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Biomedical subjects

L H Harrison

Publications and source records attributed to L H Harrison.

At least 55 records · Page 3Linked to original sources
PubMed1998

Protective efficacy of a live attenuated vaccine against Argentine hemorrhagic fever. AHF Study Group.

Argentine hemorrhagic fever (AHF), caused by the arenavirus Junin, is a major public health problem among agricultural workers in Argentina. A prospective, randomized, double-blind, placebo-controlled, efficacy trial of Candid 1, a live attenuated Junin virus vaccine, was conducted over two consecutive epidemic seasons among 6500 male agricultural workers in the AHF-endemic region. Twenty-three men developed laboratory-confirmed AHF during the study; 22 received placebo and 1 received vaccine (vaccine efficacy 95%; 95% confidence interval [CI], 82%-99%). Three additional subjects in each group developed laboratory-confirmed Junin virus infection associated with mild illnesses that did not fulfill the clinical case definition for AHF, yielding a protective efficacy for prevention of any illness associated with Junin virus infection of 84% (95% CI, 60%-94%). No serious adverse events were attributed to vaccination. Candid 1, the first vaccine for the prevention of illness caused by an arenavirus, is safe and highly efficacious.

Adolescent↗
PubMed1998

Serotype distribution of invasive group B streptococcal isolates in Maryland: implications for vaccine formulation. Maryland Emerging Infections Program.

Invasive group B streptococcal (GBS) infection is a major health problem among infants and adults. The formulation of GBS vaccines depends on knowledge of the GBS serotype distribution. Serotype V GBS infection appears to have recently emerged, suggesting that the serotype distribution changes over time. GBS isolates from 210 pediatric patients, 23 pregnant women, and 314 nonpregnant adults with invasive infection in Maryland were studied. The predominant serotypes from infants with early-onset disease were as follows: serotype III, 38% of isolates; serotype Ia, 36%; serotype V, 13%; and serotype II, 11%. Although the majority (60%) of isolates among infants with late-onset infection were serotype III, serotype Ia (23%) was also common. The predominant serotype among isolates from nonpregnant adult patients was serotype V, accounting for 29% of the isolates. The serotype distribution differs between pediatric patients and adults and is changing over time. The inclusion of a relatively small number of serotypes in a GBS vaccine could provide protection against the vast majority of isolates.

Adult↗
PubMed1998

Antibody responses in invasive group B streptococcal infection in adults.

Nonpregnant adults with group B streptococcus bacteremia were identified by active surveillance in three hospitals. Serum samples collected within 2 days of the time of blood culture were assayed for IgG antibodies to the capsular polysaccharide of the infecting strain: serotype Ia (3 isolates), III (5 isolates), or V (4 isolates). In 7 of 12 bacteremia episodes, the serum level of IgG to the infecting isolate was > or = 3.5 microg/mL, higher than the 1-2 microg/mL level thought to be protective in neonates. Among selected acute-phase sera, 4 of 5 that contained > or = 3.5 microg/mL specific IgG mediated efficient opsonophagocytic killing of the corresponding group B streptococcus isolate in vitro. High levels of specific antibodies during the acute phase of invasive group B streptococcus infection in nonpregnant adults may reflect a rapid antibody response to infection or, in some cases, may indicate that susceptibility is due to defects in other immune effectors.

Adult↗
PubMed1998

Coinfection with HTLV-I and HIV: increase in HTLV-I-related outcomes but not accelerated HIV disease progression?

Human T-lymphotropic virus type I (HTLV-I) and HTLV-II have been postulated to accelerate disease progression in patients coinfected with HIV. However, recent evidence suggests that HTLV-II has no effect on HIV disease progression. In addition, it has recently been reported that HIV viral load was not increased in subjects coinfected with HTLV-I, suggesting that the biologic basis for the hypothesis does not exist. Several recent studies in Brazil, however, suggest that coinfection with HTLV-I and HIV has substantial medical consequences. For example, coinfection was associated with a higher CD4 lymphocytes count following adjustment for HIV viral load or HIV clinical stage. In addition, coinfected subjects have a high prevalence of clinical significant myelopathy. The effect of other putative viruses as cofactors in HIV disease progression is also discussed.

Brazil↗
PubMed1998

RSV-associated hospitalizations in Alaska Native infants.

