Interactional processes in families with depressed and non-depressed adolescents: reinforcement of depressive behavior

Problem-solving interactions were observed in 86 families of depressed adolescents and 408 families of non-depressed adolescents. Sequential analyses indicated that mothers of depressed adolescents were more likely than mothers of non-depressed adolescents to increase facilitative behavior in response to adolescent depressive behavior. Additionally, fathers of depressed adolescents were more likely than their counterparts in families of non-depressed adolescents to decrease aggressive behavior subsequent to adolescent depressive behavior. These analyses suggest that parents of depressed adolescents may be inadvertently reinforcing depressive behavior. Decreases in adolescent depressive symptomatology from year 1 to year 2 were not accompanied by changes in family interaction patterns.

Solution structure of the C-terminal SH2 domain of the p85 alpha regulatory subunit of phosphoinositide 3-kinase

Heterodimeric class IA phosphoinositide 3-kinase (PI 3-kinase) plays a crucial role in a variety of cellular signalling events downstream of a number of cell-surface receptor tyrosine kinases. Activation of the enzyme is effected in part by the binding of two Src homology-2 domains (SH2) of the 85 kDa regulatory subunit to specific phosphotyrosine-containing peptide motifs within activated cytoplasmic receptor domains. The solution structure of the uncomplexed C-terminal SH2 (C-SH2) domain of the p85 alpha subunit of PI 3-kinase has been determined by means of multinuclear, double and triple-resonance NMR experiments and restrained molecular-dynamics simulated-annealing calculations. The solution structure clearly indicates that the uncomplexed C-SH2 domain conforms to the consensus polypeptide fold exhibited by other SH2 domains, with an additional short helical element at the N terminus. In particular, the C-SH2 structure is very similar to both the p85 alpha N-terminal SH2 domain (N-SH2) and the Src SH2 domain with a root mean square difference (rmsd) for 44 C alpha atoms of 1.09 and 0.89 A, respectively. The canonical BC, EF and BG loops are less well-defined by the experimental restraints and show greater variability in the ensemble of C-SH2 conformers. The lower level of definition in these regions may reflect the presence of conformational disorder, an interpretation supported by the absence or broadening of backbone and side-chain NMR resonances for some of these residues. NMR experiments were performed, where C-SH2 was titrated with phosphotyrosine-containing peptides corresponding to p85 alpha recognition sites in the cytoplasmic domain of the platelet-derived growth-factor receptor. The ligand-induced chemical-shift perturbations indicate the amino-acid residues in C-SH2 involved in peptide recognition follow the pattern predicted from homologous complexes. A series of C-SH2 mutants was generated and tested for phosphotyrosine peptide binding by surface plasmon resonance. Mutation of the invariant Arg36 (beta B5) to Met completely abolishes phosphopeptide binding. Mutation of each of Ser38, Ser39 or Lys40 in the BC loop to Ala reduces the affinity of C-SH2 for a cognate phosphopeptide, as does mutation of His93 (BG5) to Asn. These effects are consistent with the involvement of the BC loop and BG loops regions in ligation of phosphopeptide ligands. Mutation of Cys57 (beta D5) in C-SH2 to Ile, the corresponding residue type in the p85 alpha N-SH2 domain, results in a change in peptide binding selectivity of C-SH2 towards that demonstrated by p85 alpha N-SH2. This pattern of p85 alpha phosphopeptide binding specificity is interpreted in terms of a model of the p85 alpha/PDGF-receptor interaction.

Increased density of glutamate/N-methyl-D-aspartate receptors in putamen from schizophrenic patients

Saturable radioligand binding of [3H]L-689,560 to the glycine site of the N-methyl-D-aspartate (NMDA) glutamate receptor complex was employed to determine the density of this receptor in putamen, caudate and nucleus accumbens taken post mortem from schizophrenic patients and matched controls. Receptor density was found to be significantly increased in putamen of schizophrenics (P=0.012), although no significant change was found in the other two areas studied. Further experiments following 21 days administration of haloperidol to rats provided no evidence that the increase was related to prior drug treatment.

A lasting public health response to an outbreak of HIV infection in a Scottish prison?

Between April and June 1993, 8 cases of acute clinical hepatitis B infection and 2 seroconversions to HIV infection were detected among drug injecting inmates of HM Prison Glenochil in Scotland. To prevent the further spread of infection, an initiative which involved counselling and voluntary attributable HIV testing was conducted over a 10-day period commencing at the end of June. A team of 18 counsellors and phlebotomists was brought together rapidly as part of a unique organizational exercise in the field of public health. Fourteen cases of HIV infection were identified of which 13 were almost certainly infected in Glenochil. Following the exercise, a range of harm reduction measures for injecting prisoners was introduced; these included the availability of hepatitis B vaccine, provision of bleach tablets which could be used to clean injecting equipment, a methadone detoxification programme, increased training for prison officers and improved access to drug and harm minimization counselling for inmates. By mid-1996 all these measures had been sustained and several could be found in many other prisons throughout Scotland. Follow-up investigations showed no evidence of epidemic spread of HIV during the 12 months after the initiative. While the frequency of injecting and needle/syringe sharing may have decreased over the last 3 years, these activities are still being reported and it is highly likely that transmissions of bloodborne infections, in particular hepatitis C, continue to occur. The surveillance and prevention of infections associated with injecting drug use in the prison setting remain a high public health priority.

Rn Delegation: the New Jersey Task Force recommendations

Because licensure and delegation clauses are determined state by state, all statewide home care associations need to begin a dialogue concerning delegation and how it impacts the nurse's practice and the way agencies deliver care in the community. State organizations need to communicate with each other and share concerns and experiences with other state home care organizations. Nursing boards, nursing and home health aide associations, advocates for long-term care patients, and the older population also need to be involved in the discussion. This open dialogue between many different organizations concerning delegation will ensure that patients receive safe, quality care that is also cost effective.

