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Biomedical subjects

M R Wallace

Publications and source records attributed to M R Wallace.

At least 91 records · Page 5Linked to original sources
PubMed1995

Temperament and the hospitalized child.

There is increasing evidence to support that temperament is an important variable in considering approaches to nursing care for the hospitalized child. Nursing admission assessment can be expanded to include temperament data from parent interviews. A number of case studies are highlighted to illustrate the relationship between temperament assessment, nursing interventions, and expected outcomes. It is recommended that pediatric nurses incorporate temperament information in all steps of the nursing process.

Child↗
PubMed1995

Benign neurofibromas in type 1 neurofibromatosis (NF1) show somatic deletions of the NF1 gene.

Neurofibromatosis type 1 (NF1) is one of the most common human autosomal dominant diseases. NF1 is characterized by café-au-lait spots (CLS), axillary freckles and Lisch nodules of the iris. Another hallmark of NF1 is the development of neurofibromas, benign tumours that arise from peripheral nerve sheaths. NF1 patients also have an increased incidence of certain malignant tumours. Malignancies in NF1 are believed to follow the 'two-hit' hypothesis, in which one allele is constitutionally inactivated while the other allele is subsequently inactivated ('second hit') at the somatic level. This hypothesis has not, however, been fully tested in the aetiology of benign neurofibromas. This is a crucial issue since it addresses not only the basic mechanism behind the genesis of neurofibromas, but may also indicate a mechanism common to many or all NF1 features. Using both NF1 intragenic polymorphisms as well as markers from flanking and more distal regions of chromosome 17, we have investigated loss of heterozygosity (LOH) in 22 neurofibromas from five unrelated NF1 patients. Eight of these tumours revealed somatic deletions involving NF1, indicating that inactivation of NF1 is associated with at least some neurofibromas.

Adult↗
PubMed1995

Rethinking CD4+ T cell counts for individuals who recently seroconverted to human immunodeficiency virus.

The distribution of initial CD4+ T lymphocyte counts for individuals who have recently seroconverted to human immunodeficiency virus (HIV) is broad. We review major articles describing CD4 cell counts shortly after documented HIV infection and discuss both the possible sources of variability in these studies and the clinical importance of recognizing that even recently infected patients may have low CD4 cell counts and thus will require therapeutic intervention with antiretroviral agents or prophylactic antibiotics.

Anti-Bacterial Agents↗
PubMed1995

Response of recent human immunodeficiency virus seroconverters to the pneumococcal polysaccharide vaccine and Haemophilus influenzae type b conjugate vaccine.

Antibody responses in recent human immunodeficiency virus (HIV) seroconverters to 2 vaccines were studied. Twenty patients infected with HIV for < 18 months and 15 HIV-seronegative controls were vaccinated with the 23-valent pure polysaccharide pneumococcal vaccine and the Haemophilus influenzae type b (Hib) capsular polysaccharide diphtheria CRM197 protein toxoid conjugate vaccine in separate arms. Despite increased levels of total serum IgG, recent seroconverters and controls showed similar specific IgG responses for 6 of 7 antigens. Baseline levels were equivalent in both groups, as were peak levels of IgG at 1 month to conjugated polysaccharide (Hib), delayed-type hypersensitivity, and pneumococcal capsular serotypes 4, 6B, 12F, and 14. At 6 months, IgG levels were similar for 4 of 7 antigens. Antibody responses to pure pneumococcal capsular polysaccharides and to a protein recall antigen were most often similar among recent seroconverters and seronegative controls. Both total levels and fold-rises of IgG to the Hib conjugate were similar in the 2 groups. Immunization of HIV-infected patients soon after seroconversion rather than later appears to improve antibody responses.

Adult↗
PubMed1995

Two-day oral desensitization to trimethoprim-sulfamethoxazole in HIV-infected patients.

OBJECTIVE: To establish whether an outpatient, 2-day oral desensitization protocol would be both safe and effective in HIV-infected patients with previous trimethoprim-sulfamethoxazole (TMP-SMX) intolerance. DESIGN: A single center trial of TMP-SMX desensitization in HIV-infected patients with prior TMP-SMX hypersensitivity reactions. METHODS: HIV-infected patients with CD4 lymphocyte counts < 250 x 10(6)/l cells or CD4% < 20% with previous non-life-threatening hypersensitivity reactions to TMP-SMX were eligible. The desensitization protocol utilized 40 graduated doses over 36 h; the first 28 doses (7.5 h) of the protocol were given in an outpatient clinic with the remaining doses taken at home. RESULTS: Twenty-seven (60%) of the 45 subjects completed the protocol and were subsequently maintained on daily TMP-SMX without adverse reactions (mean follow-up, 9 months; range, 4-16 months). Patients with CD4 counts < 100 x 10(6)/l cells were just as likely as patients with higher CD4 counts to tolerate the desensitization. No patient required hospitalization for treatment of an adverse reaction. CONCLUSION: Oral desensitization to TMP-SMX in HIV-infected patients is a useful option in the management of patients with advanced HIV disease and prior intolerance to TMP-SMX.

