Reversible Adsorption of Soluble Hexameric Insulin onto the Surface of Insulin Crystals Cocrystallized with Protamine: An Electrostatic Interaction

Mixing pharmaceutical preparations of soluble neutral regular insulin solution (NRI) and neutral protamine Hagedorn (NPH) crystalline insulin suspension leads to a reduction in the measurable amount of soluble insulin in the formulation supernatant. However in spite of the loss in soluble insulin, the time-actions of these components have been shown, in clinical trials, to be unaffected. The interaction between these different physical forms of insulin has been studied using reversed-phase HPLC, isothermal titrating calorimetry, and Doppler electrophoretic light scattering analysis. Sorbent surface and solution perturbation studies revealed that the NRI adsorbs to the surface of the NPH crystal with an equilibrium constant ranging from 10⁴ M^–1 to 10⁷ M^–!, depending on the protamine concentration, pH, ionic strength, and temperature. This adsorption behavior suggests that the binding is mediated by electrostatic interactions arising between the positively-charged NPH crystal and the negatively-charged NRI hexamer. Doppler electrophoretic light scattering results, used to probe the pH-dependent surface charge of NPH and soluble insulin hexamer, support the conclusion that electrostatic interactions mediate the adsorption process. Adsorption studies under physiological conditions indicate that the elevated temperature and ionic strength, in a subcutaneous depot, are sufficient to lead to the dissociation of the NRI/NPH complex that exists in these NPH mixture formulations.     

Lobar Pulmonary Edema Due to Mitral Regurgitation: Diagnosis by Echocardiography

A bstract One etiology of unilateral lobar pulmonary edema is mitral regurgitation. Echocardiography is able to demonstrate the retrograde flow of blood into the pulmonary veins and allows timely diagnosis and treatment planning. Correction of mitral regurgitation is followed by resolution of the radiographic abnormality.     

Age-Dependent Accumulation of Hybrid Vasopressin-Oxytocin Gene Products but not Hybrid Oxytocin-Vasopressin Products in the Endoplasmic Reticulum of Brattleboro Rats

The age-dependence of the incidence of magnocellular neurosecretory neurons containing abnormal accumulations of peptide in the rough endoplasmic reticulum was examined in homozygous Brattleboro rats and in their wild-type Long Evans counterparts. Neurons in which the immunophenotype of the peptide aggregates indicate that somatic cross-over mutations involving the 5' end of the vasopressin gene and the 3' end of the oxytocin gene have occurred, increased with age in homozygous Brattleboro rats, reaching a maximum of 24 cells per hypothalamus (approximately 0.6% of the vasopressin neurons). The increase occurred in both male and female animals but was significantly greater in females. The average incidence of such cells was 6 times greater in the supraoptic than in the paraventricular nucleus. No such cells could be detected in either nucleus of Long Evans rats despite the evidence for hybrid mRNA in these animals. Moreover, no accumulation of peptide translated from the hybrid mRNAs derived from the 5' end of the oxytocin gene and the 3' end of the vasopressin gene could be detected in either Brattleboro or Long Evans animals. These results strongly suggest that the accumulation of peptide in the rough endoplasmic reticulum of vasopressin neurons in homozygous Brattleboro rats is due to an abnormality other than the somatic crossing-over mutation. A second type of abnormal magnocellular neuron with accumulations of peptide in the rough endoplasmic reticulum, in which the immunophenotype of the peptide reveals products derived only from the oxytocin precursor, was present in both Long Evans and Brattleboro rats, but did not increase with age in Brattleboro rats. The incidence of these cells was similar in the supraoptic and paraventricular nuclei.     

Controlled Release of Substituted Benzole and Naphthoic Acids Using Carbopol ® Gels: Measurement of Drug Concentration Profiles and Correlation to Release Rate Kinetics

Purpose. The objective of this study is to correlate drug release mechanism with measured drug concentration profiles in gel layers of Carbopol^® matrices containing mesalamine or benzoic acid. Methods. Release rate experiments with Carbopol^® matrices were performed using a rotating disk apparatus. Matrices were frozen and the gel layer in the matrices was sliced using a microtome in a cryostat. Drug concentration profiles were determined by direct measurement of the concentration of the drug in the gel slices. The pH of the slices was measured using microelectrodes, and water content was measured by Karl Fisher titration. Results. The concentration gradient in mesalamine matrices decreased over time and correlated with square root of time release rate kinetics. The concentration profiles of benzoic acid were unchanged over time and correlated with zero order release rate kinetics. Carbopol gel layers were highly hydrated (93–95% water). Gel layers in matrices with mesalamine had a more alkaline microenvironmental pH. This higher pH resulted in increased growth of the thickness of the gel layer and a reduction drug diffusivity in comparison to benzoic acid matrices. Conclusions. The release rate kinetics of mesalamine and benzoic acid correlated to the measured concentration profiles. The shape of the concentration profiles is determined by the rate of growth of the Carbopol^® gel layer and drug diffusivity.     

