Experimental hypoxemic hypoxia: Changes in R2* of brain parenchyma accurately reflect the combined effects of changes in arterial and cerebral venous oxygen saturation

A two-dimensional T₂*-weighted gradient-echo sequence was used to image the rat brain before and during graded hypoxemia. Changes in R₂* (δR₂*) with respect to the control state were calculated for brain parenchyma and were compared with changes in hemoglobin saturation measured from both arterial and jugular venous blood samples. δR₂* was first correlated with the changes in arterial (δYa) and venous (δYv) hemoglobin saturations individually. Although a general trend toward a linear relationship with δR₂* was observed for both δYa and δYv, neither alone was strong (correlation coefficients r = 0.71 and 0.75 for δYa and δYv, respectively, and standard errors of the regression (SER) = 0.52 and 0.48 for δYa and δYv, respectively). However, when an “effective” cerebral blood hemoglobin saturation change (δYb) was constructed that takes into account the approximate weighting of the contributions from the arterial and venous phases of the circulation (δYb = 0.75 × δYv + 0.25 × δYa), a stronger correlation with δR₂* was obtained and there was less variance (r = 0.87 and SER = 0.35). It is concluded that an appropriate weighting of the contributions of arterial and venous phases of the circulation must be taken into account in modeling the volume susceptibility effects of deoxyhemoglobin on R₂* of brain parenchyma. In this way, a more accurate relationship between δR₂* and δYb can be obtained.     

Lymphocytes activated by the Epstein-Barr virus to produce immunoglobulin do not express CD23 or become immortalized

Epstein-Barr virus causes polyclonal activation and immortalization of a small percentage of peripheral blood B lymphocytes after in vitro infection. However, the susceptible B lymphocytes have not been identified. We have used the B lymphocyte activation antigen, CD23, as a marker for separating immortalized and non-immortalized Epstein-Barr virus-infected B lymphocytes and have identified the polyclonally-activated cells, using double staining for cytoplasmic immunoglobulin and viral antigens. The vast majority of cells expressing cytoplasmic immunoglobulin are negative for CD23 and for Epstein-Barr virus nuclear antigen, and are non-immortalized. Conversely, the CD23-positive, immortalized population are positive for Epstein-Barr virus nuclear antigen and negative for cytoplasmic immunoglobulin. These results define a diversity in the response of B lymphocytes to Epstein-Barr virus infection and suggest separate pathways for terminal differentiation and immortalization. This diversity may be important in determining the outcome of Epstein-Barr virus infection in humans.     

Intestinal obstruction due to rectal endometriosis: a surgical enigma

Obstructed rectal endometriosis is an uncommon presentation. The clinical and intraoperative presentation may present as malignant obstruction. The difficulty in making the diagnosis may delay the definitive management of the patient. We report a unique case of rectal endometriosis mimicking malignant rectal mass causing intestinal obstruction and discuss the management of the case.     

A rare complication of forgotten ureteral stent

A 35 years old lady presented with history of something coming out of the genitalia for the last 5 days. She also had history of pain in the left lumbar region which was initially investigated but the patient did not follow-up. About 15 years ago she also underwent left ureteric reimplantation. On examination, a stick like tube was protruding out of the urethral meatus which was fixed to the underlying vesical calculus. The calculus was evident radiologically and on ultrasound. The projecting portion of the stick like tube was cut and the vesical calculus with the inner portion of the tube was removed by open procedure. On evaluation of the specimen, it was found that the vesical calculus was fixed to the plastic tube which had concretions around it. This plastic tube had been placed after the ureteric reimplantation done 15 years ago and the patient was not aware of it.     

Synthesis and cloxacillin antimicrobial enhancement of 2-methylsulfonylimidazolyl-1,4-dihydropyridine derivatives

BACKGROUND AND THE PURPOSE OF THE STUDY: Hospital-acquired methicillin-resistant Staphylococcus aureus (MRSA) has been a major problem worldwide in chemotherapy of infection disease. This study was designed to assess the enhancing effects of a new group of dihydropyridine-3,5dicarboxamides, in combination with cloxacillin with distinctly different mechanisms of action against MRSAs. MATERIAL AND METHODS: Dihydropyridine-3,5-dicarboxamides with 2-methylsulfonylimidazole at 4 position 6a-k were synthesized by the reaction of corresponding aldehyde 5 with different N-aryl acetoacetamides 3 in the presence of ammonium hydroxide. Agar disc diffusion method was used to determine the antibacterial and potentiating activity of different synthetic compounds in the presence and absence of cloxacillin to evaluate their activity as modulators of multidrugresistant (MDR). RESULTS AND MAJOR CONCLUSION: The antibacterial effect of cloxacillin was enhanced by compounds 6g and 6h against cloxacillin-resistant strains (MRSA(1) and MRSA(2)). The potentiation was found 1 2 to be statistically significant (p<0.01). Compound 6g at concentration of 1000 μg/disc, caused a 329 percent potentiation of the activity of cloxacillin against MRSA(1).     

Origin of dengue type 3 viruses associated with the dengue outbreak in Dhaka, Bangladesh, in 2000 and 2001

Dengue and dengue hemorrhagic fever re-emerged in Bangladesh in 2000 and 2001 and nearly all viruses isolated were dengue type 3. Phylogenetic analyses of the envelope genes of examples of these viruses indicated that they were most closely related to recently emerged dengue type 3 viruses from neighboring Thailand and Myanmar but distinct from those from India and Sri Lanka. Since this strain of dengue virus type 3 had not been associated with unusual patterns of disease in Thailand or Myanmar, it suggested that the outbreak in Bangladesh was due to local factors after the introduction of viruses from countries to the east rather than to the evolution of an unusually virulent strain of virus in Bangladesh.