The anti-CD2 monoclonal antibody BTI-322 generates unresponsiveness by activation-associated T cell depletion.

The antihuman CD2 MoAb BTI-322 (Lo-CD2a) effectively inhibits T cell responses in vitro to allogeneic cells, which is followed by unresponsiveness to the original stimulator in secondary stimulation. We studied the xenogeneic human antiporcine mixed lymphocyte reaction (MLR), and utilized anti-T cell receptor (TCR) Vbeta family antibody-induced cell proliferation to determine the specificity and mechanism. BTI-322 and its humanized version, MEDI-507, effectively inhibited the primary xenogeneic MLR. After suboptimal primary stimulation using lower numbers of xenogeneic stimulator cells, the unresponsiveness in secondary culture was apparent only for xenogeneic stimulator cells of the original SLA haplotype, and not for third-party stimulators or allogeneic cells. The inhibition of primary MLR was not observed for nylon-wool-purified T cells, but was seen after reconstitution of purified T cells with monocytes. Similarly, anti-Vbeta family-specific stimulation showed family-specific unresponsiveness in secondary culture. This required the presence of the whole BTI-322 molecule: a F(ab')2 fragment was not effective. T cells of a distinct Vbeta family were depleted after stimulation with an anti-Vbeta family-specific antibody and BTI-322. We conclude that the inhibition by BTI-322 of a primary xenogeneic MLR or the response to an anti-TCR Vbeta antibody is associated with unresponsiveness upon restimulation, due to activation-associated cell depletion. In this process, the interaction between monocytes and the Fc part of the antibody is involved. This unique characteristic of BTI-322 suggests the potential of the antibody for tolerance induction in vivo, besides the potential use as a T cell depleting agent.

Clonal lines of transgenic fibroblast cells derived from the same fetus result in different development when used for nuclear transfer in pigs.

Different factors are believed to influence the outcome of nuclear transfer (NT) experiments. Besides the cell cycle stage of both recipient cytoplast and donor karyoplast, the origin of the donor cells (embryonic, fetal, and adult) is of interest. We compared in vitro development of NT embryos derived from small serum-starved (G0) or small cycling (G1) porcine fetal fibroblast cells. Serum starvation did not have a positive effect on cleavage rate or the percentage of embryos that developed to the morula and blastocyst stages. Next, we investigated the development of porcine NT embryos derived from different transgenic clonal cell lines that had originated from the same fetus. When different clonal lines of fetal fibroblasts were fused to enucleated metaphase II oocytes, differences in fusion rates as well as in development to the morula and blastocyst stages were observed (P < 0.05). When oocytes derived from sow ovaries were used as recipient cytoplasts, significantly better cleavage (P = 0.03) and blastocyst formation (P < 0.014) was obtained when compared with oocytes derived from gilts. Our data indicate that not only different cell lines, but also different clones derived from one primary cell line, result in different development when used for NT. In addition, the use of sow oocytes as a cytoplast source also improves the efficiency of NT experiments.

Nosocomial tuberculosis prevention measures among two groups of US hospitals, 1992 to 1996.

OBJECTIVE: To compare trends in nosocomial tuberculosis (TB) prevention measures and health-care worker (HCW) tuberculin skin test (TST) conversion of hospitals with HIV-related Pneumocystis carinii pneumonia (PCP) patients and other US hospitals from 1992 through 1996. DESIGN AND SETTING: Surveys in 1992 and 1996 of 38 hospitals with PCP patients in four high-HIV-incidence cities and 136 other US hospitals from the American Hospital Association membership list. PARTICIPANTS: Twenty-seven hospitals with PCP patients and 103 other US hospitals. RESULTS: In 1992, 63% of PCP hospitals and other US hospitals had rooms meeting Centers for Disease Control and Prevention (CDC) criteria (ie, negative air pressure, six or more air exchanges per hour, and air directly vented to the outside) for acid-fast bacilli isolation; in 1996, almost 100% had such isolation rooms. Similarly, in 1992, nonfitted surgical masks were used by HCWs at 60% of PCP hospitals and 68% at other US hospitals, while N95 respirators were used at 90% of PCP hospitals and 83% of other US hospitals in 1996. There was a significant decreasing trend in TST conversion rates among HCWs at both PCP and other US hospitals; however, this trend varied among all hospitals. HCWs at PCP hospitals had a higher risk of TST conversion than those at other US hospitals (relative risk, 1.71; p < 0.0001). CONCLUSION: From 1992 through 1996, PCP and other US hospitals have made similar improvements in their nosocomial TB prevention measures and decreased their HCW TST conversion rate. These data show that most hospitals are compliant with CDC TB guidelines even before the enactment of an Occupational Safety and Health Administration TB standard.

