Mast cells

Mast cells are found resident in tissues throughout the body, particularly in association with structures such as blood vessels and nerves, and in proximity to surfaces that interface the external environment. Mast cells are bone marrow-derived and particularly depend upon stem cell factor for their survival. Mast cells express a variety of phenotypic features within tissues as determined by the local environment. Withdrawal of required growth factors results in mast cell apoptosis. Mast cells appear to be highly engineered cells with multiple critical biological functions. They may be activated by a number of stimuli that are both Fc epsilon RI dependent and Fc epsilon RI independent. Activation through various receptors leads to distinct signaling pathways. After activation, mast cells may immediately extrude granule-associated mediators and generate lipid-derived substances that induce immediate allergic inflammation. Mast cell activation may also be followed by the synthesis of chemokines and cytokines. Cytokine and chemokine secretion, which occurs hours later, may contribute to chronic inflammation. Biological functions of mast cells appear to include a role in innate immunity, involvement in host defense mechanisms against parasitic infestations, immunomodulation of the immune system, and tissue repair and angiogenesis.     

Bovine respiratory syncytial virus protects cotton rats against human respiratory syncytial virus infection

Human respiratory syncytial virus (HRSV) is the most frequent cause of severe respiratory infections in infancy. No vaccine against this virus has yet been protective, and antiviral drugs have been of limited utility. Using the cotton rat model of HRSV infection, we examined bovine respiratory syncytial virus (BRSV), a cause of acute respiratory disease in young cattle, as a possible vaccine candidate to protect children against HRSV infection. Cotton rats were primed intranasally with graded doses of BRSV/375 or HRSV/Long or were left unprimed. Three weeks later, they were challenged intranasally with either BRSV/375, HRSV/Long (subgroup A), or HRSV/18537 (subgroup B). At intervals postchallenge, animals were sacrificed for virus titration and histologic evaluation. Serum neutralizing antibody titers were determined at the time of viral challenge. BRSV/375 replicated to low titers in nasal tissues and lungs. Priming with 10(5) PFU of BRSV/375 effected a 500- to 1,000-fold reduction in peak nasal HRSV titer and a greater than 1,000-fold reduction in peak pulmonary HRSV titer upon challenge with HRSV/Long or HRSV/18537. In contrast to priming with HRSV, priming with BRSV did not induce substantial levels of neutralizing antibody against HRSV and was associated with a delayed onset of clearance of HRSV upon challenge. Priming with BRSV/375 caused mild nasal and pulmonary pathology and did not cause exacerbation of disease upon challenge with HRSV/Long. Our findings suggest that BRSV may be a potential vaccine against HRSV and a useful tool for studying the mechanisms of immunity to HRSV.     

A clinico-social study of peripheral vessel anomalies in children

The authors generalize results of examinations and operative treatment of 310 children with abnormalities of the venous and lymphatic vessels. References for differential diagnostics are described and term for operative interventions are given.     

Reducing the period of immobilization following pressure sore surgery: a prospective, randomized trial

The primary structures of two subunits of an alpha-amylase inhibitor (alpha AI-2) from a wild common bean (Phaseolus vulgaris) were revealed by a comparison of the amino acid sequence previously deduced from the nucleotide sequence with the amino- and carboxyl-terminal amino acid sequences determined by conventional methods. The polypeptide molecular weight of alpha AI-2 obtained by the light-scattering technique, considered together with the sequence molecular weights revealed for the subunits, indicated that alpha AI-2 has the subunit stoichiometry of an alpha 2 beta 2 complex. These structural features were closely similar to those recently elucidated for a white kidney bean (P. vulgaris) alpha-amylase inhibitor, which is quite different in the inhibitory specificity from alpha AI-2. The post-translational processing of the precursor glycoproteins to form the tetrameric structure appeared to require an Arg residue close to the processing site. Further, the proper associations of the subunits into the tetrameric structures seemed to be strictly controlled by a few amino acids on the subunit interfaces.     