Long-term trial of deferiprone in 51 transfusion-dependent iron overloaded patients

Fifty-one transfusion-dependent iron-loaded adult patients (38 with thalassemia major) were treated with the orally active iron chelator deferiprone (1,2 dimethyl-3-hydroxypyrid-4-one, L1) at a dose of 75 mg/kg/d (range, 50 to 79). Twenty patients discontinued the drug and five died after a mean of 18.7 months (range, 4 to 35). Of the 20, 5 had arthropathy, 5 had gastrointestinal symptoms, 4 had a rising serum ferritin, 3 had agranulocytosis or neutropenia, 1 had tachycardia, 1 had renal failure, and 1 went abroad. Twenty-six patients continued deferiprone for a mean of 39.4 months (range, 12 to 49). Among these patients, there was no overall significant change in serum ferritin (initial mean, 2,937 microg/L; range, 980 to 5,970; final mean, 2,323 microg/L; range, 825 to 5,970) or in urine iron excretion (initial mean, 31.2 mg/24 h; range, 16.3 to 58. 2; final mean, 32.1 mg/24 h; range, 9.4 to 75.8), implying no overall change in iron stores. When the patients who had received deferiprone for longer than 3 years were considered separately, there was also no significant change in serum ferritin or urinary iron excretion. The initial serum ferritin levels in the 26 patients who continued deferiprone treatment were significantly lower than in those who discontinued the drug (P < .01). The liver iron content in 17 patients who had received deferiprone for 24 to 48 months ranged from 5.9 to 41.2 mg/g dry weight, 50% having levels above 15.0 mg, a level associated with a high risk of cardiac disease due to iron overload. In this study the drug caused fewer side effects and was more effective at maintaining iron status among patients previously well chelated and with lower initial serum ferritin levels.

Prospective study of equine colic incidence and mortality

A prospective study of one year was conducted on 31 horse farms to obtain population based estimates of incidence, morbidity and mortality rates of equine colic. Farms with greater than 20 horses were enrolled by randomly selecting horse owners from 2 adjacent counties of Virginia and Maryland. Descriptive information for 1427 horses was collected at the initiation of the study and updated at 3 month intervals. Time on the farm during the study was tabulated for each horse. When colic was reported by the owner, investigators visited the farm to obtain information about the colic. The crude incidence density rate of colic was 10.6 colic cases/100 horse-years, based on 104 cases/358,991 horse-days. The median farm specific incidence density rate was 7 cases/100 horse-years, and the range for individual farms varied from 0 to 30 colic cases/100 horse-years. A specific diagnosis was not made for 84 (81%) of colic episodes. Seventy colic episodes (67%) were treated by a veterinarian. Drugs were used in 83 (80%) colic episodes, and 78 (75%) of colic cases were mild, requiring no treatment or resolving after only one treatment. Four horses required colic surgery. Fourteen (13%) horses had more than one episode of colic during the year. Mortality from all causes of death was 2.5 deaths/100 horse-years, mortality rate for colic was 0.7 deaths/100 horse-years. Proportional mortality rate of colic, 28%, was higher than for any other cause of death. Horses less than age 2 years or greater than age 10 years had lower incidence than horses age 2-10 years. No difference in colic risk between genders was identified. Arabian horses had the lowest and Thoroughbreds the highest breed specific incidence rates. Horses used for eventing, or in training had a statistically significant higher incidence rate of colic compared to mature horses with no use (pets, retired, on pasture with no stated purpose). Horses used for lessons or with no use had the lowest incidence rates.

Prospective study of equine colic risk factors

A 1 year prospective study was conducted on 31 horse farms to identify risk factors for equine colic. Farms were randomly selected from a list from 2 adjacent counties of Virginia and Maryland, USA. The association between colic and farm or individual horse risk factors related to management, housing, pasture, use, nutrition, health and events was first examined by univariate statistical analysis. Individually significant (P < = 0.25 for farm factors, P < = 0.10 for horse factors) variables were used in a stepwise multivariable forward logistic regression to select explanatory factors (P < = 0.05). Analysis was conducted at 2 levels: farm and individual horse with farm specified as a random effects variable. No farm-level variables were significant. Significant horse-level variables included: age, odds ratio (OR) = 2.8 for horses age 2-10 years compared to < 2 years; history of previous colic, OR = 3.6 relative to no colic; changes in concentrate feeding during the year (1 per year, OR = 3.6, more than 1, OR = 2.2) relative to no changes; more than 1 change in hay feeding during the year, OR = 2.1 relative to no changes; feeding high levels of concentrate (> 2.5 kg/day dry matter, OR = 4.8, > 5 kg/day dry matter, OR = 6.3) relative to feeding no concentrate; and vaccination with monocytic ehrlichiosis vaccine during the study, OR = 2.0 relative to no vaccination. Feeding a whole grain with or without other concentrate components reduced risk, OR = 0.4, relative to feeding no whole grain. Results of the study suggest that diet and changes in diet are important risks for colic in a population of horses on farms.

