The science of pterygia.

Pterygium is an ocular surface disease of humans attributed to chronic ultraviolet-B exposure. Clinically, the condition involves invasive centripetal growth with associated inflammation and neovascularisation. Previous clinical studies focused primarily on the clinical characteristics and surgical management of pterygia and, because of this, the pathogenesis of pterygia remains incompletely understood. However, considerable progress in this area has been achieved, providing additional insight into this complex disease. This recent evidence implicates antiapoptotic mechanisms, immunological mechanisms, cytokines, growth factors, extracellular matrix modulators, genetic factors, viral infections and other possible causative factors. Limited investigation regarding differences in pathogenesis of primary and recurrent pterygia has been performed. We summarise many of these recent discoveries concerning the pathogenesis of pterygia and describe reported differences between primary and recurrent pterygia.

Human DNA topoisomerase I inhibitory activities of synthetic polyamines: relation to DNA aggregation.

DNA aggregation by polyamines has acquired importance as a prerequisite for the cellular uptake of DNA for gene therapy. Intracellular polyamines are constitutive components of mammalian cells and their availability is critical for cell proliferation. Interference of polyamine biosynthesis by synthetic polyamines leads to cytotoxicity. Optimization of the polyamine structural parameters is necessary to control their DNA aggregation, cytotoxic or enzyme inhibitory activities. We designed two series of tetra- and hexamines and compared their human DNA topoisomerase I (top1) inhibitory effects with the DNA aggregation properties. We show that hexamines are more efficient inhibitors of DNA relaxation by top1 than tetramines and that they suppress the top1-mediated DNA cleavage while tetramines do not. The DNA aggregation abilities within two series of polyamines correlate with the length of their central methylene chain. By contrast, the top1 inhibition within two series does not show the same correlation but demonstrates a threshold inhibitory effect on going from the (CH(2))(12) to the (CH(2))(14) central chain. We show further that the structures of DNA aggregates formed by polyamines with the (CH(2))(10-12) or with the (CH(2))(14-16) chains are very different. The first are a fluid cholesteric-type phases, whereas the second are well-structured aggregates similar to columnar liquid crystals with high packing density of DNA duplexes. The structures of polyamines-induced DNA aggregates are proposed to be crucial for top1 catalysis. The structure-function correlation described here may serve as a guide for rational design of polyamines with desired DNA-aggregation or anti-top1 activities.

Community meetings on a military inpatient psychiatric unit: a question of balance.

Community meetings are a mainstay of any inpatient psychiatric unit. Although they differ in frequency, attendance, leadership, and size, they all maintain a similar purpose of acculturating the members to the values of the ward and encouraging responsible behavior and effective communication. The military inpatient psychiatric unit is no different, although it does have several unique factors that affect the management of the community meeting. Specifically, these factors are the inherent military rank structure, which often conflicts with the rank of staff and other patients, the incorporation of a civilian population into a military culture, and a greater focus on patient transitions from military to civilian society. We describe and discuss the common variables of community meetings, elucidate how the military aspects affect the meeting, and offer potential suggestions for the management of this unique large dynamic group.

The effect of intraislet somatostatin immunoneutralization on insulin secretion in the isolated perfused rat pancreas.

BACKGROUND: There is evidence of a local inhibitory effect of somatostatin on insulin secretion in the isolated human pancreas, but this has not been shown in a rat model. The possible phasic effect of somatostatin on insulin secretion has not been demonstrated. AIMS: This study was undertaken to determine if somatostatin has a local regulatory effect on phasic insulin secretion within a rat pancreas model. METHODS: The basal and glucose stimulated secretion of insulin was compared with and without immunoneutralization of somatostatin using a somatostatin antibody in an isolated perfused rat pancreas model. High concentration, high affinity monoclonal somatostatin antibody was perfused through isolated rat pancreata. Radioimmunoassay for insulin was performed on the portal effluent. RESULTS: Immunoneutralization of somatostatin during basal insulin secretion produced a rise in insulin secretion of 551 +/- 163% that approached significance. Immunoneutralization during glucose stimulated insulin secretion produced a significant rise in insulin secretion compared to the control group of 2,678 +/- 187% vs. 535 +/- 39% (p < 0.05). The phase I vs. the phase II response in the glucose stimulated pancreas was similar in the presence of control antibody, 867 +/- 351% vs. 900 +/- 398% (p = NS). With somatostatin immunoneutralization, the glucose stimulated pancreas had a significantly higher phase II response than phase I; 3,832 +/- 688% vs. 2,516 +/- 431% (p < 0.05). CONCLUSION: These data indicate that intraislet somatostatin is an inhibitor of insulin secretion in the isolated perfused rat pancreas. This effect occurs primarily in phase II of insulin secretion.