Hierarchical cubic networks

We introduce a new interconnection network for large-scale distributed memory multiprocessors called the hierarchical cubic network (HCN). We establish that the number of routing steps needed by several data parallel applications running on a HCN-based system and a hypercube-based system are about identical. Further, hypercube connections can be emulated on the HCN in constant time. Simulation of uniform and localized traffic patterns reveal that the normalized average internode distances in a HCN are better than in a comparable hypercube. Additionally, the HCN also has about three-fourths the diameter of a comparable hypercube, although it uses about half as many links per node-a fact that has positive ramifications on the implementation of HCN-connected systems     

Use of subdermal contraceptive implants in a community-based family planning program. Experience after two years

In North Carolina, the Rutherford County Family Planning Council obtained funds from a special grant for levonorgestrel implants for women not eligible for medical assistance benefits. The Council approved the following approaches to promoting responsible sexual behavior and preventing unwanted pregnancy: creation of an interagency council to monitor the program, education in the schools on responsible sexual behavior, establishment of an information-sharing network for social service agencies, and expanded, low-cost or free family planning services. During 1992-1993, clinicians at the county health department and in private practices inserted implants in 287 women aged 13-37 living mainly in Rutherford County but also in McDowell and Polk counties. A survey was also conducted in the public high school to obtain self-assessment and information about family planning from female adolescents. Age distribution of the acceptors of the contraceptive implants was 40% for 13-19 year olds (the initiative's target group), 34% for 21-25 year olds, and 32% for 18-20 year olds (32%). The two-year insertion rate for women aged 10-19 was 17.3/1000 compared to 20.8/1000 for women aged 20-29. The implantation rate was greatest among 18-25 year olds and lowest among women aged 26 and older. The method of payment for implantation was medical assistance in 69% of cases and a philanthropic foundation for women not eligible for medical assistance in 29% of cases. 8% had the implants removed during the study period. The leading reason for removal was psychological distress (25%), followed by headaches (20.8%), desire to conceive (16.7%), bleeding (12.5%), and medical contraindication (12.5%). The interval between implantation and removal ranged from less than 3 months to more than 12 months. 2.3% of the female high school students used implants. Among the 596 students who were sexually active, 4.2% used implants, 1.85% used a diaphragm, 27.5% used condoms, and 15% used oral contraceptives. The implant acceptors attended 65% of scheduled 3-month follow-up visits.     

Field trial of a locally produced, killed, oral cholera vaccine in Vietnam

BACKGROUND: Several studies have shown that orally administered killed cholera vaccines are safe and protective in populations at risk of cholera in developing countries. However, these vaccines have not been adopted for use in developing countries because of their expense and limited efficacy in young children. We have tested an inexpensive, killed whole-cell cholera vaccine developed and produced in Vietnam. METHODS: The efficacy of the vaccine was assessed in a large-scale, open field trial in people at least 1 year old residing in 22,653 households in the central coastal city of Hue. Alternate households were assigned vaccine (67,395 people; two doses per person) or no vaccine (67,058 people). Surveillance for cholera was conducted in all Ministry of Health facilities serving this population. Analysis was by intention to treat. FINDINGS: During an outbreak of El Tor cholera 8-10 months after vaccination, 37 cases of cholera requiring inpatient care occurred among age-eligible people allocated to the vaccine group, and 92 cases among age-eligible people allocated to the no-vaccine group (protective impact 60% [95% CI 40-73]). Among the 51,975 people who received the complete two-dose vaccine regimen, the protective efficacy was 66% (46-79): in this subset, the protective efficacy was similar for children aged 1-5 years (68%) and for older people (66%). INTERPRETATION: These findings suggest that oral killed whole-cell vaccines can confer substantial protection against El Tor cholera in young children, who are at highest risk of cholera in endemic settings. An inexpensive, locally produced, and effective oral cholera vaccine may be within reach of the limited health-care budgets of poor countries with endemic cholera, if our findings can be replicated in a randomised double-blind trial.