PURPOSE: Retrospective reviews for 1986-1992 suggested that Alaska Native children experience high rates of respiratory syncytial virus (RSV)-associated hospitalization; however, the epidemiology of RSV infections has been poorly characterized. METHODS: A prospective hospital-based surveillance study was undertaken to determine rates of RSV-associated hospitalization in Alaska Native children < 36 months from the Yukon-Kuskokwim Delta. RESULTS: During the first study year, October 1993 to September 1994, there were 40 RSV cases (hospitalization rate, 53/1,000 infants < 1 year of age); however, during the second year, October 1994 to September 1995, there were 251 RSV cases (hospitalization rate, 294/1,000 infants). An unusually high proportion, 12%, of RSV cases were < 1 month of age. Disease severity was higher for children with a history of prematurity, heart, or lung disease (p = .001, X2 analysis). Of 255 cell cultures during 1994-1995, 190 were RSV-positive, 11 were positive for influenza, 4 for adenovirus, and 1 for parainfluenza. This study demonstrates wide seasonal variation in a population with an extremely high RSV hospitalization rate; increased disease severity associated with young age and pre-existing medical conditions; and co-circulation of RSV with other viruses.

Alaska↗
PubMed1997

Bacterial meningitis in the United States in 1995. Active Surveillance Team.

BACKGROUND: Before the introduction of the conjugate vaccines, Haemophilus influenzae type b was the major cause of bacterial meningitis in the United States, and meningitis was primarily a disease of infants and young children. We describe the epidemiologic features of bacterial meningitis five years after the H. influenzae type b conjugate vaccines were licensed for routine immunization of infants. METHODS: Data were collected from active, population-based surveillance for culture-confirmed meningitis and other invasive bacterial disease during 1995 in laboratories serving all the acute care hospitals in 22 counties of four states (total population, more than 10 million). The rates were compared with those for 1986 obtained by similar surveillance. RESULTS: On the basis of 248 cases of bacterial meningitis in the surveillance areas, the rates of meningitis (per 100,000) for the major pathogens in 1995 were Streptococcus pneumoniae, 1.1; Neisseria meningitidis, 0.6; group B streptococcus, 0.3; Listeria monocytogenes, 0.2; and H. influenzae, 0.2. Group B streptococcus was the predominant pathogen among newborns, N. meningitidis among children 2 to 18 years old, and S. pneumoniae among adults. Pneumococcal meningitis had the highest case fatality rate (21 percent) and in 36 percent of cases was caused by organisms that were not susceptible to penicillin. From these data, we estimate that 5755 cases of bacterial meningitis were caused by these five pathogens in the United States in 1995, as compared with 12,920 cases in 1986, a reduction of 55 percent. The median age of persons with bacterial meningitis increased greatly, from 15 months in 1986 to 25 years in 1995, largely as a result of a 94 percent reduction in the number of cases of H. influenzae meningitis. CONCLUSIONS: Because of the vaccine-related decline in meningitis due to H. influenzae type b, bacterial meningitis in the United States is now a disease predominantly of adults rather than of infants and young children.

Adolescent↗
PubMed1997

HIV viral load and CD4+ lymphocyte counts in subjects coinfected with HTLV-I and HIV-1.

Reports indicate that there is a dissociation between markers of HIV disease progression and clinical stage among subjects coinfected with human T-cell lymphotropic virus type I (HTLV-I) and HIV. HTLV-I coinfection does not appear to affect HIV viral load, currently considered to be the best marker of HIV disease progression. We measured HIV RNA levels in stored serum samples from 23 subjects with coinfection and 92 subjects with HIV single infection and examined the correlation with the CD4+ lymphocyte count. Subjects were recruited from an ongoing HIV cohort study in Rio de Janeiro, Brazil. In both groups, CD4+ lymphocyte counts declined with increasing levels of HIV RNA. In a linear regression analysis adjusting for HIV RNA serum level, coinfected individuals had an estimated 78% higher CD4+ lymphocyte count than those with single infection. Simultaneous adjustment for beta2-microglobulin level increased the difference, with coinfected individuals having 146% (p = 0.005, 95% CI: 32% to 359%) higher CD4+ counts. These data suggest that the higher CD4+ lymphocyte counts associated with coinfection do not provide immunologic benefit and may reflect HTLV-I-associated nonspecific lymphocyte proliferation. The results of this and other studies suggest that the CD4+ count cutoff values used in making clinical decisions in HIV infection may not be appropriate in coinfection. As with HIV single infection, HIV virus load may be the optimal surrogate marker for subjects with coinfection.

Acquired Immunodeficiency Syndrome↗
PubMed1997

Craniofacial resection for malignant tumors involving the anterior skull base.

