Mutant presenilins of Alzheimer's disease increase production of 42-residue amyloid beta-protein in both transfected cells and transgenic mice

The mechanism by which mutations in the presenilin (PS) genes cause the most aggressive form of early-onset Alzheimer's disease (AD) is unknown, but fibroblasts from mutation carriers secrete increased levels of the amyloidogenic A beta 42 peptide, the main component of AD plaques. We established transfected cell and transgenic mouse models that coexpress human PS and amyloid beta-protein precursor (APP) genes and analyzed quantitatively the effects of PS expression on APP processing. In both models, expression of wild-type PS genes did not alter APP levels, alpha- and beta-secretase activity and A beta production. In the transfected cells, PS1 and PS2 mutations caused a highly significant increase in A beta 42 secretion in all mutant clones. Likewise, mutant but not wildtype PS1 transgenic mice showed significant overproduction of A beta 42 in the brain, and this effect was detectable as early as 2-4 months of age. Different PS mutations had differential effects on A beta generation. The extent of A beta 42 increase did not correlate with presenilin expression levels. Our data demonstrate that the presenilin mutations cause a dominant gain of function and may induce AD by enhancing A beta 42 production, thus promoting cerebral beta-amyloidosis.

Systematic review of preoperative, intraoperative and postoperative risk factors for colorectal anastomotic leaks

BACKGROUND

Anastomotic leak (AL) represents a dreaded complication following colorectal surgery, with a prevalence of 1-19 per cent. There remains a lack of consensus regarding factors that may predispose to AL and the relative risks associated with them. The objective was to perform a systematic review of the literature, focusing on the role of preoperative, intraoperative and postoperative factors in the development of colorectal ALs.

METHODS

A systematic review was performed to identify adjustable and non-adjustable preoperative, intraoperative and postoperative factors in the pathogenesis of AL. Additionally, a severity grading system was proposed to guide treatment.

RESULTS

Of 1707 papers screened, 451 fulfilled the criteria for inclusion in the review. Significant preoperative risk factors were: male sex, American Society of Anesthesiologists fitness grade above II, renal disease, co-morbidity and history of radiotherapy. Tumour-related factors were: distal site, size larger than 3 cm, advanced stage, emergency surgery and metastatic disease. Adjustable risk factors were: smoking, obesity, poor nutrition, alcohol excess, immunosuppressants and bevacizumab. Intraoperative risk factors were: blood loss/transfusion and duration of surgery more than 4 h. Stomas lessen the consequences but not the prevalence of AL. In the postoperative period, CT is the most commonly used imaging tool, with or without rectal contrast, and a C-reactive protein level exceeding 150 mg/l on day 3-5 is the most sensitive biochemical marker. A five-level classification system for AL severity and appropriate management is presented.

CONCLUSION

Specific risk factors and their potential correction or indications for stoma were identified. An AL severity score is proposed to aid clinical decision-making.

Transgenic mice expressing hamster prion protein produce species-specific scrapie infectivity and amyloid plaques

Three transgenic mouse lines designated Tg 69, 71, and 81 were produced harboring a Syrian hamster (Ha) prion protein (PrP) gene; all expressed the cellular HaPrP isoform in their brains. Inoculation of Tg 81 mice or hamsters with Ha prions caused scrapie in integral of 75 days; nontransgenic control mice failed to develop scrapie after greater than 500 days. Tg 71 mice inoculated with Ha prions developed scrapie in integral of 170 days. Both Tg 71 and Tg 81 mice exhibited spongiform degeneration and reactive astrocytic gliosis, and they produced the scrapie HaPrP isoform in their brains. Tg 81 brains also showed HaPrP amyloid plaques characteristic of Ha scrapie and contained integral of 10(9) ID50 units of Ha prions based on Ha bioassays. Our findings argue that the PrP gene modulates scrapie susceptibility, incubation times, and neuropathology; furthermore, they demonstrate synthesis of infectious scrapie prions programmed by a recombinant DNA molecule.

