Approach to the patient with pulmonary disease

The approach to the HIV-infected patient with pulmonary disease is summarized by the algorithms in Figures 3 and 4. These are not intended to be followed in a rigid step-wise fashion. Rather, the practitioner's knowledge of the patient with his or her accompanying medical risks influences the path taken, including the depth and the speed of the evaluation. For example, the patient with cough who is afebrile and breathing at 18 breaths a minute, with a normal chest radiograph and a CD4 count of 350 cells/mm3, is reasonably treated with a macrolide or cephalosporin for bacterial bronchitis and clinical follow-up while awaiting cultures (see Fig. 4). A febrile patient with a cough productive of thin mucus, but known to have a CD4 count of 60 cells/mm3 should be started on anti-PCP therapy while being evaluated for PCP with an induced sputum and if nondiagnostic, a bronchoscope despite a normal chest radiograph. Screening can be as simple as placing an oximeter on the patient's finger in the clinic. If the oxygen saturation of a patient with a normal chest radiograph is low, then the patient should be hospitalized and begun on treatment for PCP while diagnostic evaluation is initiated. If the oxygen saturation is normal, the patient can be exercised to elicit desaturation. If there is no desaturation, PCP is unlikely. If the results are equivocal (i.e., a decrease in saturation, but less than 3%), rest and exercise arterial blood gases can be performed, along with a Dlco-Gallium scanning can be done in patients known to have abnormal Dlco or those who cannot exercise. Patients with focal infiltrates who have acute onset of symptoms (see Fig. 4) commonly have bacterial infections, but the possibility of PCP or TB should not be dismissed. Induced sputum should be examined if TB or PCP is suspected. Patients who are severely ill might go quickly to bronchoscopy without awaiting improvement on empiric therapy. The patient with diffuse infiltrates (see Fig. 4) needs no screening because the presence of disease is apparent from the radiograph. The diagnostic part quickly leads to bronchoscopy for these patients and the initiation of therapy for PCP when suspected. In patients with known pulmonary KS, gallium scanning can be helpful to rule out acute infection, but bronchoscopy is warranted if the patient is severely ill, or at high risk for PCP. This approach should avoid unnecessary procedures in patients with simple bacterial infections, without missing opportunistic infections and tumors.     

Comparative Analysis of Chlorine Dioxide, Free Chlorine and Chloramines on Bacterial Water Quality in Model Distribution Systems

Drinking water utilities may be required to change disinfectant to improve water quality and meet more stringent disinfection regulations. This research was conducted to assess and compares chlorine dioxide to free chlorine and chloramines on bacterial water quality monitored within model distribution systems (i.e., annular reactors). Following colonization with nondisinfected water, annular reactors containing either polycarbonate or cast iron coupons were treated with free chlorine, chlorine dioxide or chloramines. Two disinfectant doses (low/high) were tested for each disinfectant. Under specific environmental conditions, bacterial inactivation varied as a function of the disinfectant type and dose, sample type (bulk water versus biofilm bacteria) and coupon material. The ranking by efficiency was as follows: chlorine dioxide > chlorine > chloramines. On preformed biofilms of 106–107?cfu/cm2, the continuous application of a disinfectant led to a log removal of heterotrophic bacteria concentrations for suspended and biofilm bacteria ranging from 1.1 to 4.0, and from 0.2 to 2.5, respectively. Doubling the amount of disinfectant doses led to an additional log inactivation of 1–2.5 of heterotrophic bacteria levels. This study demonstrates that bacterial inactivation in distribution systems is governed by various inter-related parameters. The data indicate that chlorine dioxide represents a viable alternative for secondary disinfection in distribution systems.     

Identification and characterization of the PutP proline permease that contributes to in vivo survival of Staphylococcus aureus in animal models

Staphylococcus aureus is an important pathogen of humans and other animals, causing bacteremia, abscesses, endocarditis, and other infectious syndromes. A signature-tagged mutagenesis (STM) system was adapted for use in studying the genes required for in vivo survival of S. aureus. An STM library was ultimately created in S. aureus RN6390, with Tn917 being used to create the transposon mutations. Pools of S. aureus RN6390 mutants were screened in mouse abscess, bacteremia, and wound infection models for growth attenuation after in vivo passage. One of the mutants that was identified displayed marked attenuation following large-pool screening in all three animal models, which was confirmed in bacteremia and endocarditis models of infection with a smaller pool of mutants. Sequence analysis of the entire open reading frame showed a 99% identity to the high-affinity proline permease (putP) gene characterized in another strain of S. aureus. In wound and murine abscess infection models, the putP mutant was approximately 10-fold more attenuated than was wild-type strain RN6390. Another S. aureus strain transduced with the putP mutation also displayed an attenuated phenotype after passage in the wound model. A [3H]proline uptake assay showed that less proline was specifically transported into the putP mutant than into strain RN6390. The reduced viability of the bacteria possessing the mutation in the S. aureus high-affinity proline permease suggests that proline scavenging by the bacteria is important for in vivo growth and proliferation and that analogs of proline may serve as potential antistaphylococcal therapeutic agents.     

Sodium oxacillin in the horse: serum, synovial fluid, peritoneal fluid, and urine concentrations after single-dose intramuscular administration

Six healthy adult mares were given a single dose (25 mg/kg of body weight) of sodium oxacillin IM. Oxacillin concentrations in serum, synovial fluid, peritoneal fluid, and urine were measured serially over a 48-hour period. The mean peak serum oxacillin concentration was 9.75 microgram/ml at 0.5 hour after injection. Mean peak oxacillin concentrations in synovial and peritoneal fluids were 1.45 microgram/ml and 2.60 microgram/ml at 1 hour and 2 hours, respectively. These concentrations decreased in parallel with serum values and were not measurable at 48 hours. Urine concentrations of oxacillin were high, with a mean peak concentration of 2,790.2 microgram/ml at 0.5 hour.     

