONS: These observations suggest a complex interplay between virus levels, breastmilk chemokines, and mother-to-child HIV-1 transmission and may provide insight into developing novel strategies to reduce infection across mucosal surfaces.     

Thrombospondin mediates the cytoadherence of Plasmodium falciparum- infected red cells to vascular endothelium in shear flow conditions

Cerebral malaria is thought to involve specific attachment of Plasmodium falciparum-infected knobby red cells to venular endothelium. The nature of surface ligands on host endothelial cells that may mediate cytoadherence is poorly understood. We have investigated the effects of soluble thrombospondin, rabbit antiserum raised against thrombospondin, and human immune serum on cytoadherence of parasitized erythrocytes in ex vivo mesocecum vasculature. Preincubation of infected red cells with soluble thrombospondin or human immune serum inhibits binding of infected red cells to rat venular endothelium. Infusion of the microcirculatory preparation with rabbit antithrombospondin antibodies before perfusion of parasitized erythrocytes also resulted in decreased cytoadherence. In addition, incubation of infected cells with human immune sera obtained from malaria patients significantly inhibited the observed cytoadherence. Our results indicate that thrombospondin mediates binding of infected red cells to venular endothelium and may thus be involved in the pathogenesis of cerebral malaria.     

Expression of pannexin isoforms in the systemic murine arterial network

Aims: Pannexins (Panx) form ATP release channels and it has been proposed that they play an important role in the regulation of vascular tone. However, distribution of Panx across the arterial vasculature is not documented. Methods: We tested antibodies against Panx1, Panx2 and Panx3 on human embryonic kidney cells (which do not endogenously express Panx proteins) transfected with plasmids encoding each Panx isoform and Panx1(-/-) mice. Each of the Panx antibodies was found to be specific and was tested on isolated arteries using immunocytochemistry. Results: We demonstrated that Panx1 is the primary isoform detected in the arterial network. In large arteries, Panx1 is primarily in endothelial cells, whereas in small arteries and arterioles it localizes primarily to the smooth muscle cells. Panx1 was the predominant isoform expressed in coronary arteries, except in arteries less than 100 μm where Panx3 became detectable. Only Panx3 was expressed in the juxtaglomerular apparatus and cortical arterioles. The pulmonary artery and alveoli had expression of all 3 Panx isoforms. No Panx isoforms were detected at the myoendothelial junctions. Conclusion: We conclude that the specific localized expression of Panx channels throughout the vasculature points towards an important role for these channels in regulating the release of ATP throughout the arterial network.