Bipolar illness in adolescents with major depression: clinical, genetic, and psychopharmacologic predictors in a three- to four-year prospective follow-up investigation

Sixty adolescents, aged 13 to 16 years, hospitalized for major depression were studied prospectively, for three to four years to determine the utility of clinical, genetic, and pharmacologic response variables in predicting a bipolar course of illness. Bipolar outcome was observed in 20% of the cohort. Statistical analyses showed that bipolarity was predicted by (1) a depressive symptom cluster comprising rapid symptom onset, psychomotor retardation, and mood-congruent psychotic features; (2) a "loading" of affective disorder in the family pedigree, a family history of bipolar illness, and the presence of illness in three successive generations of the pedigree; and (3) pharmacologically induced hypomania. All predictors were shown to have high specificity for bipolar outcome, whereas pharmacologic hypomania and symptom cluster permitted the highest confidence of prediction, 100% and 80%, respectively. Even in juvenile depression, careful attention to clinical and biologic variables may aid in the predictive differentiation of meaningful diagnostic subtypes.

Management of the infected median sternotomy wound with muscle flaps. The Emory 20-year experience

OBJECTIVE

The purpose of the study is to define those patient variables that contribute to morbidity and mortality of median sternotomy wound infection and the results of treatment by debridement and closure by muscle flaps.

BACKGROUND

Infection of the median sternotomy wound after open heart surgery is a devastating complication associated with significant mortality. Twenty years ago, these wounds were treated with either open packing or antibiotic irrigation, with a mortality approaching 50% in some series. In 1975, the authors began treating these wounds with radical sternal debridement followed by closure using muscle or omental flaps. The mortality of sternal wound infection has dropped to < 10%.

METHODS

The authors' total experience with 409 patients treated over 20 years is described in relation to flap choices, hospital days after sternal wound closure, and incidence rates of morbidity and mortality. One hundred eighty-six patients treated since January 1988 were studied to determine which patient variables had impact on rates of flap closure complications, recurrent sternal wound infection, or death. Variables included obesity, history of smoking, hypertension, diabetes, poststernotomy septicemia, internal mammary artery harvest, use of intra-aortic balloon pump, and perioperative myocardial infarction and were analyzed using chi square tests. Fisher's exact tests, and multivariable logistic regression analysis.

RESULTS

The mortality rate over 20 years was 8.1% (33/49). Additional procedures for recurrent sternal wound infection were necessary in 5.1% of patients. Thirty-one patients (7.6%) required treatment for hematoma, and 11 patients (2.7%) required hernia repair. Among patients treated since 1988, variables strongly associated with mortality were septicemia (p < 0.00001), perioperative myocardial infarction (p = 0.006), and intra-aortic balloon pump (p = 0.0168). Factors associated with wound closure complications were intra-aortic balloon pump (p = 0.0287), hypertension (p = 0.0335), and history of smoking (p = 0.0741). Factors associated with recurrent infection were history of sternotomy (p = 0.008) and patients treated for sternal wound infection from 1988 to 1992 (p = 0.024). Mean hospital stay after sternal wound reconstruction declined from 18.6 days (1988-1992) to 12.4 days (1993-1996) (p = 0.005). To clarify management decisions of these difficult cases, a classification of sternal wound infection is presented.

CONCLUSIONS

Using the principles of sternal wound debridement and early flap coverage, the authors have achieved a significant reduction in mortality after sternal wound infection and have reduced the mean hospital stay after sternal wound closure of these critically ill patients. Further reductions in mortality will depend on earlier detection of mediastinitis, before onset of septicemia, and ongoing improvements in the critical care of patients with multisystem organ failure.