Increasing prevalence of high degree resistance amongst Salmonella to different antibiotics.

National Salmonella & Escherichia Centre situated at Central Research Institute, Kasauli receives Salmonella strains from all over the country. Eight hundred and fourteen Salmonella strains belonging to 14 serotypes received during 1986 were studied for antibiotic resistance and Minimum Inhibitory concentration (MIC) with regard to ampicillin (A), chloramphenicol (C), furazolidone (Fz) and gentamicin (G). Resistance to ampicillin was found to be highest (80%) and furazolidone the least (0.1%). Similarly a large number of strains (31%) had very high MIC values greater than 640 mcg per ml for chloramphenicol, whereas only 3.4% strains were found to have MIC values greater than 640 mcg per ml for gentamicin. The present findings have been discussed in the light of similar data published from this Centre earlier and from other sources in India.     

Prognostic Factors in Myeloma: What They Tell Us About the Pathophysiology of the Disease

Prognostic factors in myeloma are not only important for allowing comparisons to be made between therapeutic protocols but they also provide us with an insight into the pathophysiology of the disease and important mechanisms which result in disease progression. Prognostic factors in myeloma relate to the inherent proliferative capacity of the malignant clone, tumor bulk, renal function and other factors which reflect tumor host and host tumor interactions. The highly significant effect of the labelling index (LI) suggests that the clonogenic cell is ontologically very close to the malignant plasma cell on which the labelling index is derived. The explanation for the important role of the β2-microglobulin (β2M) level over and above its reflection of renal function is as yet unclear.     

Variation in the diagnosis of vesicoureteric reflux using micturating cystourethrography

  Variability in the interpretation of micturating cystourethrography by paediatric radiologists for the diagnosis of vesicoureteric reflux in children was evaluated. All 265 micturating cystourethrograms (MCUs) that were available from 304 consecutive children aged 0.5 – 61 months  –  who were investigated after their first urine infection between 1993 and 1995 as part of a prospective cohort study  –  were selected for interpretation. Three experienced paediatric radiologists from the same department independently interpreted the MCUs according to the grading system of the International Reflux Study in Children, from grades 0 to V, with the presence of intrarenal reflux also noted. Apart from being informed that urine infection was the indication for the MCU, no other clinical information was given to the radiologists. The indices of variability used were the percentage of agreement and the kappa statistic, expressed as a percentage. Both measures were weighted with integers representing the number of categories from perfect agreement. Disagreement was analysed for children and kidneys. For the diagnosis of vesicoureteric reflux in individual patients, including grade, the percentage of agreement was 96% – 97% (kappa 90% – 91%) and the weighted percentage of agreement was 96% – 98% (weighted kappa 93% – 94%). The same high level of agreement was present for individual kidneys, with a percentage of agreement of 97% – 98% (kappa 89% – 92%) and a weighted percentage of agreement of 98% – 99% (kappa 94% – 95%). There was near perfect agreement in the interpretation of radiological micturating cystourethrography among three experienced paediatric radiologists for the diagnosis and grade of vesicoureteric reflux. Any variations in the medical care of children suspected of having vesicoureteric reflux are not explained by differences in the reporting of this diagnostic test. Received June 19, 1996; received in revised form November 1, 1996; accepted December 6, 1996     

Prostatitis versus pelvic pain syndrome: Immunologic studies

The pathogenesis of chronic pelvic pain syndrome continues to be an enigma. The observation of inflammatory cells in urine, ejaculate, prostate fluid, and prostate tissue combined with changed local expressions of cytokines, immunoglobulins, complement, and other inflammatory markers led to the hypothesis of an involvement of the immune system in this clinical entity. This review presents a survey of the immunology-related data available for chronic pelvic pain syndrome and attempts to explain them in the context of causes and consequences.