Controlling the thermal stability of thin films by interfacial engineering.

The quantized electronic structure in Pb films on Si(111) varies substantially as the film thickness increases. The changes in electronic energy cause the thermal stability of the films to oscillate with an approximate bilayer period. The phase of the oscillations can be controlled by interfacial engineering. Comparison of Pb films prepared on Si(111) terminated by In, Au, and Pb as interfactants reveals a phase reversal. For , films made of odd numbers of atomic layers (5, 7, and 9) are more stable than the even ones. This trend is reversed for the other two cases.

Chemical tuning of metal-semiconductor interfaces.

We report a study of the Schottky barrier for Pb films grown on Si surfaces terminated by various metals (Ag, In, Au, and Pb) to explore the atomic-scale physics of the interface barrier and a means to control the barrier height. Electronic confinement by the Schottky barrier results in quantum well states in the Pb films, which are measured by angle-resolved photoemission. The barrier height is determined from the atomic-layer-resolved energy levels and the line widths. A calculation based on the known interface chemistry and the electronegativity yields predicted barrier heights in good agreement with the experiment.

Delta-9-tetrahydrocannabinol delays the gastric emptying of solid food in humans: a double-blind, randomized study.

BACKGROUND: Delta-9-tetrahydrocannabinol (THC), the active constituent of marijuana, is an effective agent in the prevention of chemotherapy-induced nausea and vomiting. AIM: To determine the effect of THC on gastric emptying of a radiolabelled solid food in humans. METHODS: Thirteen healthy volunteers underwent gastric emptying studies after receiving THC and placebo in a randomized double-blind fashion on 2 separate days. THC, at a dose of 10 mg/m2 of body surface area, or placebo were administered. RESULTS: Gastric emptying after THC was slower than placebo in all subjects. Mean percentage of isotope remaining in the stomach was significantly greater than after placebo from 30 min (85.5 +/- 4.3% vs. 94.2 +/- 1. 4% placebo and THC, respectively, P < 0.05) to 120 min (45.6 +/- 7. 2% vs. 73.9 +/- 7.1% placebo and THC, respectively, P < 0.001) after the test meal. No correlation was found between plasma THC levels and the delay in gastric emptying. CONCLUSIONS: THC at a dose used for preventing chemotherapy-induced nausea and vomiting significantly delays gastric emptying of solid food in humans. Therefore, the anti-emetic property of THC may be mediated through the central nervous system.

A diagnostic comparison of homeless and nonhomeless patients in an urban mental health clinic.

This study compared demographic and diagnostic characteristics of a sample of homeless outpatient mental health clinic attenders with a domiciled comparison group from the same clinic. Data on demographic variables and DSM-III-R psychiatric diagnoses were collected over a two-year period on a consecutive sample of 166 homeless and 117 nonhomeless clinic attenders. Data on demographics and psychiatric diagnoses of the homeless clinic attenders were further compared with data collected systematically from 900 homeless individuals in the same city. In the clinic, homeless subjects were more often members of ethnic minorities, and homeless women were significantly younger and better educated than their nonhomeless counterparts. Rates of schizophrenia, bipolar disorder, and somatization disorder were not significantly different between homeless and nonhomeless groups. Major depression was about four times as prevalent in nonhomeless men as in homeless men. Homeless men were significantly more likely than nonhomeless men to qualify for a diagnosis of alcohol use disorder, and homeless women were more likely than other women to qualify for a diagnosis of drug use disorder. Both homeless men and women were significantly more likely than their domiciled counterparts to meet criteria for antisocial personality disorder. Personality disorder other than antisocial was more prevalent in nonhomeless men than in homeless men. Combined rates of personality disorder were significantly higher among homeless than nonhomeless women, but not men. Homeless clinic attenders were demographically and diagnostically very similar to a general homeless population in the same city. The only diagnosis that was more prevalent in the homeless clinic than in the homeless community was antisocial personality disorder. We concluded that because of difference in diagnostic prevalence, homeless and nonhomeless individuals in mental health clinics need to be considered independently. Clinicians treating homeless outpatients may benefit from having special facility in diagnosis and management of antisocial personality disorder and substance abuse, along with expertise in other psychiatric disorders in this population.