Congruence of diagnoses 2 years after a first-admission diagnosis of psychosis

BACKGROUND

Diagnostic changes may reflect evolution of an illness, emergence of newly disclosed information, or unreliability of assessment. This study evaluates the stability of research diagnoses in a heterogeneous first-admission sample with psychosis.

METHODS

A group of 547 subjects initially diagnosed with a psychosis were reassessed 6 and 24 months after enrollment. The DSM-IV consensus diagnoses were formulated by psychiatrists blind to previous research diagnoses. The analysis focuses on agreement over time and the effects of demographic, family history, and clinical variables on the shift from a nonschizophrenia diagnosis to schizophrenia.

RESULTS

Seventy-two percent of 6- and 24-month diagnoses were congruent. The most temporally consistent 6-month categories were schizophrenia (92%), bipolar disorder (83%), and major depression (74%); the least stable were psychosis not otherwise specified (44%), schizoaffective disorder (36%), and brief psychosis (27%). The most frequent shift in diagnosis at 24 months was to schizophrenia spectrum (n=45). These 45 subjects had a similar illness course after 6 months as the 171 subjects in this category at both assessments, but their prior clinical functioning was better. Risk factors predicting change to a schizophrenia spectrum diagnosis include facility variables (schizophrenia diagnosis, longer stays, and given antipsychotic medication on hospital discharge); prehospital features (psychotic > or =3 months before admission, poorer adolescent adjustment, lifetime substance disorder); and negative symptoms.

CONCLUSIONS

Changes in diagnosis, particularly to schizophrenia, are mostly attributable to the evolution of the illness. Rigid adherence to DSM-IV requirements may have led to underdiagnosis of schizophrenia. The findings support the need for a longitudinally based diagnostic process in incidence samples.

Measurement of the proportion of free to total prostate-specific antigen improves diagnostic performance of prostate-specific antigen in the diagnostic gray zone of total prostate-specific antigen

OBJECTIVES

This study examined the clinical significance of non-complexed (free) prostate-specific antigen (PSA) in the differential diagnosis of prostate cancer with an emphasis on patients with total PSA values between 4.0 and 10.0 ng/mL (the diagnostic gray zone).

METHODS

Serum samples were obtained from three specimen banks. Patient samples consisted of 55 untreated histologically confirmed primary cancer, 62 men with untreated benign prostatic disease histologically confirmed by 6 negative sextant biopsies, and 64 asymptomatic healthy male controls with normal digital rectal examinations and PSA values less than 4.0 ng/mL. All patients were between the ages of 50 and 75 years. Total PSA levels were determined using the PA immunoassay performed on the TOSOH AIA-1200 automated immunoassay instrument. Free PSA levels were determined using a monoclonal-polyclonal antibody sandwich radioimmunoassay. The proportion of free to total PSA was calculated by dividing the patient's free PSA value by the total PSA value.

RESULTS

When all subjects were included, both total PSA and the proportion of free to total PSA significantly differentiated between patients with prostate cancer and patients with benign histologic conditions (P < 0.0001). However, in men with total PSA values between 4.0 and 10.0 ng/mL, the proportion of free to total PSA significantly differentiated between patients with benign and malignant histologic conditions (P = 0.0004), whereas the total PSA did not (P = 0.13). Among this subgroup of patients, the analysis of sensitivity and specificity showed that the proportion of free to total PSA had a clearly higher specificity compared with that of the total PSA at the same level of sensitivity.

CONCLUSIONS

Measurement of the free PSA level in a patient's serum and calculation of the proportion of free to total PSA enhances the ability to distinguish benign histologic conditions from cancer while retaining high sensitivity for detecting cancer in men who present with total PSA levels between 4.0 and 10.0 ng/mL. A large-scale population-based study is currently in progress to confirm this preliminary finding.

Anterior cervical pseudarthrosis. Natural history and treatment

STUDY DESIGN

A retrospective study of long-term clinical outcomes in 48 patients with pseudarthroses after anterior cervical discectomy and fusion.