OBJECTIVES: To review our experience with craniofacial resection for malignant neoplasms of the anterior skull base and report long-term results, and to analyze survival in terms of the overall experience, tumor histological diagnoses, and tumor extent. Also, to report complications of this surgical procedure. DESIGN: Retrospective review. SETTING: Tertiary cancer facility. PATIENTS: We evaluated 115 consecutive patients undergoing craniofacial resection for malignant neoplasms involving the anterior skull base. Forty-five (39%) presented with recurrent or persistent disease after prior therapy. MAIN OUTCOME MEASURES: Survival was evaluated with the Kaplan-Meier product limit method and comparisons between individual subgroups were performed using the log-rank test. RESULTS: The operative mortality rate was 3.5%. Major complications occurred in 40 patients (35%). For the entire group, disease-specific survival rates were 58% and 48% at 5 and 10 years, respectively. The highest survival rate was observed in patients with esthesioneuroblastoma and lowest in those with mucosal melanoma. Survival was significantly better for those whose tumors could be excised with a limited resection in comparison with those requiring an extended procedure (P = .009). CONCLUSIONS: A 23-year experience with craniofacial resection performed for malignant tumors involving the anterior skull base confirms the durable results obtained with this intervention. The diversity of histological diagnoses, site of origin, extent of tumor invasion, and impact of prior therapy hampers any attempt at reporting meaningful survival statistics for comparison with other series or other means of treatment.

Adenocarcinoma↗
PubMed1997

Carbon dioxide field flooding minimizes residual intracardiac air after open heart operations.

Transesophageal echocardiographic studies were used to monitor the presence of air bubbles in the heart after open heart operations. After cardiac valvular procedures all 22 patients managed with careful deairing procedures had persistence of air bubbles for at least 30 minutes and usually for 45 minutes. In 56 patients with CO2 field flooding, all foam disappeared in less than 1 minute in 48 patients and the remaining 8 had complete disappearance in 1 to 24 minutes. These observations demonstrate the ineffectiveness of the usual deairing maneuvers and the effectiveness of CO2 field flooding in displacing air.

Air↗
PubMed1997

Human T cell lymphotropic virus type I does not increase human immunodeficiency virus viral load in vivo.

Human T lymphotropic virus type I (HTLV-I) can increase human immunodeficiency virus (HIV) replication in vitro, and several studies suggest that HTLV-I accelerates the progression of HIV infection. To determine whether HTLV-I enhances HIV replication in vivo, a case-control study was done of serum HIV viral load, using polymerase chain reaction, in 23 subjects with HTLV-I/HIV coinfection and 92 control subjects with HIV single infection. The geometric mean serum RNA level was 11,482 copies/mL in the coinfected group and 13,804 in the single-infection group (P = .57), a result that did not change after adjustment for zidovudine use and CD4 cell count. Among subjects with advanced HIV infection, there was a trend toward higher viral load among singly infected subjects. HTLV-I did not appear to increase HIV plasma RNA levels in subjects with coinfection. These results do not provide a biologic basis for the hypothesis that HTLV-I accelerates the course of HIV infection.

Adult↗
PubMed1997

Myelopathy among Brazilians coinfected with human T-cell lymphotropic virus type I and HIV.

OBJECTIVE: To determine whether subjects coinfected with HTLV-I and HIV have a higher frequency of myelopathy than subjects singly infected with HIV. DESIGN: A prospective, nested case-control study of HTLV-I and HIV coinfected (cases) and HIV singly infected adults (controls) participating in a prospective HIV cohort study at a university hospital outpatient HIV clinic in Rio de Janeiro, Brazil. MEASUREMENTS: Subjects were evaluated for evidence of myelopathy by a neurologist unaware of their HTLV serologic status. Patients with at least two pyramidal signs, such as paresis, hypertonicity or spasticity, hyperreflexia, clonus, diminished or absent superficial reflexes, or the presence of pathologic reflexes (e.g., Babinski or Hoffmann), were defined as having myelopathy. Myelopathy severity was quantified using the Kurtzke Functional Disability Scale (FDS); patients with FDS scores > or = 4 were considered to have significant myelopathy. Selected patients with myelopathy underwent lumbar puncture for the evaluation of intrathecal synthesis of HTLV-I antibodies. RESULTS: Of 15 coinfected subjects, 11 (73%) had evidence of myelopathy versus 10 of 62 subjects (16%) with HIV single infection (adjusted odds ratio [OR] = 13.0, p = 0.00002). When only myelopathy patients with FDS scores of > or = 2 or > or = 4 were included, the association between coinfection and the presence of myelopathy remained (OR = 7.3, p = 0.0003 for scores > or = 2; and OR = 8.9 for scores > or = 4, p = 0.04). In addition, a higher proportion of coinfected subjects had peripheral neuropathy (40%) than controls (16%) (OR = 3.5, p = 0.07). CONCLUSION: Coinfection with HTLV-I was strongly associated with myelopathy among subjects infected with HIV. The relative contribution of HTLV-I versus HIV in the pathogenesis of coinfection-associated myelopathy is not known. Coinfection may also be associated with peripheral neuropathy. Further studies are needed to elucidate the mechanisms of coinfection-associated neurologic conditions.