AIDS-Related Opportunistic Infections↗
PubMed1995

Diarrheal disease among military personnel during Operation Restore Hope, Somalia, 1992-1993.

The potential for widespread diarrheal disease was regarded as a substantial threat to U.S. troops participating in the early phases of Operation Restore Hope in Somalia. Outpatient surveillance of 20,859 U.S. troops deployed during the first eight weeks, however, indicated that a mean of only 0.8% (range 0.5-1.2%) of personnel sought care for diarrhea each week, and in three epidemiologic surveys, < 3% of troops reported experiencing a diarrheal illness per week. Despite these low overall attack rates, diarrhea accounted for 16% of 381 hospital admissions and 20% of 245 patients admitted with a temperature > or = 38.5 degrees C. Sixty-one specimens were obtained from inpatients and 52 were obtained from outpatients. Shigella sp. were isolated from 33%, enterotoxigenic Escherichia coli from 16%, Giardia lamblia from 4%, and rotavirus from 1% of 113 stool samples obtained from inpatient (61) and outpatient (52) troops with diarrhea. Bacterial isolates obtained in Somalia were resistant to doxycycline (78%), ampicillin (54%), and sulfamethoxazole (49%), but uniformly sensitive to ciprofloxacin. With the exception of 10 Shigella sonnei isolates that were linked epidemiologically to one eating facility, bacterial pathogens occurred sporadically and demonstrated a wide variation of serotypes and antibiotic sensitivity patterns. Additionally, three of 11 paired sera collected from persons with nausea, vomiting, and watery diarrhea demonstrated a four-fold or greater increase in titer to Norwalk virus antibody. These data indicate that large outbreaks of diarrheal disease did not occur; however, highly drug-resistant enteric bacteria, and to a lesser extent viral and parasitic pathogens, were important causes of morbidity among U.S. troops in Somalia.

Acute Disease↗
PubMed1995

Dengue fever in U.S. troops during Operation Restore Hope, Somalia, 1992-1993.

Dengue fever (DF) was considered to be a potential cause of febrile illness in U.S. troops deployed to Somalia during Operation Restore Hope in 1992-1993. A prospective study of hospitalized troops with fever and a seroepidemiologic survey of 530 troops were conducted. Among 289 febrile troops hospitalized, 129 (45%) did not have an identified cause of their fever. Dengue (DEN) virus was recovered from 41 (43%) of 96 of these patients by inoculation of admission sera into C6/36 cell cultures. Thirty-nine (41%) of the isolates were identified as DEN-2 and two (2%) as DEN-3 by an indirect immunofluorescent antibody assay. An additional 18 (49%) of 37 culture-negative cases were shown by immunoglobulin M (IgM) antibody capture enzyme-linked immunosorbent assay to have anti-DEN virus antibody. All identified DF cases recovered within 1-2 weeks; no case of dengue hemorrhagic fever or shock syndrome was observed. A seroepidemiologic survey of a unit (n = 494) with 17 culture or serologically identified DF cases and a 13% attack rate of unidentified febrile illness revealed a 7.7% prevalence of anti-DEN virus IgM antibody. Failure to use bed nets was the only identified risk factor for DEN infection (adjusted odds ratio = 2.2, 95% confidence interval = 1.4-3.0). These data indicate that DF was an important cause of febrile illness among US troops in Somalia, and demonstrate the difficulties in preventing DEN infection in troops operating in field conditions.

Adult↗
PubMed1995

Identification of a yeast artificial chromosome clone spanning a translocation breakpoint at 7q32.1 in a Smith-Lemli-Opitz syndrome patient.

Smith-Lemli-Opitz syndrome (SLOS) is a mental retardation/multiple congenital anomaly syndrome. The gene(s) involved has not been mapped or cloned, but, recently, a biochemical abnormality in cholesterol biosynthesis has been shown to occur in most SLOS patients. The defect is suspected to occur in the penultimate step of the cholesterol pathway, involving the enzyme 7-dehydrocholesterol reductase, which has not been isolated. On the basis of the hypothesis that a de novo balanced translocation [t(7;20)(q32.1;q13.2)] in an SLOS patient directly interrupts the SLOS gene, positional cloning techniques are being employed to localize and identify the SLOS gene. We report the identification of a chromosome 7-specific YAC that spans the translocation breakpoint, as detected by FISH. This is the first study narrowing a candidate SLOS region and placing it on physical and genetic maps of the human genome.