OBJECTIVES

To determine the natural history, risk factors, and treatment outcomes in a large population with documented pseudarthrosis after anterior cervical discectomy and fusion.

SUMMARY OF BACKGROUND DATA

Recent reports suggest that pseudarthrosis after anterior cervical discectomy and fusion adversely affects clinical outcome. Little data regarding cervical pseudarthroses have been published, and conclusions have been drawn from reports with small patient populations and short-term follow-up periods.

METHODS

Forty-eight patients with radiographically documented pseudarthrosis after anterior cervical discectomy and fusion were studied. Patients were examined and radiographs made at regular intervals (mean follow-up, 66 months). Clinical results were based on patients' assessment of pain, prescription drug use, activity level and Odom's criteria. Clinical outcomes in patients who underwent surgical repair of the pseudarthrosis are reported.

RESULTS

Of the 48 patients, 32 (67%) with pseudarthroses were symptomatic at latest follow-up or at the time of further surgery. Of the 32 patients, 9 had a symptom-free period of at least 2 years after the anterior cervical discectomy and fusion before redeveloping cervical symptoms after a traumatic episode. Of 48 patients with pseudarthroses, 16 (33%) remained asymptomatic at a mean of 5.1 years after anterior cervical discectomy and fusion. A younger age at the time of anterior cervical discectomy and fusion increased the likelihood of the pseudarthrosis becoming symptomatic. After multiple level anterior cervical discectomy and fusion, the caudal-most operated level accounted for 82% of the pseudarthroses. Sixteen patients had an anterior repair of the pseudarthrosis, and fusion was achieved in 14. Six patients underwent posterior pseudarthrosis repair, and all healed. In patients in whom fusion was achieved with a second cervical operation, the results were excellent in 19 and good in 1.

CONCLUSION

A pseudarthrosis after anterior cervical discectomy and fusion is frequently associated with a poor clinical outcome. Surgical repair of the pseudarthrosis with an anterior or posterior approach seems to have a high likelihood of a successful clinical outcome.

GABAB-mediated rescue of altered excitatory-inhibitory balance, gamma synchrony and behavioral deficits following constitutive NMDAR-hypofunction

Reduced N-methyl-D-aspartate-receptor (NMDAR) signaling has been associated with schizophrenia, autism and intellectual disability. NMDAR-hypofunction is thought to contribute to social, cognitive and gamma (30-80 Hz) oscillatory abnormalities, phenotypes common to these disorders. However, circuit-level mechanisms underlying such deficits remain unclear. This study investigated the relationship between gamma synchrony, excitatory-inhibitory (E/I) signaling, and behavioral phenotypes in NMDA-NR1(neo-/-) mice, which have constitutively reduced expression of the obligate NR1 subunit to model disrupted developmental NMDAR function. Constitutive NMDAR-hypofunction caused a loss of E/I balance, with an increase in intrinsic pyramidal cell excitability and a selective disruption of parvalbumin-expressing interneurons. Disrupted E/I coupling was associated with deficits in auditory-evoked gamma signal-to-noise ratio (SNR). Gamma-band abnormalities predicted deficits in spatial working memory and social preference, linking cellular changes in E/I signaling to target behaviors. The GABA(B)-receptor agonist baclofen improved E/I balance, gamma-SNR and broadly reversed behavioral deficits. These data demonstrate a clinically relevant, highly translatable neural-activity-based biomarker for preclinical screening and therapeutic development across a broad range of disorders that share common endophenotypes and disrupted NMDA-receptor signaling.