APIC and CDC survey of Mycobacterium tuberculosis isolation and control practices in hospitals caring for children. Part 1: Patient and family isolation policies and procedures. Association for Professionals in Infection and Epidemiology, Inc.

BACKGROUND: The 1994 Centers for Disease Control and Prevention draft Guidelines for Preventing the Transmission of Mycobacterium tuberculosis in Health-Care Facilities did not exempt pediatric facilities from instituting controls to prevent nosocomial tuberculosis (TB) transmission. Many researchers contend that TB disease in children does not require such rigid controls. We surveyed acute-care pediatric facilities in the United States to determine adherence to patient and family isolation policies and procedures. METHODS: The study included 4 mailings of a survey to infection control professionals at 284 US children's hospitals and adult acute-care hospitals with > 30 pediatric beds. RESULTS: The overall response rate was 69%. Only 41% of respondents reported having a written TB policy specifically designed for pediatric patients. Whereas 98% of respondents isolated pediatric patients with confirmed pulmonary TB, only 69% reported isolation of patients with miliary TB, and 79% reported isolation of patients with positive gastric aspirates. TB isolation policies for adult visitors were in place at 69% of hospitals, and 50% of hospitals evaluated adults for TB as part of the child's TB treatment plan. A median of 3 contact investigations occurred at each of 47% of respondent hospitals in the preceding 5 years. CONCLUSIONS: Isolation and infection control policies for children with pulmonary TB largely conformed to published guidelines but varied for children with nonpulmonary TB. Because the greatest risk of nosocomial TB transmission in pediatric facilities comes from adults with TB, a rapid TB screening process for parents and adult contacts accompanying affected children should be instituted at facilities caring for children.

APIC and CDC survey of Mycobacterium tuberculosis isolation and control practices in hospitals caring for children. Part 2: Environmental and administrative controls. Association for Professionals in Infection control and Epidemiology, Inc.

BACKGROUND: The 1994 Centers for Disease Control and Prevention draft Guidelines for Preventing the Transmission of Mycobacterium tuberculosis in Health-Care Facilities did not exempt pediatric facilities from instituting controls to prevent nosocomial tuberculosis (TB) transmission. Many researchers contend that TB disease in children does not require such rigid controls. We surveyed acute-care pediatric facilities in the United States to determine adherence to environmental and administrative control recommendations. METHODS: The study included 4 mailings of a survey to infection control professionals at 284 US children's hospitals and adult acute-care hospitals with > 30 pediatric beds. RESULTS: Isolation rooms (IRs) generally conformed to recommended guidelines; 92% of respondents reported IRs with > or = 6 air changes per hour, 90% reported 1-pass air and negative pressure, and 89% reported that IRs were private rooms. A sufficient number of inpatient IRs were reported by 88%, but only 42% had IRs in outpatient areas, and 19% had IRs in off-site clinics. Employee tuberculin skin-test programs were in place at 98% of facilities, but policies pertaining to implementation varied. Employees' use of personal respirators increased at respondent hospitals from 1991 to 1994, but as late as 1994, nearly one third still used surgical masks for high-risk procedures. CONCLUSIONS: Environmental and administrative controls used by respondent hospitals largely conformed to published guidelines. Because definitive studies that quantify the risk of nosocomial M tuberculosis transmission in pediatric settings have yet to be performed, pediatric facilities are required to have the same protections in place as do their adult counterparts.

