The adsorption and desorption of ethanol ices from a model grain surface.

Reflection absorption infrared spectroscopy (RAIRS) and temperature programed desorption (TPD) have been used to probe the adsorption and desorption of ethanol on highly ordered pyrolytic graphite (HOPG) at 98 K. RAIR spectra for ethanol show that it forms physisorbed multilayers on the surface at 98 K. Annealing multilayer ethanol ices (exposures >50 L) beyond 120 K gives rise to a change in morphology before crystallization within the ice occurs. TPD shows that ethanol adsorbs and desorbs molecularly on the HOPG surface and shows four different species in desorption. At low coverage, desorption of monolayer ethanol is observed and is described by first-order kinetics. With increasing coverage, a second TPD peak is observed at a lower temperature, which is assigned to an ethanol bilayer. When the coverage is further increased, a second multilayer, less strongly bound to the underlying ethanol ice film, is observed. This peak dominates the TPD spectra with increasing coverage and is characterized by fractional-order kinetics and a desorption energy of 56.3+/-1.7 kJ mol(-1). At exposures exceeding 50 L, formation of crystalline ethanol is also observed as a high temperature shoulder on the TPD spectrum at 160 K.

Reflection absorption infrared spectroscopy and temperature programmed desorption investigations of the interaction of methanol with a graphite surface.

Reflection absorption infrared spectroscopy (RAIRS) and temperature programmed desorption (TPD) have been used to investigate the adsorption of methanol (CH(3)OH) on the highly oriented pyrolytic graphite (HOPG) surface. RAIRS shows that CH(3)OH is physisorbed at all exposures and that crystalline CH(3)OH can be formed, provided that the surface temperature and coverage are high enough. It is not possible to distinguish CH(3)OH that is closely associated with the HOPG surface from CH(3)OH adsorbed in multilayers using RAIRS. In contrast, TPD data show three peaks for the desorption of CH(3)OH. Initial adsorption leads to the observation of a peak assigned to the desorption of a monolayer. Subsequent adsorption leads to the formation of multilayers on the surface and two TPD peaks are observed which can be assigned to the desorption of multilayer CH(3)OH. The first of these shows a fractional order desorption, assigned to the presence of hydrogen bonding in the overlayer. The higher temperature multilayer desorption peak is only observed following very high exposures of CH(3)OH to the surface and can be assigned to the desorption of crystalline CH(3)OH.

Pulmonary manifestations of HIV infection in the era of highly active antiretroviral therapy.

STUDY OBJECTIVES: To determine whether the spectrum of HIV-related pulmonary disease seen by a university medical center Pulmonary and Critical Care Medicine Service has changed since the introduction of highly active antiretroviral therapy (HAART). DESIGN: Retrospective chart review. SETTING: A tertiary care university hospital. PATIENTS: All HIV-infected patients referred to the Pulmonary and Critical Care Medicine Service from January 1, 1993, through December 31, 1995 (era 1) and from July 1, 1997, through June 30, 2000 (era 2). INTERVENTIONS: Inpatient and outpatient charts were reviewed for data regarding patient demographics, CD4 cell counts, viral load levels, duration of HIV seropositivity, history of opportunistic infections, and final diagnosis. RESULTS: Pneumocystis carinii pneumonia (PCP) was less common in the HAART era than in the pre-HAART era, whereas bacterial pneumonia and non-Hodgkin's lymphoma (NHL) were more common in the HAART era than in the pre-HAART era. HAART was protective against PCP (odds ratio [OR], 0.37; confidence interval [CI], 0.16 to 0.89) in a manner dependent on the CD4 cell count. Patients receiving HAART were at increased risk for the development of bacterial pneumonia (OR, 2.41; CI, 1.12 to 5.17) and NHL (OR, 15.11; CI, 3.14 to 28.32). A history of PCP indicated a risk factor for bacterial pneumonia (OR, 2.14; CI, 1.13 to 4.04). A history of cytomegalovirus infection indicated a risk factor for NHL (OR, 6.0; CI, 1.27 to 28.32). CONCLUSIONS: There have been significant changes in the spectrum of HIV-related pulmonary complications seen by our Pulmonary and Critical Care Medicine Service in the HAART era.

Risk factors for hypercarbia, subcutaneous emphysema, pneumothorax, and pneumomediastinum during laparoscopy.