Benzidine-DNA adduct levels in human peripheral white blood cells significantly correlate with levels in exfoliated urothelial cells

In a cross-sectional study of 33 workers exposed to benzidine and benzidine dyes and 15 non-exposed controls, we previously reported that exposure status and internal dose of benzidine metabolites were strongly correlated with the levels of specific benzidine-DNA adducts in exfoliated urothelial cells. We also evaluated DNA adduct levels in peripheral white blood cells (WBC) of a subset of 18 exposed workers and 7 controls selected to represent a wide range of adducts in exfoliated urothelial cells. Samples were coded and then DNA was analyzed using 32P-postlabeling, along with n-butanol extraction. One adduct, which co-chromatographed with a synthetic N-(3'-phospho-deoxyguanosin-8-yl)-N'-acetylbenzidine standard, predominated in those samples with adducts present. The median level (range) of this adduct in WBC DNA was 194.4 (3.2-975) RAL x 10(9) in exposed workers and 1.4 (0.1-6.4) in the control subjects (p = 0.0002, Wilcoxon Rank Sum Test). There was a striking correlation between WBC and exfoliated urothelial cell adduct levels (Pearson r = 0.84, p < 0.001) among exposed subjects. In addition, the sum of urinary benzidine, N-acetylbenzidine and N,N'-diacetylbenzidine correlated with the levels of this adduct in both tissues. This is the first study in humans to show a relationship for a specific carcinogen adduct in a surrogate tissue and in urothelial cells, the target for urinary bladder cancer.

Deficits of [3H]D-aspartate binding to glutamate uptake sites in striatal and accumbens tissue in patients with schizophrenia

The hypothesis involving glutamate in the neuropathology of schizophrenia has attracted great interest. Several studies report dysfunctions in glutamatergic systems, including alterations in kainate and N-methyl-D-aspartate (NMDA) receptors in various areas, as well as changes in the number of glutamate uptake sites. We have studied this further using [3H]D-aspartate binding to glutamate uptake sites as a measure of the integrity of presynaptic glutamate systems in several areas (caudate nucleus, putamen, nucleus accumbens, frontal cortex and temporal cortex) of brain tissue taken at autopsy from schizophrenic patients and controls. A significant decrease in the number of glutamate uptake sites was apparent in caudate nucleus, putamen and nucleus accumbens in the schizophrenia group, indicating an impaired glutamatergic innervation of these subcortical regions. However, no significant changes were found in the two cortical regions studied.

Systemic lupus erythematosus-associated lymphoproliferative disorder: report of a case and discussion in light of the literature

A case of autoimmune disease-associated lymphadenopathy (ADAL) with histological, immunophenotypic, Epstein-Barr virus (EBV) in situ hybridization, and genotypic analyses is presented. The patient had a well-documented history of systemic lupus erythematosus (SLE) and was found at autopsy to have massive lymphadenopathy, thymic enlargement, pulmonary nodules, and polyclonal serum dysproteinemia. Histological examination revealed a polymorphous lymphoid infiltrate containing many plasma cells, rare immunoblasts, and a pronounced arborizing vasculature. No foci of necrosis were found and there was no evidence of lymphocyte depletion. The plasma cells were immunophenotypically polyclonal and no EBV mRNA (EBER-1) or gene rearrangements were identified. The unusual gross features, which resembled a malignant lymphoproliferative process, as well as the unusual histological features make this case a notable addition to the spectrum of atypical lymphoproliferative disorders associated with an autoimmune disorder. We conclude that although reminiscent of angioimmunoblastic lymphadenopathy with dysproteinemia (AILD), this case lacks the diagnostic features of AILD, and is, perhaps, best classified as an autoimmune disease-associated lymphadenopathy (ADAL).

Family support and conflict: prospective relations to adolescent depression

The relations between family support, family conflict, and adolescent depressive symptomatology were examined longitudinally in a sample of 231 female and 189 male adolescents and their mothers. Structural equation models revealed that less supportive and more conflictual family environments were associated with greater depressive symptomatology both concurrently and prospectively over a 1-year period. Conversely, adolescent depressive symptomatology did not predict deterioration in family relationships. Depressive symptomatology and, to a greater extent, family characteristics showed high levels of stability over the 1-year period. Counter to our expectations, the relations between family variable and depressive symptomatology were similar for boys and girls. The results suggest that the quality of family interactions is relevant for understanding the development of depressive symptoms in adolescents.

Effect of practice guidelines on therapeutic bed use

Therapeutic beds, though clinically beneficial, can prove to be costly if their use is not directed. In this research utilization project, the use of therapeutic beds in five patient care units and one intensive care unit in a 300-bed acute care hospital were evaluated before and after the implementation of practice guidelines. Usage time and cost for each patient were measured and compared over the same four-month period in 1994 and 1995. Our findings indicated there were no significant differences between the two groups with regard to the time patients spent on therapeutic beds and the total cost of these beds. The mean time on the bed and the mean cost per patient were, however, lower for the practice guideline group. It was concluded that even without demonstrating significant differences, practice guidelines are a useful tool in providing a standard for nursing practice when caring for patients in the acute care setting.

Prevention of an increase in plasma cortisol during hypoglycemia preserves subsequent counterregulatory responses

