Biomedical subjects

D Sack

Publications and source records attributed to D Sack.

At least 19 recordsLinked to original sources

PubMed2003

DHEA treatment of Alzheimer's disease: a randomized, double-blind, placebo-controlled study.

OBJECTIVE: To compare the efficacy and tolerability of dehydroepiandrosterone (DHEA) vs placebo in AD. METHOD: Fifty-eight subjects with AD were randomized to 6 month's treatment with DHEA (50 mg per os twice a day; n = 28) or placebo (n = 30) in a multi-site, double-blind pilot trial. Primary efficacy measures assessed cognitive functioning (the AD Assessment Scale-Cognitive [ADAS-Cog]) and observer-based ratings of overall changes in severity (the Clinician's Interview-Based Impression of Change with Caregiver Input [CIBIC-Plus]). At baseline, 3 months, and 6 months, the ADAS-Cog was administered, and at 3 and 6 months, the CIBIC-Plus was administered. The 6-month time point was the primary endpoint. RESULTS: Nineteen DHEA-treated subjects and 14 placebo-treated subjects completed the trial. DHEA was relatively well-tolerated. DHEA treatment, relative to placebo, was not associated with improvement in ADAS-Cog scores at month 6 (last observation carried forward; p = 0.10); transient improvement was noted at month 3 (p = 0.014; cutoff for Bonferroni significance = 0.0125). No difference between treatments was seen on the CIBIC-Plus at either the 6-month or the 3-month time points. CONCLUSIONS: DHEA did not significantly improve cognitive performance or overall ratings of change in severity in this small-scale pilot study. A transient effect on cognitive performance may have been seen at month 3, but narrowly missed significance.

Aged↗

PubMed2003

Navy hearing conservation program: hearing threshold comparisons to Navy SEALS and divers.

The study examined hearing threshold for Navy special operations personnel (SEALS (Sea-Air-Land): N = 212; divers: N = 165). Hearing threshold values were obtained and age adjusted using Mantel Haenzel Weighted odds ratio (MHOR) to compare with information in the Navy Hearing Conservation Database. For any threshold above 20 dB in the 500 through 3000 Hz range, the SEALS were significantly less at risk (MHOR = 0.54, p = 0.022) in the right ear, while the divers were significantly less at risk in the left ear (MHOR = 0.61, p = 0.047). For hearing thresholds at 4000 Hz above 40 dB, SEALS were significantly more at risk in both left ear (MHOR = 2.03, p = 0.0043) and right ear (MHOR = 2.58, p = 0.000089), while divers were not different. Risk assessment based on these findings must consider the multiple exposure hazards and critical mission profiles for the Navy special operations personnel. Requirements for mission accomplishment in hazardous environments may deem these risks acceptable.

Adolescent↗

PubMed2001

Randomized, double-blind study in healthy adults to assess the boosting effect of Vaqta or Havrix after a single dose of Havrix.

A randomized, double-blind, multicenter study was conducted to investigate the boosting effect of Vaqta or Havrix in 537 healthy adults 18-53 years of age who had received a single dose of Havrix either 24 or 52 weeks earlier. Subjects were randomized in a 2 : 1 ratio to receive either Vaqta or Havrix for their second dose of vaccine and followed for clinical reactions for 14 days after dose 2 was administered. Serum samples were collected immediately before dose 2 was administered and again 4 weeks later and evaluated for hepatitis A antibody (modified hepatitis A virus antibody assay). The booster response rate after administration of the second dose of either vaccine was similar (86.1% for Vaqta vs. 80.1% for Havrix). The geometric mean titers were also similar: 3274 mIU/mL (95% confidence interval [CI], 2776-3858) for Vaqta versus 2423 mIU/mL (95% CI, 1911-3074) for Havrix. The proportion of subjects who reported > or =1 injection-site adverse experiences was lower in the patients receiving Vaqta than in those receiving Havrix (36.6% vs. 59.7%; P<.001). The results of this study indicate that a regimen of Havrix followed by Vaqta is generally well tolerated and highly immunogenic.