Are US hospitals making progress in implementing guidelines for prevention of Mycobacterium tuberculosis transmission?

BACKGROUND: Outbreaks of tuberculosis (TB) in hospitals have occurred when the Centers for Disease Control and Prevention (CDC) guideline recommendations for preventing the transmission of Mycobacterium tuberculosis were not fully implemented. OBJECTIVE: To determine whether US hospitals are making progress in implementing the CDC guidelines for preventing TB. METHODS: In 1992, we surveyed all public (city, county, Veterans Affairs, and primary medical school-affiliated) US hospitals (n = 632) and 444 (20%) random samples of all private hospitals with 100 beds or more. In 1996, we resurveyed 136 random samples (50%) of all 1992 respondent hospitals with 6 or more TB admissions in 1991. RESULTS: Of the 1076 hospitals surveyed in 1992, 763 (71%) respondents returned a completed questionnaire. Among these, 536 (71%) of 755 reported having rooms that met CDC criteria for acid-fast bacilli isolation, ie, negative air pressure, 6 or more air exchanges per hour, and air directly vented to the outside. The predominant respiratory protective device for health care workers was nonfitted surgical mask and attending physicians were infrequently (50%) included in tuberculin skin-testing programs. In the 1996 resurvey, 103 (76%) of 136 respondents returned a completed questionnaire. Of these, 99 (96%) reported having rooms that met CDC criteria for acid-fast bacilli isolation. The N95 respiratory protective devices were predominantly used by health care workers, and attending physicians were increasingly (69%) included in the hospitals' tuberculin skin-testing programs. CONCLUSIONS: Most US hospitals are making progress in the implementation of CDC guidelines for preventing the transmission of M tuberculosis.

Regulation of nitric oxide synthesis by oxygen in vascular endothelial cells.

Vascular endothelial cells synthesize nitric oxide (NO) in response to agonists that elevate cytosolic free Ca2+ concentrations. Once activated, NO synthase (NOS) requires arginine, NADPH, and O2 as cosubstrates. In this study, we investigated the role of O2 in regulating endothelial NOS activity in intact bovine aortic endothelial cells by measuring the rate of nitrite (NO2-) and nitrate (NO3-) production after conversion of NO2- to S-nitrosoglutathione before analysis or after reduction of NO2- and NO3- to NO using acidic vanadium chloride. The basal rate of NO2- production was 6.5 +/- 0.8 pmol.min-1.mg protein-1. Thapsigargin (TG, 1 microM) elevated free cytosolic Ca2+ concentration and increased the rate of NO2- synthesis. At maximal concentrations of TG, the rate of stimulated NO2- production was linear for at least 20 min and was eightfold higher than the basal rate (53.5 +/- 1.8 pmol.min-1.mg protein-1). Incubation of cells in gas mixtures chosen to produce PO2 values in the physiological range led to a progressive fall in the rate of TG-stimulated NO2- production, as O2 concentrations were reduced from that of room air. The half-maximal effective concentration for NO2- production by intact cells was found to occur at 38 Torr. PO2 values higher than that of room air did not lead to a change in the rate of TG-stimulated NO2- production. To confirm that measurement of NO2- accurately reflects total NO production, both NO2- plus NO3- were measured in buffer samples from cells incubated in either room air or N2. The sum of these NO oxidation products was inhibited similarly by hypoxia. These findings suggest that O2 is an important determinant of NOS activity in hypoxic tissues or in vascular beds such as the pulmonary arterial or fetal circulation where PO2 values in the range of 40 Torr are encountered normally.

Detecting pediatric nosocomial infections: how do infection control and quality assurance personnel compare?