The aim of this study was to determine whether preventing increases in plasma cortisol during antecedent hypoglycemia preserves autonomic nervous system counterregulatory responses during subsequent hypoglycemia. Experiments were carried out on 15 (8 male/7 female) healthy, overnight-fasted subjects and 8 (4 male/4 female) age- and weight-matched patients with primary adrenocortical failure. 5 d before a study, patients had their usual glucocorticoid therapy replaced with a continuous subcutaneous infusion of cortisol programmed to produce normal daily circadian levels. Both groups underwent identical 2-d experiments. On day 1, insulin was infused at a rate of 1.5 mU/kg per min, and 2-h clamped hypoglycemia (53+/-2 mg/dl) was obtained during the morning and afternoon. The next morning, subjects underwent an additional 2-h hypoglycemic (53+/-2 mg/ dl) hyperinsulinemic clamp. In controls, day 2 steady state epinephrine, norepinephrine, pancreatic polypeptide, glucagon, growth hormone, and muscle sympathetic nerve activity were significantly blunted (P < 0.01) compared with day 1 hypoglycemia. In marked contrast, when increases of plasma cortisol were prevented in the patient group, day 2 neuroendocrine, muscle sympathetic nerve activity, hypoglycemic symptoms, and metabolic counterregulatory responses were equivalent with day 1 results. We conclude that (a) prevention of increases of cortisol during antecedent hypoglycemia preserves many critical autonomic nervous system counterregulatory responses to subsequent hypoglycemia; (b) hypoglycemia-induced increases in plasma cortisol levels are a major mechanism responsible for causing subsequent hypoglycemic counterregulatory failure; and (c) our results suggest that other mechanisms, apart from cortisol, do not play a major role in causing hypoglycemia-associated autonomic failure.

Hydrogen exchange in chymotrypsin inhibitor 2 probed by mutagenesis

Two-dimensional NMR spectroscopy has been used to monitor hydrogen-deuterium exchange in chymotrypsin inhibitor 2. Application of two independent tests has shown that at pH 5.3 to 6.8 and 33 to 37 degrees C, exchange occurs via an EX2 limit. Comparison of the exchange rates of a number of mutants of CI2 with those of wild-type identifies the pathway of exchange, whether by local breathing, global unfolding or a mixture of the two pathways. For a large number of residues, the exchange rates were unaffected by mutations which destabilized the protein by up to 1.9 kcal mol(-1), indicating that exchange is occurring through local fluctuations of the native state. A small number of residues were found for which the mutations had the same effect on the rate constants for exchange as on the equilibrium constant for unfolding, indicating that these residues exchange by global unfolding. These are residues that have the slowest exchange rates in the wild-type protein. We see no correspondence between these residues and residues involved in the nucleation site for the folding reaction identified by protein engineering studies. Rather, the exchange behaviour of CI2 is determined by the native structure: the most protected amide protons are located in regions of hydrogen bonding, specifically the C terminus of the alpha-helix and the centre of the beta-sheet. A number of the most slowly exchanging residues are in the hydrophobic core of the protein.

Differences between chest pain observation service patients and admitted "rule-out myocardial infarction" patients

OBJECTIVE

To compare and contrast the patient characteristics of ED patients at low risk for acute cardiac ischemia who were assigned to a chest pain observation service vs those admitted to a monitored inpatient bed for "rule-out acute myocardial infarction" (R/O MI).

METHODS

This was a retrospective, cross-sectional comparison of adult patients considered at relatively low risk for cardiac ischemia and who were evaluated in 1 of 2 settings: a short-term observation service and an inpatient monitored bed. All patients had an ED final diagnosis of "chest pain," "R/O MI," or "unstable angina" during the 7-month study period. Demographic features and presenting clinical features were examined as a function of site of patient evaluation.

RESULTS

Of 531 study patients, 265 (50%) were assigned to the observation service. Younger age (OR = 1.75, 95% CI 1.26, 2.44, for each decrement of 20 years), the complaint of "chest pain" (OR = 2.35, 95% CI 1.34, 4.12), and the absence of prior known coronary artery disease (OR = 1.64, 95% CI 1.13, 2.38) were the principal independent factors associated with assignment to a chest pain observation service bed.

CONCLUSIONS

Patients evaluated in a chest pain observation service appear to have different clinical characteristics than other individuals admitted to a monitored inpatient bed for "R/O MI." Investigators should address differences in clinical characteristics when making outcome comparisons between these 2 patient groups.

The adaptability of Escherichia coli thioredoxin to non-conservative amino acid substitutions

The adaptability of Escherichia coli thioredoxin to the substitution of a series of non-natural amino acids has been investigated. Different thiosulfonated alkyl groups were inserted into the hydrophobic core of the protein in position 78 via disulfide bonding with a buried cysteine residue as previously described (Wynn R, Richards FM. 1993. Unnatural amino acid packing mutants of Escherichia coli thioredoxin produced by combined mutagenesis/chemical modification techniques. Protein Sci 2:395-403). The side chains added to the cysteine included methyl, ethyl, n-propyl, n-butyl, n-pentyl, and cyclo-pentyl derivatives. The side chains appear to exploit the presence of the large cavities to incorporate these variant forms, enabling the protein to fold and have some activity. Solution structural and kinetic data suggested that these substitutions had little effect on the overall fold of the protein. Thermodynamic data revealed that the entropic effect of restricting the side chains in the folded protein has an effect on the stability. The variant forms of thioredoxin have different propensities to form dimers despite the limited structural perturbations. Molecular modeling studies allow the conformation of the side chains to be assessed.

Following co-operative formation of secondary and tertiary structure in a single protein module

We have prepared a family of peptide fragments of the 64 amino acid protein chymotrypsin inhibitor (CI2), corresponding to progressive elongation from the N terminus, in order to elucidate the basis of conformational preferences in single-domain proteins and to obtain insights into their conformational pathway. Structural analysis of the fragment comprising the first 50 residues, CI2(1-50), indicates that it is mainly disordered, with patches of hydrophobic residues exposed to the solvent. Structural characterisation of the fragment CI2(1-63) which lacks only the C-terminal glycine, Gly64, shows native-like structure in all regions of the fragment. The study provides insights into the contribution of specific residues to the stability and co-operativity of the intact protein. We define a phiNMR value, derived from chemical shift analysis, which describes the build-up of structure at the level of individual residues (protons). All the macroscopic probes used to study the growth of structure in CI2 on elongation of the chain (circular dichroism, fluorescence and gel filtration) are in agreement with the residue-by-residue description by NMR. It is seen that secondary and tertiary structure build up in parallel in the fragments and show similar structures to those developed in the transition state for folding of the intact protein.