Adolescent↗

PubMed2000

A method for monitoring the health of US Navy submarine crewmembers during periods of isolation.

BACKGROUND: With the expansion of the manned space program, an essential consideration in planning is the medical support necessary for long-term missions. Information on analogous populations serving in isolated and/or contained environments may be useful in predicting health risks for astronauts. METHODS: The present study evaluates rates of health events that occur in a highly screened, healthy military population during periods of isolation. A centralized database was designed to collect medical encounter data from U.S. Navy submarines and contains demographic information, crew rosters for each patrol, medical encounter notes, accident reports, medical evacuation reports, vital signs and laboratory data. The population included in the present analysis is composed of crewmembers aboard 136 submarine patrols between January 1, 1997 and December 31, 1998. RESULTS: A total of 2,044 initial visits to medical staff and 973 re-visits for the same condition were recorded during these patrols. Potentially mission-impacting medical events reported among crewmembers were rare (i.e., among a crew of 10 individuals, only 1-2 medical events would be expected to occur during a 100 d-mission). The most common category of medical events was injury, followed by respiratory illnesses (URIs), skin problems (minor infections, ingrown toenail), symptoms and ill-defined conditions, digestive disorders, infectious conditions, sensory organ problems (ear and eye), and musculoskeletal conditions.

Adult↗

PubMed1998

Filmless medical imaging: experiences of the Massachusetts General Hospital.

As the concept of picture archival communication systems (PACS) gathers momentum, the vision of a filmless digital department and digital image management has become a reality. This report will discuss the experiences of a major health-care institution with implementation of a large-scale PACS. Specifically, we discuss success with a modular, nonproprietary, multivendor solution that offers flexibility and state of the art functionality at our institution.

Hospitals, General↗

PubMed1998

The primary interpretation workstation: information beyond image data.

With the advent of picture archival and communication systems (PACS), the importance of design surrounding primary review workstations has become apparent. To help acceptance of filmless medical imaging, workstations must be developed that serve the needs of both radiologists and referring clinicians. This report will discuss integral requirements of workstation design, including information creation, medical management, medical knowledge, and enabling technologies.

Data Display↗

PubMed1995

Impaired immune response to natural infection as a correlate of vaccine failure in a field trial of killed oral cholera vaccines.

In a field trial carried out in 1985 in Matlab, Bangladesh, the authors evaluated whether subjects who developed Vibrio cholerae 01 infections during the first year after earlier receipt of B subunit-killed whole cell (BS-WC) or killed whole cell-only (WC) oral cholera vaccines exhibited deficient serum vibriocidal immune responses to these infections. After severe V. cholerae 01 infections (n = 70) in subjects > 5 years of age, the age group in which both vaccines were efficacious, a 6.5 geometric mean-fold rise of serum vibriocidal antibodies was observed among vaccinees, compared with an 18.6 geometric mean-fold rise in placebo-recipients (p < 0.01). Depressions of serum vibriocidal responses among vaccinees were even more marked after asymptomatic infections (n = 30): a 1.1 geometric mean-fold rise in vaccinees versus a 5.9 geometric mean-fold rise in placebo-recipients (p < 0.01). The authors conclude that subjects who failed to be protected by BS-WC and WC, despite being in the age group for which these vaccines were protective, exhibited poor immune responses even to the vigorous stimulus of natural infection. These findings raise the possibility that immune hyporesponsiveness may limit the potential efficacy attainable by cholera vaccines in populations with endemic cholera.

Administration, Oral↗

PubMed1995

Impact of infection by Helicobacter pylori on the risk and severity of endemic cholera.