OBJECTIVE: To compare how well infection control (IC) and quality assurance (QA) personnel in a specialty setting identify the presence, type (nosocomial or community-acquired), and (if nosocomial) site of infection. METHODS: In 1994, we mailed a survey that included 21 pediatric case histories to IC and QA personnel in pediatric settings in the United States (children's hospitals and medical school-affiliated hospitals with pediatric wards of > 30 beds). From the case histories presented, the respondents were asked to determine whether an infection was present and, if so, whether it was nosocomial or community-acquired. If the infection was nosocomial, the respondent was asked to determine the site of the infection (e.g., urinary tract, bloodstream). RESULTS: From the 289 hospitals to which surveys were mailed, 131 respondents (45.3%) completed 212 surveys. Of the 212 returned surveys, 120 (56.6%) were completed by IC personnel and 92 (43.4%) were completed by QA personnel. Among the 183 respondents from acute care pediatric settings, 92.3% of IC personnel (96/104) and 54.4% of QA personnel (43/79) correctly identified at least 75% of the nosocomial infections (n = 14; p < 0.0001). IC and QA personnel were similar in ability to identify community-acquired infection (88/104 vs 70/79, respectively; p = 0.436). IC personnel were significantly more likely than QA personnel to accurately identify the following sites of infection: respiratory tract infection without secondary bloodstream infection, necrotizing enterocolitis, urinary tract infection with and without secondary bloodstream infection, primary bloodstream infection, surgical site infection, gastroenteritis, esophagitis, and clinical sepsis. CONCLUSIONS: Overall, IC personnel were more accurate than QA personnel in determining whether a nosocomial infection was present and in correctly determining most sites of infection. Both IC and QA personnel had difficulty identifying venous infection and respiratory tract infection with secondary bloodstream infection. Both IC and QA personnel could thus benefit from more concise definitions or further training in detection of these sites of nosocomial infections. In addition, QA personnel did not perform overall as well as IC personnel in identifying nosocomial infections and their sites; this finding suggests the need for QA personnel to be provided specific training on detection of nosocomial infections and validation of their ability to do so. Nosocomial infection surveillance should be the responsibility of those trained and proved capable of detecting these infections.

Status of tuberculosis infection control programs at Texas hospitals, 1989 through 1991.

BACKGROUND: Paralleling the resurgence of tuberculosis (TB) in the United States, the reported number of persons with TB in Texas increased by 33% during 1985 through 1992, the third largest rise among all the states. This increase prompted us to survey hospitals in Texas to determine their degree of compliance with recommendations in the Centers for Disease Control and Prevention TB guidelines. METHODS: In April 1992, we mailed a voluntary questionnaire about TB infection control practices, health care worker tuberculin skin testing procedures, and Mycobacterium tuberculosis laboratory methods to a convenience sample of hospitals in Texas. RESULTS: Of 180 hospitals surveyed, 151 (83%) returned completed questionnaires. Of these, 90 (60%) were nonteaching community hospitals; 28 (19%) were teaching community hospitals; 13 (9%) were university-affiliated hospitals; and 20 (13%) were other hospitals. The number of hospitals to which patients with TB were admitted increased from 98 (65%) in 1989 to 122 (81%) in 1991. Respondent hospitals had a mean of 183 acute care beds (median 100, range 5 to 999), 6 acid-fast bacillus isolation rooms (median 2, range 0 to 57) and 7.5 admissions/year of patients with TB (median 2, range 0 to 202). Of hospitals responding to specific questions, 20% (27/137) admitted patients with multidrug-resistant TB, 18% (25/140) reported not having any acid-fast bacillus isolation rooms, and 28% (35/125) had no rooms meeting all of the Centers for Disease Control and Prevention criteria for acid-fast bacillus isolation (negative air pressure, > or = 6 air changes per hour, and air directly vented to the outside). The tuberculin skin test conversions among health care workers rose from 246 (0.6%) in 1989 to 547 (0.9%) in 1991. CONCLUSION: Although the number of Texas hospitals admitting patients with TB increased during 1989 through 1991, many facilities still did not have infection control practices consistent with the 1992 Centers for Disease Control and Prevention TB guidelines.