Amplification and expression of the cyclin D1 gene in anal and esophageal squamous cell carcinomas

Cyclin D1 is a cell-cycle regulator and candidate proto-oncogene implicated in the pathogenesis of numerous tumor types. Amplification of the cyclin D1 gene occurs commonly in esophageal squamous cell carcinomas. However, no studies have examined the role of cyclin D1 in anal carcinogenesis. We examined 20 esophageal squamous cell carcinomas and 24 anal carcinomas for cyclin D1 alterations. Protein expression was evaluated by immunohistochemistry using the cyclin DIGM antibody (Novocastra, Newcastle upon Tyne, UK). Cyclin D1 amplification was examined by fluorescent in situ hybridization (FISH), using a cyclin D1 probe obtained from Toshiya Inaba at St. Jude Children's Research Hospital, Memphis, TN. The FISH sections were analyzed using a Leica (Deerfield, IL) confocal microscope. By immunohistochemistry, 75% of esophageal carcinomas showed evidence of cyclin D1 expression. Cyclin D1 amplification was detected by FISH in 65% of esophageal cancers. There was good correlation between cyclin D1 protein expression and gene amplification, although some tumors showed protein overexpression in the absence of gene amplification. Among the 24 anal carcinomas studied, 8% showed weak cyclin D1 immunoreactivity in rare tumor cells. None of the anal tumors showed cyclin D1 amplification. We conclude that cyclin D1 alterations are common in esophageal carcinomas but do not appear to be important in anal carcinogenesis. Immunohistochemical detection of cyclin D1 protein overexpression is a good predictor of cyclin D1 amplification.

Resuscitation of thermally injured patients with oxygen transport criteria as goals of therapy

Resuscitation from shock based on oxygen transport criteria has been widely used in trauma and surgical patients, but has not been examined in thermally injured patients. To study the possible efficacy of this type of resuscitation, the oxygen transport characteristics of burn resuscitation were studied in nine adults, of whom six had inhalation injuries, with a mean burn size of 45% total body surface area and a mean age of 33.4 years, who were resuscitated based on oxygen transport criteria. Pulmonary artery balloon flotation catheters were placed and hemodynamic and oxygen transport parameters (Fick method) were measured hourly for 6 hours. Patients received fluid boluses in addition to resuscitation calculated by the Parkland formula, until the pulmonary artery wedge pressure reached 15 mm Hg, after which dobutamine infusions (5 micrograms/kg/min) were initiated. Cardiac index increased from 2.51 to 6.57 L/min/m2 (p < 0.05), whereas systemic vascular resistance fell from 1534 to 584 dyne sec/cm5 (p < 0.05). Oxygen delivery (DO2I) and oxygen consumption (VO2I) indexes increased significantly during the study period (573 +/- 47 to 1028 +/- 57, and 132 +/- 8 to 172 +/- 16 ml/min/m2, respectively; p < 0.05). VO2I appeared dependent on DO2I at levels of DO2I less than 800 ml/min/m2. In this study, depressed cardiovascular function in patients with burn injuries responded to volume loading and inotropic support much as it does in patients with shock of other etiologies. Whether oxygen transport-based resuscitation is effective in improving survival or the incidence of multiple organ failure is unknown and will need to be evaluated in randomized trials.

A computer-interfaced vertometer system for contact lenses

BACKGROUND

The conventional vertometer (lensometer) is difficult to use for accurate measurement of contact lenses whose back vertex power (BVP) varies across the optic zone. BVPs of multifocal rigid and soft contact lenses have previously been measured using a conventional vertometer incorporating the Scheiner principle, which makes use of two light paths equidistant from the center of the lens.

METHODS

We have developed a computer-based vertometer system based on the Scheiner principle which can be used to produce a profile of BVPs across rigid and soft contact lenses. A computer interface to the vertometer allows rapid acquisition of readings and software-based ray tracing derives in-air dioptric power readings across the optic zone at specific ray heights.

RESULTS

Results are presented for soft and rigid, and spherical and aspheric surface contact lenses.

CONCLUSIONS

The system improves the measurement resolution of a standard vertometer and shows an acceptable level of precision and accuracy for most applications.

Effects of azathioprine withdrawal in kidney recipients with stable function two years after transplant

To assess the effects of azathioprine withdrawal, renal recipients with grafts > 2 yr function (103 study patients) were tapered off azathioprine over a 1-yr period and compared to 69 patients 2 yr after transplant who were not tapered (controls). Of the 103 study patients, 16 (15%) were living-donor transplants and 87 were cadaveric. Of the 69 control patients, 9 (13%) were living related transplants and 60 were cadaveric. The mean HLA match for those tapered was 3.3 Ag and 3.1 Ag for those remaining on azathioprine. Two study patients restarted azathioprine on their own. Age, sex, and cause of renal failure in both groups was similar. Of the 101 study patients remaining, 9 (8.8%) returned to dialysis due to biopsy proven chronic rejection. There were no acute rejection episodes. Six of the 69 control patients (8.7%) also returned to dialysis for the same reason. Of the 92 patients who have completed the taper, 85 have been off azathioprine for six or more months. There was not a significant difference between the mean 12- and 24-month creatinine levels of the study patients (1.6 mg%, 1.7 mg%) and those of the controls (1.5 mg%, 1.8 mg%). The mean 12- and 24-month hematocritis of patients tapered (41.3%, 40.8%) were comparable with patients not tapered (42.3%, 42.8%). Of interest, the mean hematocritis of both study and control patients rose from 28.9% and 33.5%, respectively, to 41.3% and 42.3% 1 yr following entry into the study. The mean 12- and 24-month white blood counts of those tapered (8.9, 8.7) did not differ significantly from those continued on azathioprine (8.8, 8.8). In stable renal transplant patients on triple drug immunosuppression for at least 2 yr, azathioprine can be discontinued, in a tapered protocol, without an increased risk of graft loss or compromise of renal function.