Adult↗
PubMed1996

Monovalent latex agglutination reagents for the diagnosis of nonmeningitic pneumococcal infection.

The pneumococcus is a leading cause of serious bacterial infection worldwide. Given the difficulties with available assays for the diagnosis of invasive nonmeningitic pneumococcal infection, we evaluated monovalent slide latex agglutination reagents among patients with blood culture-confirmed pneumococcal infection and control patients in Baltimore, Maryland, USA; São Paulo, Brazil; and Cairo, Egypt. Among 50 patients with invasive nonmeningitic pneumococcal infection, 23 had a positive urine test for a sensitivity of 46% (95% confidence intervals of 32% and 61%). Among 39 healthy children, 36 had a negative assay, for a specificity of 92% (95% confidence intervals of 78% and 98%). Among 80 children with pneumonia without a positive blood culture for Streptococcus pneumoniae, the specificity was 88% (95% confidence intervals of 78% and 94%). Although the assay was fairly specific, the positive predictive value using optimistic assumptions was only 73%-83%. This study suggests that this assay has a sensitivity and positive predictive value that may limit its value in some settings.

Child, Preschool↗
PubMed1996

Shawl lapel aortoplasty.

We describe a simple method of remodeling an ascending aorta that has dilated in response to a stenotic aortic valve. It provides excellent exposure for valve replacement and avoids the use of substantial prosthetic material in effecting a secure, facile closure.

Aorta↗
PubMed1996

Resistance patterns of Streptococcus pneumoniae and Haemophilus influenzae isolates recovered in Egypt from children with pneumonia. The Antimicrobial Resistance Surveillance Study Group.

Treatment of childhood pneumonia in developing countries requires knowledge of susceptibility patterns for Streptococcus pneumoniae and Haemophilus influenzae. Between October 1991 and April 1993, a surveillance survey of antimicrobial resistance was performed at two fever hospitals in Egypt; nasopharyngeal swab and blood specimens obtained from 1,635 children with pneumonia were cultured for these organisms. Susceptibility testing of these organisms was performed. At least one of these organisms was isolated from nasopharyngeal swab specimens from 73% of the children; 3.7% of blood cultures were positive. For S. pneumoniae strains, 70.9% of nasopharyngeal isolates were calculated to be susceptible to penicillin vs. 77.6% of blood isolates; the percentages of isolates susceptible to co-trimoxazole were 73.0% and 75.0%, respectively. For H. influenzae strains, 93.0% of nasopharyngeal isolates were calculated to be susceptible to ampicillin vs. 100% of blood isolates; the percentages of isolates susceptible to co-trimoxazole were 84.9% and 100%, respectively. Although most S. pneumoniae and H. influenzae strains associated with childhood pneumonia in Cairo were susceptible to penicillins and co-trimoxazole, antimicrobial resistance did not occur.

Ampicillin↗
PubMed1996

Findlay implantable two-stage centrifugal pump.

The Findlay centrifugal pump is unique in its two-stage pumping mechanisms and in its complementary interrelationship of the stages to each other and to the exit system, and it forms an extremely efficient unit. The first stage is a lift force pump as an inlet. The second and major stage is a shear force pump. Twenty-six prototypes, many multiply modified, have been hand fabricated, and most have had classic pump function analyses. Six pumps have demonstrated minimal hemolysis (3.5-5 h). At modest rotation speeds, it pumps water up to 10 L/min. Forty-four acute studies in normal dogs have been performed with the Findlay pump in a ventricular assist system. Blood flows through the pump ranged from 1.2 to 4.5 L/min. The conclusion is that the Findlay pump has the ability to operate with low blood damage, performs at acceptable rotational speed with reasonable hydraulic and mechanical efficiency, and is small and implantable.

Animals↗