Insulin resistance and substrate utilization in human endotoxemia

Infection results in a state of insulin resistance, but the pathogenesis is poorly understood. Intravenous administration of bacterial lipopolysaccharide (LPS) has been used to mimic the febrile and systemic inflammatory responses to infection, but it is unclear whether LPS induces insulin resistance in man. To investigate the effects of LPS on insulin sensitivity and substrate utilization, we administered, in paired cross-over studies, either 20 U/kg Escherichia coli endotoxin or saline control to healthy volunteers (n = 6) 120 min after the start of a 10-h euglycemic hyperinsulinemic clamp (insulin infusion rate, 80 mU/m2 x min). LPS induced a fever, tachycardia, and mild arterial hypotension. Glucose utilization increased abruptly 120 min after LPS administration (+64.1+/-12.0%; P < 0.003), but then declined progressively, and insulin resistance was evident by 420 min (+1.9+/-3.5%; P < 0.05). The reduction in glucose utilization, like that observed in sepsis, was related to impaired nonoxidative glucose disposal and not abnormal glucose oxidation. The cortisol and GH responses to LPS were of sufficient duration and magnitude to explain the insulin resistance. LPS administration results in metabolic responses very similar to those observed in sepsis and could provide a useful model for the study of insulin resistance in human critical illness.

Randomized clinical trial of the effects of immediate enteral nutrition on metabolic responses to major colorectal surgery in an enhanced recovery protocol

BACKGROUND

The effects of immediate postoperative enteral nutrition on postoperative nitrogen balance and insulin resistance were studied in patients subjected to an enhanced-recovery protocol.

METHODS

Eighteen patients undergoing major colorectal surgery in an enhanced-recovery protocol were randomized to immediate postoperative enteral feeding for 4 days with either complete or hypocaloric nutrition. Nitrogen balance and changes in glucose kinetics, substrate utilization (indirect calorimetry) and insulin sensitivity (hyperinsulinaemic-euglycaemic clamp) were measured. Values are mean(s.e.m.).

RESULTS

Mean postoperative urinary nitrogen losses were low (10.7(1.0) versus 10.5(0.7) g per day for complete versus hypocaloric nutrition) and insulin resistance was insignificant (-20(7) versus -27(11) per cent), with no difference between groups. Complete enteral feeding was given without hyperglycaemia (blood glucose concentration 5.8(0.4) versus 5.0(0.4) mmol/l) and resulted in nitrogen balance (+0.1(0.8) versus -12.6(0.6) g nitrogen per day; P < 0.001).

CONCLUSION

This enhanced-recovery protocol was associated with minimal postoperative insulin resistance and nitrogen losses after surgery. Immediate postoperative enteral nutrition was provided without hyperglycaemia and resulted in nitrogen balance.

Fistuloclysis can successfully replace parenteral feeding in the nutritional support of patients with enterocutaneous fistula

Background

Use of total parenteral nutrition (TPN) in patients with acute intestinal failure due to enteric fistulation might be avoided if a simpler means of nutritional support was available. The aim of this study was to determine whether feeding via an intestinal fistula (fistuloclysis) would obviate the need for TPN.

Methods

Fistuloclysis was attempted in 12 patients with jejunocutaneous or ileocutaneous fistulas with mucocutaneous continuity. Feeding was achieved by inserting a gastrostomy feeding tube into the intestine distal to the fistula. Infusion of enteral feed was increased in a stepwise manner, without reinfusion of chyme, until predicted nutritional requirements could be met by a combination of fistuloclysis and regular diet, following which TPN was withdrawn. Energy requirements and nutritional status were assessed before starting fistuloclysis and at the time of reconstructive surgery.

Results

Fistuloclysis replaced TPN entirely in 11 of 12 patients. Nutritional status was maintained for a median of 155 (range 19–422) days until reconstructive surgery could be safely undertaken in nine patients. Two patients who did not undergo surgery remained nutritionally stable over at least 9 months. TPN had to be recommenced in one patient. There were no complications associated with fistuloclysis.

Conclusion

Fistuloclysis appears to provide effective nutritional support in selected patients with enterocutaneous fistula.