Restructuring dermatology education at Cleveland medical centers affiliated with Case Western Reserve University

We describe our response to the changing needs for dermatologic education and training at Cleveland medical centers affiliated with Case Western Reserve University School of Medicine (CWRU) located in Cleveland, Ohio. Our departmental plan for change is a multifaceted approach that alters the number of dermatology residents we train and also the way we interact with and educate our generalist colleagues. Like many other dermatologists, we have both idealistic and practical reasons for increasing our involvement in interdisciplinary education. One of our primary objectives is maximizing quality of care for dermatologic patients in our community. Traditionally, the majority of skin care in the United States has been provided by nondermatologists, and with the growth of managed care, this proportion is increasing. This has motivated us to increase our medical student teaching activities and to support the American Academy of Dermatology in its current efforts to develop a dermatology core curriculum for students. We should also be involved in the education of generalist physicians, since prior studies have suggested that their knowledge of dermatology needs improvement. Our goals should be both to improve the direct patient care skills of primary care physicians and to teach clinically appropriate referral thresholds. The American Academy of Dermatology has recently issued guidelines for the referral of dermatology patients in managed care settings to help ensure that our specialty has input into this process. In addition, teaching gatekeeper physicians to use appropriate referral criteria is important to many dermatologists in capitated managed care systems who often prefer limited as opposed to unrestricted access to their services.

Illness experiences and health recovery behaviors of patients in southern Appalachia

The purpose of this exploratory study was to gain a better understanding of the influences of Appalachian culture and rural living on illness experiences and health recovery behaviors. The study sample consisted of 257 randomly selected adult patients admitted to medical-surgical units in eight hospitals in West Virginia. Patients completed interviews in the hospital and by phone and in their homes 1 month after hospital discharge. In addition, 203 nurses and 79 physicians completed a values survey and decisional control questions. The triangulation of quantitative and qualitative data suggested that culture, age, gender, and rural residence affected responses to illness and recovery. Traditional values and roles persisted in this population and influenced health behaviors. The findings of this study support the need for culturally sensitive care and for innovative education programs to reduce health risks.

A novel hypothalamic peptide, pituitary adenylate cyclase-activating peptide, regulates the function of rat granulosa cells in vitro

Pituitary adenylate cyclase-activating peptide (PACAP) is a novel peptide that was isolated from ovine hypothalamic tissue on the basis of its ability to stimulate cAMP accumulation in cultured rat pituitary cells. Recently we demonstrated that PACAP can stimulate cAMP accumulation and secretory function in cultured rat Sertoli cells. Since ovarian granulosa cells share many properties with Sertoli cells, we have examined the effect of PACAP (consisting of 38 or 27 amino acid residues) on cultured granulosa cell function. Granulosa cells were obtained from the ovaries of 25-day-old rats implanted with a silastic capsule containing diethylstilbestrol 5 days prior to culture. PACAP 38 (0.1 microM-0.01 pM), both alone and in the presence of the phosphodiesterase inhibitor, methylisobutylxanthine, stimulated cAMP accumulation 4-8-fold with an ED50 of approximately 100 pM. Maximal PACAP 38 or PACAP 27 stimulation of granulosa cell cAMP was significantly greater than that produced by a maximally effective concentration of FSH. Because PACAP 38 and 27 have 68% sequence homology with vasoactive intestinal peptide (VIP), and since VIP stimulates granulosa cell cAMP accumulation and estradiol and progesterone secretion, we examined the possibility that PACAP could be acting via the VIP receptor. VIP stimulated cAMP only at concentrations of 10 nM or greater, whereas the PACAP stimulation was evident at 10 pM. Moreover, only one of three potent VIP antagonists inhibited VIP stimulation of cAMP accumulation, and only at 1 microM or greater. This VIP antagonist did not inhibit PACAP 38 action at 2000-fold excess concentration. Interestingly PACAP 38 was more effective than PACAP 27 with regard to steroid secretion and the ability to induce LH responsiveness. PACAP and VIP stimulation of granulosa cell cAMP accumulation or estradiol or progesterone secretion was not additive. Thus, these data support the hypothesis that granulosa cells have specific PACAP 38 receptors and that VIP acts via these receptors. In addition, PACAPs 38 and 27 are more potent stimulators of cAMP accumulation in luteinized granulosa cells than LH. These results both pre- and postovulation, along with previous data indicating that the PACAPs are found in the ovaries, suggest a role for PACAP in the regulation of ovarian function.

Determination of benzidine, N-acetylbenzidine, and N,N'-diacetylbenzidine in human urine by capillary gas chromatography/negative ion chemical ionization mass spectrometry

We report an isotope dilution mass spectrometry method using capillary gas chromatography/negative ion chemical ionization to quantitate urine concentrations of benzidine (BZ) and of its acetylated metabolites N-acetylbenzidine (ABZ) and N,N'-diacetylbenzidine (DABZ). Urine samples were purified by solid-phase extraction columns, reduced with LiAlH4/THF, and derivatized with pentafluoropropionic anhydride. The derivatives were measured by selected ion monitoring relative to deuterium-labeled internal standards. A detection limit as low as 0.5, 0.8, and 1.5 ppt for BZ, ABZ, and DABZ, respectively, can easily be achieved. Urinary concentrations of ABZ substantially exceed those of either BZ or of DABZ in workers exposed to BZ or BZ-based dyes. This method has been successfully used to measure BZ, ABZ, and DABZ in 1.0-ml urine samples collected from workers involved in manufacturing BZ and BZ-based dyes. The method should be applicable to the measurement of other aromatic amines and their acetylated metabolites.