Abnormalities, Multiple↗
PubMed1994

Malaria in US Marines returning from Somalia.

OBJECTIVE: To identify malaria in US Marines returning from Somalia and to determine their compliance with chemoprophylaxis. DESIGN: Case series. SETTING: The US Navy health care system. PATIENTS: Consecutive sample of 106 US Marines diagnosed with malaria after returning from Somalia in 1993. MAIN OUTCOME MEASURES: Identification of the incidence and clinical features of imported malaria. Determination of compliance with chemoprophylaxis in this cohort. RESULTS: As of December 20, 1993, there were 112 cases of imported malaria in 106 US Marine Corps personnel returning from Somalia. Plasmodium vivax accounted for 97 (87%) of 112 malaria cases, and Plasmodium falciparum accounted for eight (7%) of 112 cases. Mixed infection with P vivax and P falciparum was noted in six (5%) of 112 cases, and a single case of Plasmodium malariae was identified. Patients with P falciparum malaria were diagnosed a mean of 20.9 days (range, 1 to 82 days) after returning to the United States compared with 91.8 days (range, 7 to 228 days) for P vivax infection (P < .0001). The self-reported chemoprophylaxis compliance rate was 56%; however, only 45 (50%) of 90 patients were given an optimal chemoprophylaxis regimen. CONCLUSIONS: Noncompliance with personal protective measures and chemoprophylaxis contributed to the largest outbreak of imported malaria in US military personnel since the Vietnam conflict. Since military personnel frequently go on leave after deployment, health care providers throughout the United States must be aware of the presence of imported malaria from Somalia.

Cohort Studies↗
PubMed1994

Elephant man's disease.

On the page of illustrations accompanying the review of Ann Shelby Blum's Picturing Nature (10 Dec., p. 1753), the caption for the illustration from Thomas Say's American Conchology (lower left) erroneously included the names of species not represented in the plate reproduced; all four specimens shown represent Paludina decisa.

Humans↗
PubMed1994

Breast cancer incidence, penetrance and survival in probable carriers of BRCA1 gene mutation in families linked to BRCA1 on chromosome 17q12-21.

Eight breast cancer pedigrees with a high probability of containing individuals with the BRCA1 gene mutation (odds 79.2-99.9 per cent) were identified through genetic linkage analysis using probes located within q12-22 on the long arm of chromosome 17. Some 102 female relatives were successfully typed with one or both of adjacent markers D17S588 and D17S579, and 41 were probable non-BRCA1 mutation carriers. Of the remaining 61 women classified as probable BRCA1 carriers, breast cancer was diagnosed in 35. As expected from epidemiological segregation analysis studies, 13 of these had bilateral disease. Approximately two-thirds of women unaffected by malignancy and alive at the time of observation were non-BRCA1 carriers. Lifetime disease penetrance of the BRCA1 gene was 88 per cent and this plateau was reached earlier (by age 65 years) than that estimated in segregation analysis. The survival curve of patients with breast cancer was less steep in BRCA1 gene carriers than that in the general population; 5-, 10- and 20-year survival rates unadjusted for non-cancer deaths were 83, 63 and 41 per cent respectively. The 5-year survival rate was significantly higher in BRCA1 carriers than that in an age-matched Scottish population (P < 0.05).

Adult↗
PubMed1994

Two NF1 mutations: frameshift in the GAP-related domain, and loss of two codons toward the 3' end of the gene.

Neurofibromatosis type 1 (NF1) is one of the most common autosomal dominant disorders, and is due to mutations within the NF1 gene on chromosome 17q11.2. Only the middle 400 amino acids of the associated protein (neurofibromin) have a known function, comprising a GTPase-activating-protein (GAP) domain. The large gene size and the fact that approximately half of cases are due to new mutation render mutation analysis difficult. NF1 direct mutation characterization is important for development of DNA diagnostic procedures, analysis of phenotype/genotype correlations, and delineation of functions for specific domains of neurofibromin. We report two mutations detected using PCR amplification of individual exons followed by heteroduplex analysis. One is a single base deletion in exon 24 which is predicted to result in a protein truncated early in the GAP-related domain. The other is a 6-bp deletion in exon 39 which is predicted to result in loss of two amino acids in the mature protein near the carboxy-terminus. The exon 24 mutant allele was shown to be expressed by RNA PCR analysis. The exon 39 mutation suggests that those two amino acids are important in neurofibromin function, perhaps indicating a functional domain.

Adolescent↗