Prevalence and severity of substance use disorders and onset of psychosis in first-admission psychotic patients

BACKGROUND

Past studies have found inconsistent evidence that substance use disorders are related to earlier onset of schizophrenia or more severe symptoms. This study examines prevalence and severity of current substance use disorders and onset of psychotic illness in a multi-facility sample.

METHODS

Data are from the Suffolk County Mental Health Project, an epidemiological study of first admission psychosis. The SCID and instruments measuring symptomatology, personality and background characteristics were administered. Respondents were stratified into three groups: (a) no life-time substance diagnosis; (b) in remission or reporting current mild use at admission; and (c) current moderate-severe substance abuse at admission.

RESULTS

Using the SCID severity rating, 17.4% of males and 6.2% of the females had moderate or severe current substance abuse, while 41.5% of males and 68.2% of females had no lifetime substance diagnosis. In almost all cases categorized as moderate-severe, the substance diagnosis predated onset of psychosis. Females categorized as moderate-severe have an earlier age of onset of psychosis than did females in the other groups. There were only slight differences in symptom severity among the groups but more marked antisocial behaviour in the moderate-severe group. Variables discriminating the moderate-severe from non-abuse groups were BPRS thought disturbance, adult anti-social behaviour and current cigarette smoking for males and adult anti-social behaviour and child-teen antisocial behaviour for females.

CONCLUSIONS

Severity of substance abuse does not appear to be a pivotal correlate of the early features of psychotic illness.

The measurement of craving in cocaine patients using the Minnesota Cocaine Craving Scale

Drug craving is an irresistible urge that compels drug-seeking behavior, and which often accounts for relapse among treated cocaine users. A cocaine craving scale that has proven reliable and practical in clinical treatment research with cocaine-using subjects is presented. It assesses intensity, frequency, and duration of this entirely subjective phenomenon. Data from 234 scales completed by 35 patients in treatment showed that craving for cocaine was of variable intensity, experienced relatively few times per day (zero to two), and of short duration (less than 20 minutes). Internal consistency among the three scales was robust, shown by a standardized item alpha of .826. The use of this scale should allow for each component of craving to be studied separately.

Glutamine deprivation facilitates tumour necrosis factor induced bacterial translocation in Caco-2 cells by depletion of enterocyte fuel substrate

BACKGROUND AND AIMS

Factors that induce luminal bacteria to cross the intestinal epithelium following injury remain poorly defined. The aim of this study was to investigate the interaction between glutamine metabolism, energy supply, and inflammatory mediators in determining the translocation of non-pathogenic bacteria across cultured enterocytes.

METHODS

The effect of tumour necrosis factor alpha (TNF-alpha) on translocation of Escherichia coli C25 across Caco-2 epithelial monolayers was studied in the presence of products and inhibitors of glutamine metabolism. Simultaneous measurements of transepithelial electrical resistance (TEER) and flux of lucifer yellow were used to assess effects on the paracellular pathway. Lactate dehydrogenase release was used to monitor enterocyte integrity. Imaging of monolayers in these experimental conditions was undertaken with transmission electron microscopy.

RESULTS

Exposure to basolateral TNF-alpha (20 ng/ml) for six hours induced translocation of E coli across Caco-2 but only if accompanied by simultaneous glutamine depletion (p<0.01). Translocation was inhibited by addition of glutamine for two hours (p<0.01) but not by an isonitrogenous mixture of non-glutamine containing amino acids. Inhibition of glutamine conversion to alpha-ketoglutarate, but not blockade of glutathione or polyamine synthesis, also induced translocation in the presence of TNF-alpha. Manipulations that induced bacterial translocation were associated with a marked reduction in enterocyte ATP levels. No effect of these treatments on paracellular permeability or lactate dehydrogenase release was observed. Conditions in which translocation occurred were associated with the presence of bacteria within enterocyte vacuoles but not the paracellular space.