Strong, low density, hexylene- and phenylene-bridged polysilsesquioxane aerogel–polycyanoacrylate composites

Nanocomposite aerogels were prepared by chemical vapor deposition and polymerization of cyanoacrylate on the surface of bridged polysilsesquioxane aerogels. Phenylene- and hexylene-bridged aerogels were prepared by sol–gel polymerizations and supercritical carbon dioxide drying. Hydrophobic organic bridging groups in the polysilsesquioxane aerogels reduced the amount of adsorbed water available for initiating polymerizations and led to higher molecular weight polycyanoacrylate than was observed with silica aerogels. Densities increased as much as 65% due to the addition of the organic polymer, but the nanocomposite aerogels remained highly porous with surface areas between 440 and 750 m²/g. Polycyanoacrylate–phenylene-bridged aerogel composites were the strongest with flexural strengths up to 780 kPa or 16-fold stronger than the untreated phenylene-bridged aerogels and fivefold stronger than a silica aerogel of the same density. The strongest polycyanoacrylate–hexylene-bridged aerogel composites had flexural strength of 285 kPa or ninefold stronger than the untreated hexylene-bridged aerogels and twice as strong as a silica aerogel of comparable density. The greater strength of the new composites is, in part, due to the greater strength of the bridged aerogels. However, higher molecular weight polycyanoacrylate, due to less surface water on the hydrophobic bridged aerogels, also contributes to the greater nanocomposite strengths.     

The effect of hole diameter on the torsional mechanical properties of the equine third metacarpal bone

The torsional monotonic structural material properties of equine metacarpi with or without, either a 5/16 inch or 3/8 inch diameter bicortical lateromedial middiaphyseal hole were assessed to determine the effect of a hole on metacarpal strength. Torsional stiffness was not significantly effected by the presence of a bicortical hole, whereas yield and failure angles, torques and energies of metacarpi with a hole were 51% to 97% of those of intact bones. Significant differences were not apparent for yield and failure mechanical properties between metacarpi with a 5/16 inch diameter hole and metacarpi with a 3/8 inch diameter hole; however, postyield mechanical properties were lower for metacarpi with a 3/8 inch hole. Whereas some metacarpi with a 5/16 inch hole were capable of plastic deformation before failure, metacarpi with a 3/8 inch diameter hole appeared to have sufficient stress concentration to propagate complete fracture on structural yield.     

Varicella-zoster virus: infection, control, and prevention

Varicella-zoster virus is a herpes virus that produces a primary infection, chickenpox, manifested by a vesicular eruption and is considered one of the common childhood infectious diseases. After the initial infection the virus becomes latent, then when activated it is manifested as herpes zoster, commonly known as shingles. This highly communicable human disease is associated with serious morbidity and significant mortality, particularly among the immunocompromised. When introduced in the hospital, significant disruptions occur and serious sequelae may results. Recently, a live virus varicella vaccine was approved by the Food and Drug Administration in the United States. Studies have shown the vaccine to be safe and effective. Widespread use of this vaccine may be beneficial in reducing the opportunities for varicella-zoster virus introductions in health care settings.     

Maximum acceptable forces for repetitive wrist extension with a pinch grip

This study represents a continuation of a series of psychophysical studies on repetitive motions of the wrist conducted at the Liberty Mutual Research Center for Safety and Health. The purpose of the study was to quantify maximum acceptable forces for extension motions of the wrist performed with a pinch grip. Subjects grasped a handle with a pinch grip and moved it through a 1.57 rad (90°) extension wrist motion (similar to a light assembly operation). A psychophysical methodology was used in which the subject adjusted the resistance on the handle, and the experimenter manipulated or controlled all other variables. Twenty subjects performed the task at repetition rates of 15, 20 and 25 motions per minute. Subjects performed for 7 h per day, 5 days per week, for 4 weeks. The subjects were instructed to work as if they were on an incentive basis, getting paid for the amount of work they performed. Symptoms were recorded by the subjects during the last 5 min of each hour. The results are presented and compared with maximum acceptable forces for other types of wrist motion investigated in previous studies. Maximum acceptable force for wrist extension with a pinch grip is smaller than any of the other motions investigated so far.

Relevance to industry

Cumulative trauma disorders of the upper extremities continue to be a problem for industrial workers who perform repetitive tasks. Although a number of physical risk factors have been identified, there are very few data available for establishing acceptable levels of these risk factors. This study attempted to collect such data.     

Novel photoresist design based on electrophilic aromatic substitution

A new approach to resist materials that exhibit chemical amplification is based on systems comprised of three structural units at least one of which is polymeric: (a) an aromatic moiety such as poly(4-hydroxystyrene), Novolac, or other aromatic compounds which are susceptible to electrophilic aromatic substitution; (b) a latent electrophile which may be polyfunctional and, in the case of this study, is a carbocation precursor; (c) a material which generates strong acid upon irradiation. Exposure of a film containing these three structural components affords a latent image of acid dispersed in the polymer matrix. In a subsequent baking step, the photogenerated acid reacts with the latent electrophile releasing a very reactive carbocationic species which becomes bound to the aromatic moiety. As one of the components of the resist is polymeric and multifunctional, the result is a rapid increase in molecular weight due to branching and crosslinking of the chains. In terms of imaging, this process translates into the formation of a negative image of the mask although under some conditions a positive image may also be produced. The system shows a very high sensitivity and can provide high resolution images devoid of distortion due to the absence of swelling during development.