OBJECTIVE: To determine independent predictors for the development of hypercarbia, subcutaneous emphysema, pneumothorax, and pneumomediastinum during laparoscopy. METHODS: We reviewed 968 laparoscopic cases between January 1, 1997, and December 31, 1998. Patients who had hypercarbia (end-tidal carbon dioxide of 50 mmHg or greater), pneumothorax/pneumomediastinum, and subcutaneous emphysema were compared with controls according to age, operative time, type of surgery, extraperitoneal or intraperitoneal approach, preexisting medical conditions, body mass index, sex, use of Hasson technique, and number of surgical ports. Maximum positive end-tidal CO(2) (PETCO(2)) was added as an independent variable for subcutaneous emphysema, pneumothorax, and pneumomediastinum. Data were analyzed using univariate analysis and then subjected to multivariate analysis using multiple logistic regression analysis. RESULTS: Incidence rates were 5.5% for hypercarbia, 2.3% for subcutaneous emphysema, and 1.9% for pneumothorax/ pneumomediastinum. Independent risk factors for development of hypercarbia were operative time greater than 200 minutes (odds ratio [OR] 2.02), patient age greater than 65 years (OR 2.19), and Nissen fundoplication surgery (OR 3.18). Predictors of the development of subcutaneous emphysema were PETCO(2) greater than 50 mmHg (OR 3.49), operative time greater than 200 minutes (OR 5.27), and the use of six or more surgical ports (OR 3.06). Variables that predicted the development of pneumothorax and/or pneumomediastinum were PETCO(2) greater than 50 mmHg (OR 4. 15) and operative time greater than 200 minutes (OR 20.49). CONCLUSION: Longer operative times, higher maximum measured end-tidal CO(2), greater number of surgical ports, older patient age, and Nissen fundoplication surgery predispose patients to hypercarbia-related complications during laparoscopy.

The ability of recombinant tissue plasminogen activator to inhibit post-radical pelvic surgery adhesions in the dog model.

We investigated the ability of recombinant tissue plasminogen activator to inhibit post-radical pelvic surgery adhesions formation in 40 adult female canines undergoing radical hysterectomy, bilateral salpingo-oophorectomy, omentectomy, resection of pelvic and abdominal peritoneum, and placement of a peritoneal access catheter. Immediately after operation one half of animals received either recombinant tissue plasminogen activator, 1 mg/kg weight, diluted in 9 ml sterile normal saline solution per milligram of the plasminogen activator or 10 ml vehicle per kilogram intraperitoneally every 12 hours for a total of 10 doses. A single control animal died postoperatively of complications of intestinal obstruction. No bleeding abnormalities were noted in either group of animals. Four weeks after surgery, animals underwent reexploration and adhesions were quantified. Adhesion scores for the animals treated with recombinant tissue plasminogen activator (n = 20; mean score, 1.29 +/- 1.97; median, 0.6) were significantly less than for control animals (n = 19; mean score, 4.64 +/- 3.71; median, 3.86; p = 0.03). Whereas recombinant tissue plasminogen activator appears to effectively prevent post-radical pelvic surgery adhesions in this canine model, phase I and II trials in humans will be required to determine safety and clinical benefit.

Gonadal protection and fecundity rates in cyclophosphamide-treated rats.

Premature ovarian failure and reduced fecundity are well-documented consequences of cytotoxic chemotherapy used to treat patients with malignant diseases. To investigate the ability of different hormonal agents to block the effects of cyclophosphamide (CTX) on reproductive function, sexually mature female Long-Evans rats were studied. Model development demonstrated that CTX, 6 mg/kg/day, 5 days/week for 3 weeks, was successful at inducing acyclicity and significantly reducing fertility and fecundity, with acceptable mortality, when compared to higher/lower dosages. Utilizing this model, animals were treated with CTX in combination with an inert vehicle, Lupron, 80 micrograms/kg every 24 h, Lupron, 40 micrograms/kg every 12 h, or s.c. progesterone capsules obtaining serum progesterone levels of 20-30 ng/ml. We concluded that progesterone was able to protect the gonad from the negative effects of CTX, maintaining fertility and fecundity rates not significantly different from those of untreated control animals. Lupron given every 12 h had a similar effect on fertility, but failed to protect fecundity (P less than 0.001).

Surgical antibiotic prophylaxis, patient morbidity, and cost reduction: a three-year study.

Twenty-five to 50 percent of all antibiotics prescribed for hospitalized patients are for prevention, not treatment, of infection. Procedures to institute rational, cost-effective utilization of these agents should have a significant impact on drug cost and pharmacy inventory. Several authors have described antibiotic cost reduction programs using pharmacy intervention. Unfortunately, measures that are successful in one institution may not be effective or appropriate in another. A three-year study was undertaken to examine the impact on physician prescribing of an infection control bulletin and formalized recommendation for antibiotic utilization. Patient records also were examined to determine if any change in antibiotic utilization would influence patient morbidity. Over the three examination periods there was a significant reduction in cost of prophylaxis in 7 surgical groups, and a trend toward cost reduction in 21 additional groups. Cost of prophylaxis also increased in other surgical groups. Cost reduction was associated with limited duration of prophylaxis and a shift toward use of first generation cephalosporin products. Patient morbidity did not differ significantly.