CONCLUSIONS

In inflammatory conditions, the availability of glutamine as an enterocyte fuel substrate is essential for the preservation of a functional barrier to microorganisms. In conditions of acute glutamine depletion, cytokine mediated bacterial translocation appears to be primarily a transcellular process.

Using proportions of free to total prostate-specific antigen, age, and total prostate-specific antigen to predict the probability of prostate cancer

OBJECTIVES

This study was undertaken to define the probability of prostate cancer as a function of the proportion of free to total prostate-specific antigen (FTPSA), total PSA, and age for those patients with total PSA levels between 2.5 and 20.0 ng/mL.

METHODS

Prebiopsy serums were obtained from 428 untreated patients (165 malignant, 263 benign) who had undergone sextant six-core biopsy. Each patient had no prior history of prostate cancer and a prebiopsy total PSA value between 2.5 and 20.0 ng/mL. Total PSA levels were determined using the PA immunoassay performed on the TOSOH AIA-1200 automated immunoassay instrument. Free PSA levels were determined using a monoclonal-polyclonal antibody sandwich radioimmunoassay.

RESULTS

In men with total PSA values between 2.5 and 20.0 ng/mL, the FTPSA significantly differentiated between patients with benign and malignant histologic states. Log linear modeling indicated distinct differences in the risk for cancer as a function of FTPSA, total PSA, and age. The highest probability for cancer was observed in men greater than 70 years of age who had a FTPSA less than 7% and total PSA more than 10.0 ng/mL. Conversely, the lowest probability for cancer was observed in patients less than 60 years of age who had a FTPSA more than 25% and a total PSA less than 4 ng/mL.

CONCLUSIONS

The probability that prostate cancer will be found on biopsy has a marked gradient that is associated with age, total PSA, and FTPSA. The extreme ends of FTPSA of less than 7% and more than 25% are diagnostic for prostate cancer and benign prostatic disease, respectively.

Partially purified white bean amylase inhibitor reduces starch digestion in vitro and inactivates intraduodenal amylase in humans

Whether commercial, bean-derived alpha-amylase inhibitor preparations failed to decrease starch digestion in humans because of insufficient antiamylase activity, destruction by gastrointestinal secretions, or decreased activity in the presence of starch is unknown. We used a simple partial purification procedure to markedly concentrate the inhibitor (sixfold to eightfold by total protein content, and 30-40-fold by dry weight). Compared with a commercial preparation and crude bean extract, this partially purified inhibitor inactivated intraduodenal, intraileal, and salivary amylase in vitro faster and more completely (p less than 0.001); its specific activity was not affected by exposure to gastric juice and was only minimally reduced by duodenal juice. Whereas the rate of amylase inhibition by inhibitor was markedly slowed in the presence of nondietary liquid starch, dietary solid starch had only a minimal effect. Consequently, the partially purified inhibitor had no effect on liquid starch digestion, but decreased in vitro digestion of dietary starch in a dose-dependent manner (p less than 0.001). Perfusion of the partially purified inhibitor (2.0, 3.5, or 5.0 mg/ml at 5 ml/min) into the duodenum of humans rapidly inhibited greater than 94%, greater than 99%, or greater than 99.9% of intraluminal amylase activity. We conclude that commercial amylase inhibitors failed to decrease starch digestion in vivo mainly because they have insufficient antiamylase activity. However, a partially purified inhibitor with increased specific activity is stable in human gastrointestinal secretions, slows dietary starch digestion in vitro, rapidly inactivates amylase in the human intestinal lumen, and, at acceptable oral doses, may decrease intraluminal digestion of starch in humans. Such an inhibitor therefore deserves study.