A comparison of clinical and structured interview diagnoses in a homeless mental health clinic.

OBJECTIVE: This study compared psychiatric diagnoses ascertained by independent clinicians with structured research interviews of homeless psychiatric patients assessed in a mental health clinic and in the community. Problems of both overdiagnosis and underdiagnosis in structured research interviews compared to clinician assessment were predicted. METHOD: Over a period of a year, 97 patients referred to a mental health clinic for homeless people were assessed with the Diagnostic Interview Schedule (DIS) administered by a clinical social worker who then completed a full clinical psychiatric social work assessment. These same patients received a thorough and systematic clinical psychiatric evaluation by a psychiatrist or psychologist, both experienced with this population. These clinicians gathered data from multiple sources, often with extended observation over time. The DIS and clinician diagnoses were made blind to one another and then compared; the clinician was often made aware of some of the symptoms that the social worker had elicited, but not whether the elicited material was from the DIS or from the clinical assessment. Diagnoses of 33 clinic patients previously assessed by trained nonclinician DIS interviews in an epidemiologic study of the homeless population in the community were also compared to clinician diagnoses, and no information from these patients' survey DIS interviews was made available to the clinicians. RESULTS: Compared to clinician assessment, structured interviews underdiagnosed antisocial personality disorder (ASPD) and overdiagnosed major depression. Alcohol use disorder and schizophrenia showed only small discrepancies by assessment method. Drug use disorder revealed no bias according to method of ascertainment, but showed very discrepant kappa levels comparing DIS to clinician assessment in the two different comparison contexts. CONCLUSIONS: If structured research methods assessing the homeless population actually overestimate depression, underestimate ASPD, and misclassify drug abuse, then policies stemming from structured interview research recommendations may call for levels and types of services not optimally suited to the reality of this population's needs. Because mental illness and substance abuse are thought to be critical factors in the generation and perpetuation of homelessness, the issue of accurate diagnosis is tantamount to understanding and providing workable solutions to the problem of homelessness. Further research is needed to untangle potential confounders of the homeless situation to psychiatric diagnosis.

Effect of metoclopramide in diabetic gastroparesis.

The aims of our study were to: determine the effect of metoclopramide parenterally and orally on delayed gastric emptying of a radionuclide test meal in symptomatic patients with diabetic gastroparesis not explained by ulceration or other mechanical problems; and evaluate in a double-blind crossover fashion the efficacy of metoclopramide in relieving the symptoms of diabetic gastroparesis. Thirteen patients with subjective evidence of gastric stasis had delayed gastric emptying of an isotope-labeled semisolid meal which was significantly accelerated (p less than 0.05) after 10 mg of metoclopramide parenterally. Patients then received metoclopramide 10 mg and placebo before meals and prior to retiring for 3 weeks in a randomized double-blind crossover design. During metoclopramide therapy nausea, vomiting, anorexia, fullness, and bloating were significantly (p less than 0.05) ameliorated compared to placebo with an overall mean symptom reduction of 52.6%. Gastric emptying studies after completion of the trial is seven patients, subjectively improved and receiving open-labeled metoclopramide, showed significantly less gastric retention. Individual improvements in gastric emptying after parenteral or oral metoclopramide, however, could not be correlated with symptom change during the treatment trial. We conclude that metoclopramide is an important therapeutic adjunct in the management of diabetic gastroparesis and its therapeutic effects are mediated through its prokinetic properties as well as centrally mediated antiemetic actions.

A multicenter placebo-controlled clinical trial of oral metoclopramide in diabetic gastroparesis.

Metoclopramide tablets were compared with placebo in the treatment of gastrointestinal symptoms in 40 patients with diabetic gastroparesis. Results of a 3-wk double-blind study indicate that metoclopramide at a dosage of one 10-mg tablet four times daily reduced nausea, vomiting, fullness, and early satiety and improved meal tolerance better than placebo. Statistically significant differences were noted for nausea and postprandial fullness. Mean gastric emptying assessed by radionuclide scintigraphy was significantly improved in the metoclopramide-treated group when compared with their baseline result. Metoclopramide is an effective agent for improving the upper gastrointestinal motor function in diabetic patients with gastroparesis.