The association among gastric mucosal pH, endotoxemia, and low systemic vascular resistance after cardiopulmonary bypass

OBJECTIVE

Previously, it was found that a number of patients suffer a "low systemic vascular resistance syndrome" after cardiopulmonary bypass, and this was hypothesized to be secondary to endotoxemia, resulting from intestinal ischemia during bypass.

DESIGN

Prospective cohort.

SETTING

University teaching hospital.

PARTICIPANTS

Thirty-two patients undergoing cardiac surgery.

INTERVENTIONS

A number of variables relating to adequacy of tissue perfusion were measured at seven time periods perioperatively: cardiac output, systemic vascular resistance, oxygen delivery and consumption, oxygen extraction ratio, gastric mucosal pH, serum lactate, and endotoxin levels.

MEASUREMENTS AND MAIN RESULTS

Investigators could not find any association between systemic vascular resistance and mucosal pH or endotoxin levels after bypass. There were significant changes in oxygen flux and extraction ratio (p < 0.001) as well as serum lactate (p < 0.001). There was no significant change in endotoxin levels or mucosal pH. The systemic vascular resistance at 6 hours postbypass could be predicted from the vascular resistance reading at 1 hour postbypass by a regression equation. A significant correlation between systemic vascular resistance and mixed venous oxygen was found at 4 and 6 hours postbypass (p < 0.01) as well as with oxygen extraction (p < 0.01). There was a negative correlation between mucosal pH and serum lactate, particularly at 6 hours postbypass (p < 0.01). There was no correlation between mucosal pH and endotoxin levels, oxygen flux, or cardiac output.

CONCLUSIONS

The investigators therefore could not find any evidence that intestinal ischemia during bypass, as measured by gastric mucosal pH, predisposes to endotoxemia, or low systemic vascular resistance after cardiac surgery.

Towards the complete structural characterization of a protein folding pathway: the structures of the denatured, transition and native states for the association/folding of two complementary fragments of cleaved chymotrypsin inhibitor 2. Direct evidence for a nucleation-condensation mechanism

BACKGROUND

Single-module proteins, such as chymotrypsin inhibitor 2 (CI2), fold as a single cooperative unit. To solve its folding pathway, we must characterize, under conditions that favour folding, its denatured state, its transition state, and its final folded structure. To obtain a "denatured state' that can readily be thus characterized, we have used a trick of cleaving CI2 into two complementary fragments that associate and fold in a similar way to intact protein.

RESULTS

Fragment CI2(1-40)-which contains the sequence of the single alpha-helix, spanning residues 12-24-and CI2(41-64), and mutants thereof, were analyzed by NMR spectroscopy, the transition state for association/folding was characterized by the protein engineering method, and the structure of the complex was solved by NMR and X-ray crystallography. Both isolated fragments are largely disordered. The transition state for association/folding is structured around a nucleus of a nearly fully formed alpha-helix, as is the transition state for the folding of intact CI2, from residues Ser12 to Leu21, Ala16, a residue from the helix whose sidechain is buried in the hydrophobic core, makes interactions with Leu49 and Ile57 in the other fragment. Ala16 makes its full interaction energy in the transition state for the association/folding reaction, just as found during the folding of the intact protein.

CONCLUSIONS

The specific contacts in the transition state from a nucleus that extends from one fragment to the next, but the nucleus is only "flickeringly' present in the denatured state. This is direct evidence for the nucleation-condensation mechanism in which the nucleus is only weakly formed in the ground state and develops in the transition state. The low conformational preferences in the denatured state are not enough to induce significant local secondary structure, but are reinforced by tertiary interactions during the rapid condensation around the nucleus.

Hematopoietic transcriptional regulation by the myeloid zinc finger gene, MZF-1

Transcriptional regulators control much of hematopoiesis. One such transcriptional regulator is the myeloid zinc finger gene MZF-1. MZF-1 has been localized to the telomere of chromosome 19q, where a large number of related zinc finger genes reside. It has been found to be essential in granulopoiesis. It is a bi-functional transcriptional regulator, repressing transcription in non-hematopoietic cells, and activating transcription in cells of hematopoietic origins. Its consensus DNA binding site has been isolated, and sites in several promoters of myeloid-specific genes, such as CD34, lactoferrin, and myeloperoxidase, have been defined. In co-transfection experiments MZF-1 has been found to regulate transcription from the CD34 promoter.

Perturbed pKA-values in the denatured states of proteins

We show in this study that the ionisation equilibria of denatured proteins in pure water are inconsistent with the "fully-unfolded" conformation being an extended coil where the residues are isolated from one another by the intervening solvent. The effects of acid and salt on the stability of the barley chymotrypsin inhibitor 2 (CI2) were investigated and the pKA-values of all carboxylate residues in the native protein were determined by NMR. A comparison of the experimentally determined pH-dependence of the protein stability and that calculated using observed pKA-values in the native state, reveals that the pKA-values in the denatured state are, on average, 0.3 pH units lower than those of model compounds. An increase in ionic strength eliminates these pKA shifts in the denatured state. This shows that there are electrostatic interactions in the denatured state of CI2. Since previous studies on barnase and the Ovomucoid Third Domain also report anomalous titration behaviours of the denatured states, it appears that perturbed pKA-values in the denatured state is a general phenomenon, indicating that the unfolded conformation in pure water is a fairly compact species. In addition, we used a mutational approach to determine the pKA-values of a carboxylate group in both the native and denatured states. The pKA-value in the native state obtained by this method is in precise agreement with that obtained by NMR.