Reliability of psychiatric diagnosis in hospitalized adolescents. Interrater agreement using DSM-III

To determine the reliability of psychiatric diagnosis in hospitalized adolescents, 95 consecutively admitted patients were diagnosed independently by two experienced clinicians using DSM-III criteria. Diagnostic judgments were based on joint interview of the patient via a structured mental-status examination, nursing observations, and referral materials. Concordance was analyzed by the kappa coefficient. A total of 13 DSM-III categories were used to classify this cohort, with the majority of categories representing traditional syndromes of functional psychopathology. There was complete agreement between the raters for more than three fourths of the patients. Levels of agreement for the categories of schizophrenia and major affective disorder were similar to values obtained in recent studies of adult patients. The results are discussed in relation to historical conceptions of adolescent psychopathology.

Stereochemistry of binding of the tetrapeptide acetyl-Pro-Ala-Pro-Tyr-NH2 to porcine pancreatic elastase. Combined use of two-dimensional transferred nuclear Overhauser enhancement measurements, restrained molecular dynamics, X-ray crystallography and molecular modelling

A nuclear magnetic resonance study of the conformation of the tetrapeptide acetyl-Pro-Ala-Pro-Tyr-NH2 bound to porcine pancreatic elastase is presented. From two-dimensional transferred nuclear Overhauser enhancement measurements, a set of 23 approximate distance restraints between pairs of bound ligand protons, indicative of an extended type structure, is derived. The structure of the bound tetrapeptide is then refined from two different starting structures (an extended beta-strand and a polyproline helix) by restrained molecular dynamics, in which the interproton distances are incorporated into the total energy of the system in the form of effective potentials. Convergence to essentially the same average restrained dynamics structures is achieved. The refined structures are then modelled into the active site of elastase by interactive molecular graphics. The determination of the anchor point of the bound tetrapeptide on the enzyme was aided by a simultaneous crystallographic study which, despite the fact that only electron density for a Pro-X dipeptide fragment was visible, enabled both the approximate position and orientation of binding to be determined. It is found that the tetrapeptide is bound in the S' binding site in the reverse orientation found in other serine protease-inhibitor complexes and is stabilized both by hydrogen-bonding and by van der Waals' interactions.

Induction of cytokines in cynomolgus monkeys by the immune response modifiers, imiquimod, S-27609 and S-28463

Imiquimod, S-27609 and S-28463 are imidazoquinolines known to have antiviral and antitumour properties mediated by the induction of cytokines, in particular interferon alpha (IFN-alpha). This study evaluated these compounds for their ability to induce cytokines and cytokine specific messenger RNAs (mRNA) in cynomologus monkeys (Macaca fascicularis). Peripheral blood mononuclear cell (PBMC) cultures from monkeys produced IFN, interleukin 1beta (IL-1beta), IL-6 and IL-8 after treatment with imiquimod, S-27609 and S-28463. Tumour necrosis factor alpha (TNF-alpha) was also increased in cultures stimulated with S-27609 or S-28463. Monkey PBMCs stimulated with imiquimod, S-27609 and S-28463 showed increased mRNA levels of IFN-alpha, IL-1alpha, IL-6 and the IFN inducible protein, MxA above those seen in untreated cultures. S-27609 and S-28463 also had higher TNF-alpha mRNA expression than cultures not receiving drugs. When compared to lipopolysaccharide (LPS), S-27609 was less effective at inducing IL-1beta, IL-6, IL-8 and TNF-alpha but induced higher concentrations of IFN. Similar results were seen when evaluating cytokine mRNA levels. Upon oral administration to monkeys, S-28463 stimulated a dose-dependent increase in serum concentrations of IFN, TNF-alpha, IL-1 receptor antagonist (IL-1Ra) and IL-6, while imiquimod induced increases in IFN and IL-1Ra concentrations. Finally, skin biopsies from monkeys treated topically with S-28463 had increases over baseline in mRNA for IFN-alpha, IL-1alpha, IL-6 and MxA protein. The data show that imidazoquinolines induce cytokines and cytokine specific mRNA in cynomolgus monkeys. These results demonstrate the usefulness of human amplimers and human ELISAs in the detection of cytokine specific mRNAs and proteins in cynomolgus monkeys.