Intraislet regulation of pancreatic polypeptide secretion in the isolated perfused rat pancreas.

The present study is to determine if intraislet insulin or somatostatin regulate pancreatic polypeptide (PP) secretion in the isolated perfused rat pancreas by infusing insulin or somatostatin antisera. Isolated rat pancreata were stimulated with either 16.7 mM glucose (G) alone, G with antisomatostatin antibody (G + SA), or G with antiinsulin antibody (G + IA). G inhibited PP secretion -22 +/- 9.5 pM below basal, a decrease of 9 +/- 6.3% (n = 6; p = NS), G + IA inhibited PP secretion -10 +/- 27.2 pM below basal, a decrease of 20 +/- 15% (n = 7, p = NS), and G + SA stimulated PP secretion 18 +/- 7.1 pM above basal, an increase of 26 +/- 5% (n = 6; p < 0.05). G stimulated insulin secretion 3,144 +/- 210 pM above basal (n = 6, p < 0.05), and G + SA stimulated insulin secretion 2,695 +/- 195 pM above basal (n = 7; p < 0.05 vs. baseline, p = NS vs. G alone). G stimulated C-peptide secretion 886 +/- 175 pM above basal (n = 6; p < 0.05), G + SA stimulated C-peptide secretion 847 +/- 102 pM above basal (n = 7; p < 0.05, p = NS vs. G alone), and G + IA stimulated C-peptide secretion 834 +/- 93 pM above basal (n = 7; p < 0.05, p = NS vs. G alone). These data demonstrate that infusion of SA results in significant stimulation of PP secretion during high-G infusion, whereas IA has no effect. Infusions of SA or IA at the doses used have no effect on G-stimulated insulin or C-peptide secretion. This suggests that intraislet somatostatin may be an inhibitory regulator of PP secretion in the isolated perfused rat pancreas.

Prader-Willi syndrome--a case report of the multidisciplinary management of the orofacial problems.

A 24-year-old man with Prader-Willi syndrome presented with a class III malocclusion, featuring maxillary hypoplasia and severe enamel deficiency. Treatment involved orthodontic alignment, surgical advancement of the maxilla and restorative treatment to augment vertical facial height, improve the final occlusion and increase short clinical dental crown heights. The principal features of the syndrome and the management of this case are discussed.

Guanidinium-cholesterol cationic lipids: efficient vectors for the transfection of eukaryotic cells.

Two cationic lipids, bis-guanidinium-spermidine-cholesterol (BGSC) and bis-guanidinium-trencholesterol (BGTC)-cholesterol derivatives bearing two guanidinium groups-have been synthesized and tested as artificial vectors for gene transfer. They combine the membrane compatible features of the cholesterol subunit and the favorable structural and high pKa features of the guanidinium functions for binding DNA via its phosphate groups. Reagent BGTC is very efficient for transfection into a variety of mammalian cell lines when used as a micellar solution. In addition, both BGTC and BGSC present also a high transfection activity when formulated as liposomes with the neutral phospholipid dioleoylphosphatidyl ethanolamine. These results reveal the usefulness of cholesterol derivatives bearing guanidinium groups for gene transfer.

The efficacy of two comprehensive perinatal programs on reducing adverse perinatal outcomes.