The myeloid zinc finger gene, MZF-1, regulates the CD34 promoter in vitro

MZF-1 is a C2H2 zinc finger gene encoding a putative transcriptional regulator of myeloid differentiation. The MZF-1 protein contains 13 C2H2 zinc fingers arranged in bipartite DNA binding domains containing zinc fingers through 4 and, in the carboxy-terminus, 5 through 13. We previously identified the DNA consensus binding site recognized by the two DNA binding domains. To assess the transcription regulatory function of MZF-1, the full-length MZF-1 coding region was fused to the DNA binding domain of the yeast transactivator GAL4. The expression vector was cotransfected with the chloramphenicol acetyl transferase (CAT) reporter gene regulated by the thymidine kinase promoter containing GAL4 DNA binding sites into NIH 3T3, 293, K562, and Jurkat cell lines. MZF-1 represses CAT reporter gene expression via GAL4 binding sites in the nonhematopoietic cell lines NIH 3T3 and 293. In contrast, MZF-1 activates CAT reporter gene expression in the hematopoietic cell lines K562 and Jurkat. The MZF-1 binding sites are present in the promoters of several genes expressed during myeloid differentiation, including the CD34 promoter. MZF-1 transcriptional regulation of this physiologically relevant promoter was assessed in both hematopoietic and nonhematopoietic cell lines. Recombinant MZF-1 protein specifically binds to the consensus binding sites in the CD34 promoter in mobility shift assays. MZF-1 expression vectors were cotransfected with the luciferase reporter plasmids regulated by the CD34 promoter into both nonhematopoietic and hematopoietic cell lines. As with the heterologous DNA binding domain, MZF-1 represses reporter gene expression in nonhematopoietic cell lines and activates expression in hematopoietic cell lines. Activation of CD34 expression in hematopoietic cell lines is dependent on the presence of intact MZF-1 binding sites. The cell type-specific regulation of the CD34 promoter by MZF-1 suggests the presence of tissue-specific regulators/adapters or differential MZF-1 modifications that determine MZF-1 transcriptional regulatory function.

Physical working capacity after acute myocardial infarction in patients with low ejection fraction and effect of captopril

Previous studies after acute myocardial infarction (AMI) have reported conflicting results on the effects of angiotensin-converting enzyme inhibition on physical working capacity. In an effort to provide more insight into this subject, we examined the effects of captopril on working capacity of patients who had low ejection fractions but no congestive heart failure after AMI. One hundred sixty-six participants were recruited from 5 centers after randomization to either captopril or placebo for the Survival and Ventricular Enlargement study. Upright cycle ergometer tests were performed with continuous measurements of respiratory gases at 4, 12, and 24 months after AMI. Our study concurs with 2 of 3 previous post-AMI studies and supports the conclusion that working capacity is not affected by angiotensin-converting enzyme inhibition at 4 or 12 months after AMI in patients without congestive heart failure. In addition, no significant effect of captopril was noted at 24 months after AMI. Peak oxygen uptake tended to decrease between 12 and 24 months in the placebo group by an average (+/- SD) of -22 +/- 322 ml/min (n = 66), but to increase in the captopril group (+62 +/- 289, n = 57), a difference that was significant (Mann-Whitney chi-square, p = 0.02). This post-hoc observation suggests that a late beneficial effect may have been masked by inadequate study duration. Known benefits of captopril appear not to include an increase in working capacity within the first 24 months after AMI.

Factors affecting ED length-of-stay in surgical critical care patients

To determine what patient characteristics are associated with prolonged emergency department (ED) length-of-stay (LOS) for surgical critical care patients, the charts of 169 patients admitted from the ED directly to the operating room (OR) or intensive care unit (ICU) during a 6-week period in 1993 were reviewed. The ED record was reviewed for documentation of factors that might be associated with prolonged ED LOS, such as use of computed tomographic (CT), radiology special procedures, and the number of plain radiographs and consultants. ED LOS was considered to be the time from triage until a decision was made to admit the patient. Using a Cox proportional hazards model, use of CT and special procedures were the strongest independent predictors of prolonged ED length-of-stay. The number of plain radiographs and consultants had only a minimal effect. Use of a protocol-driven trauma evaluation system was associated with a shorter ED LOS. In addition to external factors that affect ED overcrowding, ED patient management decisions may also be associated with prolonged ED length-of-stay. Such ED-based factors may be more important in surgical critical care patients, whose overall ED LOS is affected more by the length of the ED work-up rather than the time spent waiting for a ICU bed or operating suite.

Microfluctuations of steady-state accommodation and the cardiopulmonary system

The relationship between variations in steady-state accommodation (microfluctuations) and rhythmic cycles in cardiopulmonary system was investigated. As previously reported, vascular pulse frequency was consistently correlated with the high frequency component of steady-state accommodation microfluctuations. In a new finding, respiration rate and an associated cycle in the instantaneous pulse rate also showed a correlation with a low frequency component of the accommodation power spectra. This apparent coherence between respiration frequency and an accommodation low frequency component was maintained during rapid breathing and was evident at the expected frequency during regulated breathing patterns. This association may reflect the direct influence of the autonomic nervous system upon the ciliary muscle or may be caused by the modulation of intraocular pulse by the autonomic nervous system.