Quantification of Basal and Stimulated ROS Levels as Predictors of Islet Potency and Function

We have developed a luminol-based assay using intact islets, which allows for quantification of reactive oxygen species (ROS). In addition, an index capable of characterizing metabolic and mitochondrial integrity prior to transplantation was created based on the capacity of islets to respond to high glucose and rotenone (mitochondrial respiratory chain complex I inhibitor) by production of ROS. To validate this assay, lipid peroxidation and antioxidative defense capacity were evaluated by detection of malondialdehyde (MDA) levels and glutathione peroxidase activity (GPx), respectively. Also, flow cytometric analyses of ROS (dihydroethidine), apoptosis (Annexin V, active caspases), necrosis (Topro3), and mitochondrial membrane potential (JC-1) were done in parallel to correlate with changes in luminol-measured ROS. ATP/ADP ratios were quantified by HPLC and the predictive value of ROS measurement on islet functional potency was correlated with capacity to reverse diabetes in a streptozotocin-induced diabetic NOD.scid mouse model as well as in human transplant recipients. Our data demonstrate that levels of ROS in islets correlate with the percentage of apoptotic cells and their functional potency in vivo. The ROS indices following glucose and rotenone exposure are indicative of metabolic potency and mitochondrial integrity and can be used as surrogate markers to evaluate the quality of islets prior to transplantation.     

Modified Kalish osteotomy: A simple approach to minimizing proximal dorsal stress risers

Proximal dorsal stress risers are a potential complication to the Kalish osteotomy. The authors describe a modification to this osteotomy that is simple and effective. Since performing the wing-clip modification, there have been no observed stress risers.     

Interalar width as a guide in denture tooth selection

This study was undertaken to determine the relationship of the IAW, measured between at the widest dimension of the alae of the nose, and two other measurements of maxillary anterior teeth. The other measurements, both of which are significant in the selection and arrangement of artificial teeth used in complete dentures, were the ICTW and the ARCD measured from the distal surface of the maxillary canine on one side of the arch to the distal surface of the canine on the opposite side of the arch. No distinction was made between either the sex or the age of the subjects. The mean ICTW of 35.35 mm was 3% greater than the mean IAW of 34.28 mm. The mean ARCD of 44.85 mm was 31% greater than the mean IAW of 34.28 mm. This mean ARCD compares favorably (less than 1 mm difference) with a constructed ARCD of 45.8 mm from a tooth dimension study by Shillingburg et al. The ARCD was 44.85 mm. This measurement had not been made in the previous study examining the relationship of interalar distance to ICTW. When the IAW was plotted against the intercanine cusp tip width, a fairly strong correlation coefficient of 0.413 was exhibited. A weaker but definite correlation coefficient of 0.217 was observed when the interalar width plotted against the circumferential arc distance from distal surface to distal surface of the maxillary canines.     

Diagnostic and surgical implications of child abuse

One hundred fifty-six children younger than 13 years of age with blunt abdominal injuries were reviewed, and those injured in accidents (89%) were compared with those injured by child abuse (11%). Abused children were younger (mean age, 2 1/2 years) and all presented late to medical attention with a history that was inconsistent with their physical findings. Only 65% of abused children had physical or roentgenographic signs of prior abuse, while 35% had no signs of prior abuse. The abdominal organs injured were different; 61% of accidentally injured children suffered injuries to a single, solid organ, and only 8% had hollow viscus injuries, while 65% of abused children had hollow viscus injuries. Physicians should suspect child abuse when children have unexplained injuries (especially young children with hollow viscus injuries) even when other signs of child abuse are absent, and they should suspect hollow viscus injury in abused children.     

Altered vascular reactivity in sickle hemoglobinopathy. A possible protective factor from hypertension

Patients with sickle cell anemia have considerably less hypertension than the black population in general. Factor(s) offering "protection" from hypertension in these patients remain unknown. Hormonal and hemodynamic parameters involved in blood pressure regulation were evaluated in normotensive, stable sickle cell patients and black nonsickle normotensive controls. There was no difference in systolic, diastolic, or mean arterial blood pressure between the two groups. The characteristic hemodynamic findings of increased cardiac index, renal plasma flow, and plasma volume were observed in the sickle cell patients. Urinary sodium excretion was comparable on an ad libitum, high sodium, and low sodium diet. In contrast, plasma renin activity was greater in sickle cell patients at all levels of sodium intake in both supine and upright positions. These findings suggested possible altered vascular responsiveness to endogenous angiotensin II. Plethysmography revealed that sickle cell patients had greater forearm blood flow than normal controls and black nonsickle chronic anemic controls at rest, during cold stimulation, and during exercise. Forearm vascular resistance was significantly lower in the patients and did not increase with cold-induced, sympathetic-mediated stimulation. To assess these findings more directly, the pressor response to the exogenous administration of graded doses of angiotensin II and norepinephrine was measured. There was a marked decrease in the pressor response to angiotensin II but not to norepinephrine in the sickle cell patients. The findings in these studies indicate fundamental differences in blood pressure control in the sickle cell patient, probably at the vascular level.     

CTLA-4 is required for the induction of high dose oral tolerance

Mucosal and systemic administrations of high dose antigens induce long- lasting peripheral T cell tolerance. We and others have shown that high dose peripheral T cell tolerance is mediated by anergy or deletion and is preceded by T cell activation. Co-stimulatory molecules B7-1 (CD80)/B7-2 (CD86) and their counter-receptors CD28/CTLA-4 play pivotal roles in T cell activation and immune regulation. In the present study, we examined the roles of the B7 co-stimulation pathway in the generation of high dose peripheral T cell tolerance. We found that blocking B7:CD28/CTLA-4 interaction at the time of tolerance induction partially prevented T cell tolerance, whereas selective blockade of B7:CTLA-4 interaction completely abrogated peripheral T cell tolerance induced by either oral or i.p. antigens. These results suggest that CTLA-4-mediated feedback regulation plays a crucial role in the induction of high dose peripheral T cell tolerance.