Through the collaboration among University of California at Berkeley School of Public Health, Samuel Merritt College, and a private nonprofit, community-based medical center, the adequacy of two perinatal programs was assessed based on the pregnancy outcomes of teenaged Medi-Cal clients. Historical data from June 1991 to June 1992 were compiled on the pregnancy outcomes of 312 Medi-Cal clients, 12-18 years of age, delivering at the study medical center in Oakland, California. The effect of enrollment in two special perinatal programs, Comprehensive Perinatal Services Program (CPSP) and a school-based program, the Comprehensive Teenage Pregnancy and Parenting Program (CTAPPP), on the occurrence of adverse perinatal outcomes was examined. Adverse perinatal outcomes were defined as the occurrence of one of the following: low birthweight (< 2,500 grams), gestational age less than 37 weeks, or admission to the neonatal intensive care unit (NICU), not related to congenital syphilis. The percentage of teens experiencing adverse perinatal outcomes was 10.9% at the study hospital. No significant association was observed between CTAPPP enrollment and reduced adverse perinatal outcomes, but CPSP enrollment was associated with reduced adverse perinatal outcomes. This association persisted after controlling for potential confounders, including substandard prenatal care, which were also found to be risk factors for adverse perinatal outcomes. Enrollment in both programs simultaneously was not associated with a reduction in adverse outcomes. The significant association between CPSP enrollment and reduced adverse perinatal outcomes indicates that a more comprehensive prenatal program may be beneficial in improving birth outcomes, specifically among high-risk teenage populations.(ABSTRACT TRUNCATED AT 250 WORDS)

Potassium channels: a computer prediction of structure and selectivity.

Model structures for the pore of the potassium channels Shaker and ROMK1 are predicted. The models arise from computer simulations and suggest reasons for the striking selectivity of these channels for K+ and the blocking of ROMK1 by internal Mg2+. The modelled structure of the Shaker pore is supported by mutagenesis data. The mutagenesis experiments indicate the side chains responsible for binding to blocking agents [tetraethylammonium (TEA) and charybdotoxin (CTX)] and the model has these side chains suitably oriented for binding. An aromatic K+ binding site part way down the pore is also predicted by the Shaker pore model.

Characteristics of limbic seizures evoked by peripheral injections of lithium and pilocarpine.

The characteristics and consequences of limbic seizures evoked by single peripheral injections of lithium (3 mEq/kg) and pilocarpine (30 mg/kg) were investigated over a three-year period. The seizures occurred when 3 mEq/kg of lithium was followed 4 to 28 hours later by 30 mg/kg of pilocarpine. The seizures did not occur if the intervals were shorter or longer or if the pilocarpine preceded the lithium. The acute mortality or persistent aphagia and adipsia could be compensated by postseizure injections of acepromazine and a special milk-bread diet. Gender, age and preinjection environmental effects, but not hybrid genetics, influenced the seizure onset latency. Fifty to 100 days after the seizures massive lesions were found in the entorhinal-pyriform cortices, amygdala and selected thalamic groups.

Optical processing with residue LED/LD lookup tables.

Position-coded modulo m lookup tables (LUTs) with gate complexities equal to m(2), 2m, and 4 radicalm are discussed. The design of practical miniaturized LUTs is described along with results obtained from a prototype 7 x 7 laser diode LUT. A factored m(2) LUT technique that achieves large dynamic range is presented. Several LUT performance issues are also discussed.

Nurses' attitudes toward dimensions of nursing practice.

The purpose of this study was to examine nurses' attitudes toward nursing behaviors. The research question was: What is the relative importance that nurses attribute to certain dimensions of nursing behaviors? In order to answer this question, an attitudinal instrument was developed and administered to a sample of 196 female nurses whose names were obtained from the deans and directors of the nine NLN schools in Connecticut. Five a priori constructs were used as a basis for validation in the instrument development--the utilization of a unique body of knowledge and skills; the utilization of the nursing process; research ability; leadership ability; and teaching, prevention, and maintenance. Objectives, which were obtained from each of the nine schools in Connecticut, as well as from the NLN, constituted the items in the measuring instrument. Factor analysis of the instrument yielded seven factors, accounting for 63.1 percent of the total variance. Three of these factors were the same factors as those identified in the a priori analysis. The results of this study contribute toward a better understanding of nurses' perceptions of the importance of several identified components of the nursing role.