To evaluate the relationship between Helicobacter pylori infection and the subsequent risk and severity of endemic Vibrio cholerae O1 diarrhea among rural Bangladeshis, 285 children and adults with cholera (cases) and 881 contemporaneously selected community controls were studied. Cases and controls were contrasted for H. pylori infection, as manifested by serum IgG anti-H. pylori antibodies. Although the overall risk of cholera was not significantly increased among H. pylori-infected subjects, the risk of cholera of life-threatening severity was significantly elevated (relative risk [RR] = 1.61; 95% confidence interval [CI] = 1.07-2.42). A significant increase in the risk of severe cholera was seen in subjects who lacked natural serum vibriocidal antibodies (RR = 2.88; 95% CI = 1.28-6.48) but not in those with such antibodies. Thus, H. pylori infection was associated with a significant increase in the risk of life-threatening cholera, but only among persons lacking natural vibriocidal immunity.

Adolescent↗

PubMed1994

Decision making during a phase III randomized controlled trial.

Experiments such as clinical trials should be carried out with specific objectives. For example, in a trial designed to prevent disease, specific considerations should be made concerning the impact of the trial on the health of the target population, including the participants in the trial. These objectives should be assessed continually in light of data accumulating from the trial. Accumulating evidence should be judged in the context of changing circumstances external to the trial, and the trial's design possibly modified. An important type of modification is stopping the trial. This is a sequential decision problem that can be addressed using a Bayesian approach and the methods of dynamic programming. As an example we consider a vaccine trial for the prevention of haemophilus influenzae type b. The objective we consider is minimizing the number of cases of this disease in a Native American population over a specified horizon. We assess the prior probability distribution of vaccine efficacy. We also assess the probability of regulatory approval for widespread use of the vaccine, depending on the data presented to the regulatory officials. In deciding whether to continue the trial we weigh the impact of the possible future results by their (predictive) probabilities. We address the sensitivity of the optimal stopping policy to the prior probability distribution, to the assessed probability of regulatory approval, and to the horizon.

Bayes Theorem↗

PubMed1993

Prevalence of shigellosis and other enteric pathogens in a zoologic collection of primates.

An epidemiologic study of shigellosis was the preliminary step in the formulation of a plan for the control of devastating infectious diseases in nonhuman primates at the National Zoological Park. Data were collected from primate groups with enzootic shigellosis and included the following species: white-cheeked and siamong gibbons (Hylobates concolor and H syndactylies); lion-tailed, celebes, and Barbary macaques (Macaca silenus, M nigera, and M sylvanus); black and white colobus monkeys (Colobus guerzea); grey-cheeked mangabeys (Cerecocebus albigena); spider monkeys (Ateles susciceps robusuts); ruffed lemurs (Lemur varrigatus); lowland gorillas (Gorilla gorilla); and orangutans (pongo pygmaeus). Data included results of physical examination, proctoscopy with biopsy, fecal parasitologic and cytologic examinations, and bacteriologic culturing of swabbed specimens of rectum and gingiva. Repetitive fecal examinations were subsequently performed and included bacteriologic culturing of fecal specimens for enteropathogenic bacteria and parasites and cytologic examination of feces. Data were collected for a 1-year period from 82 primates, and 14 gibbons were studied intensively. White-cheeked and siamang gibbons shed Shigella flexneri sporadically, but persistently. All gibbons were affected with a mean point prevalence of 30.7% (range 0 to 71%). Shigella flexneri also was isolated from feces of lion-tailed macaques. Shigella sonnei was isolated from feces of grey-cheeked mangabeys, celebes macaques, and spider monkeys.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

PubMed1993

Clearance of Shigella flexneri carriers in a zoologic collection of primates.

In 1990, a high prevalence of Shigella flexneri was documented in the gibbon population at the National Zoological Park. The enzootic strain had been determined to be resistant to most antibiotics and had been responsible for animal deaths. Prevalence of Shigella spp was high in the entire primate population. To address the clinical problem, eradication was attempted by use of enrofloxacin. Facilities disinfection comprised a large part of Shigella clearance efforts. After the clearance protocol was completed gibbons, vs other primate species, were closely monitored for 16 months by subjecting their feces to bacteriologic culturing. The program was successful, with eradication of the problematic strain of S flexneri. However, 10 to 12 months after completion of treatments, S sonnei was isolated from feces of 3 animals living in the same housing facility.

Animals↗

PubMed1993

The design and analysis of cholera vaccine trials: recent lessons from Bangladesh.

The recent spread of cholera to Latin America, together with the persistent burden of this disease in Asia and Africa, have stimulated efforts to evaluate new cholera vaccines in field settings. Although the standard experimental paradigm for vaccine field trials is well established, the success of these trials will also depend on suitable consideration of the epidemiology of cholera and of cholera vaccination in the setting under study. Epidemiological studies done in Bangladesh emphasize the importance of appreciating the poorly predictable, multifocal occurrence of cholera in estimating a probable incidence of cholera for a field trial. They also underscore how the filtering effect of enrolling subjects into a prospective trial can dramatically reduce the available population for study, and can yield a study sample whose expected risk of cholera differs markedly from that for the source population. Finally, the data highlight the subtle effects that the mode of surveillance and the choice of an outcome definition can have upon protective efficacy, and emphasize the need for subgroup analyses that address the distinctive variations in vaccine protection that may occur in subjects differing in age and in ABO blood groups, and in subjects exposed to classical versus El Tor cholera.

ABO Blood-Group System↗

PubMed1993

Health status of pesticide applicators: postural stability assessments.

Postural sway testing was performed on 37 pesticide-exposed workers and 35 nonexposed subjects. All subjects were asymptomatic. When ratios of sway measurements in different test conditions were investigated, total length of sway was significantly different between groups (P = .0001). Weight/height (P = .0006), exposure to pesticides (P = .0215), recent organophosphate exposure (P = .0391), and plasma cholinesterase level (P = .1537) were associated with increased body sway. The pattern of sway performance suggested a proprioceptive impairment, well compensated by visual cues, potentially attributable to pesticide exposure. This finding is of unclear clinical significance because results of neurologic examinations and nerve conduction studies that were reported separately did not show evidence of neuropathy. Postural sway testing is a simple, sensitive, noninvasive, and reproducible technique to evaluate subtle neurologic dysfunction. These findings are preliminary. Further studies are required to validate the findings and, if confirmed, to explore their functional or clinical significance.

Adult↗

PubMed1992

The perioperative use of blood components during heart and heart-lung transplantation.

Perioperative blood usage during 172 heart transplants (HTs) and 100 heart-lung transplants (HTLs) performed at the same center during 1986 and 1989 was reviewed. In 1986, 79 HTs were performed with a median (interquartile range) blood component use of 12 (range, 8-20) units, of which 6 (range, 4-8) constituted red cell components. The use of blood components was significantly reduced (p less than 0.05 by the Mann-Whitney U test) in 1989 to 10 (range, 8-20) units, of which red cell components constituted 5 (range, 3-7) units. Fifty HLTs in 1986 used a median (interquartile range) of 25.5 (range, 11.5-53) units of blood components. This use was significantly reduced (p less than 0.05) to a median of 18 (range, 9-29) units in 1989, of which 8 (range, 5-11) were red cell components, 4 (range, 2-8) were units of fresh-frozen plasma, and 5 (range, 0-10) were units of platelets. More blood components were used in patients who had previous cardiothoracic surgery and/or previous transplants; this reached significance in the 1986 HTs (p less than 0.001). Fresh blood was used in only one HT but in 12 (24%) of 1086 HLTs and 4 (8%) of 1989 HLTs. As the indication for fresh blood was excessive bleeding, there was a significantly greater use of blood components in 1989 HLT patients receiving fresh blood than in those not receiving fresh blood (median [range] of 163.5 [62-251] units compared to 15.5 [3-126]).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗

PubMed1992

Marketing CT and MR imaging services in a large urban teaching hospital.

A three-phase marketing program was implemented to increase referrals for examination with computed tomographic (CT) or magnetic resonance (MR) imaging and improve services in an academic radiology department. In the research phase, a data base of 135 referring physicians was developed, and a questionnaire was mailed to 130 physicians. The market research identified three key issues: waiting time to get an appointment, scheduling procedures, and communication of findings. In the implementation phase, additional equipment was installed and a program of expanded appointments, service improvements, and public relations was introduced. In the evaluation phase, 1 year after the completion of phase 2, the effect of the marketing program was measured. The average number of physicians who made referrals per month increased from 609 to 653 (an increase of 7.2% over baseline); the average number of CT and MR examinations performed each month increased by 57.3% and 45.2%, respectively. Referrers' ratings of 10 imaging services improved significantly (P = .02). It is concluded that a well-designed marketing program can boost the productivity of a teaching hospital department.

Appointments and Schedules↗

PubMed1992

Improved radiology film library operations.

An interdisciplinary task force at the authors' institution developed a design for a new film library that placed heavy emphasis on service to its customers. The task force established locations and staffing for "satellite" inpatient film libraries organized by clinical specialties. Inpatient films were not permitted to be taken from the radiology department but were available for 24-hour viewing. Film locations were recorded in the radiology information system. Reorganization led to important improvements in film library operations and in the clinical staff's opinion of film library service. Objective measures of performance, such as the fraction of requested films available for conferences, showed significant improvement (P less than .001). Closer working relationships developed between film librarians, radiologists, and their clinical colleagues. Film library personnel were recruited more easily and stayed on the job longer. Several hundred thousand film-tracking transactions per year were recorded. The authors conclude that decentralization of certain film library activities improved many critical aspects of performance.

Libraries↗

PubMed1991

The efficacy in Navajo infants of a conjugate vaccine consisting of Haemophilus influenzae type b polysaccharide and Neisseria meningitidis outer-membrane protein complex.

BACKGROUND AND METHODS: Several conjugate vaccines against Haemophilus influenzae type b have been developed in the search for one that induces protection even in young infants. We evaluated the safety and efficacy of a conjugate vaccine that links the H. influenzae type b capsular polysaccharide to the outer-membrane protein complex (OMPC) of Neisseria meningitidis serogroup B. We conducted a double-blind, placebo, controlled trial in Navajo infants, who are at high risk for systemic infections caused by H. influenzae type b. The infants were randomly assigned to receive the first dose of vaccine or placebo at 42 to 90 days of age and the second at 70 to 146 days of age. RESULTS: Of the infants in the trial, 2588 were assigned to receive the vaccine and 2602 to receive placebo. The mean follow-up was 269 days in the vaccine group and 267 days in the placebo group. Before the age of 18 months, there was 1 systemic H. influenzae type b infection in the vaccine group, as compared with 22 in the placebo group (P less than 0.001; point estimate of efficacy, 95 percent; 95 percent confidence interval, 72 to 99 percent). Of the 22 H. influenzae type b infections in the placebo group, 13 were meningitis. Among the children who received both doses, there was 1 H. influenzae type b infection in the vaccine group (n = 2056) and 14 in the placebo group (n = 2105) (P less than 0.001; point estimate of efficacy, 93 percent; 95 percent confidence interval, 53 to 98 percent). The single infection in the vaccine group occurred at 15 1/2 months of age in an infant with osteomyelitis. Between the first and second doses there were no H. influenzae type b infections in the vaccine group and eight in the placebo group (P less than 0.005; point estimate of efficacy, 100 percent; 95 percent confidence interval, 41 to 100 percent). CONCLUSIONS: The H. influenzae type b OMPC vaccine, administered at 2 and 4 months of age, is safe and induces a high rate of protection against invasive disease caused by H. influenzae type b in infants under the age of 18 months. Protection begins after the first dose.

Antibody Formation↗

PubMed1989

Measuring cholinergic sensitivity: I. Arecoline effects in bipolar patients.

In a previous study, bipolar patients were found to be more sensitive than controls to induction of rapid eye movement (REM) sleep by the direct muscarinic agonist arecoline. We have replicated this observation in a new group of patients and controls. However, much overlap between groups was seen. Muscarinic supersensitivity appears to be present in some bipolar affective patients, but the REM induction procedure may not be the optimal method for measuring it.

Adult↗