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Biomedical subjects

J A McMillan

Publications and source records attributed to J A McMillan.

At least 19 recordsLinked to original sources
PubMed1999

Effectiveness of influenza vaccine in health care professionals: a randomized trial.

CONTEXT: Data are limited and conflicting regarding the effectiveness of influenza vaccine in health care professionals. OBJECTIVE: To determine the effectiveness of trivalent influenza vaccine in reducing infection, illness, and absence from work in young, healthy health care professionals. DESIGN: Randomized, prospective, double-blind, controlled trial over 3 consecutive years, from 1992-1993 to 1994-1995. SETTING: Two large teaching hospitals in Baltimore, Md. PARTICIPANTS: Two hundred sixty-four hospital-based health care professionals without chronic medical problems were recruited; 49 participated for 2 seasons; 24 participated for 3 seasons. The mean age was 28.4 years, 75% were resident physicians, and 57% were women. INTERVENTION: Participants were randomly assigned to receive either an influenza vaccine or a control (meningococcal vaccine, pneumococcal vaccine, or placebo). Serum samples for antibody assays were collected at the time of vaccination, 1 month after vaccination, and at the end of the influenza season. Active weekly surveillance for illness was conducted during each influenza epidemic period. MAIN OUTCOME MEASURES: Serologically defined influenza infection (4-fold increase in hemagglutination-inhibiting antibodies), days of febrile respiratory illness, and days absent from work. RESULTS: We conducted 359 person-winters of serologic surveillance (99.4% follow-up) and 4746 person-weeks of illness surveillance (100% follow-up). Twenty-four(13.4%) of 179 control subjects and 3 (1.7%) of 180 influenza vaccine recipients had serologic evidence of influenza type A or B infection during the study period. Vaccine efficacy against serologically defined infection was 88% for influenza A (95% confidence interval [CI], 47%-97%; P=.001) and 89% for influenza B (95% CI, 14%-99%; P=.03). Among influenza vaccinees, cumulative days of reported febrile respiratory illness were 28.7 per 100 subjects compared with 40.6 per 100 subjects in controls (P=.57) and days of absence were 9.9 per 100 subjects vs 21.1 per 100 subjects in controls (P=.41). CONCLUSIONS: Influenza vaccine is effective in preventing infection by influenza A and B in health care professionals and may reduce reported days of work absence and febrile respiratory illness. These data support a policy of annual influenza vaccination of health care professionals.

Absenteeism↗
PubMed1999

Long-latency contributions to reciprocal inhibition during various levels of muscle contraction.

Reciprocal inhibition is a functional term and refers to the proportional decrease in antagonist motoneuron activity that accompanies an agonist contraction. A condition-test (C-T) H-reflex paradigm (conditioned stimulus applied to the common peroneal nerve; test reflex elicited by posterior tibial nerve stimulation) was used during: (1) rest, (2) a tonic isometric tibialis anterior (TA) contraction at 10% of its maximal voluntary contraction (MVC) and, (3) a TA contraction at 25% MVC. The purpose of the study was to assess whether or not long-latency contributions to reciprocal inhibition of soleus H-reflexes changed with increasing levels of TA contraction. C-T intervals ranged from 5 to 150 ms. Subjects (n=14) had long-latency inhibition at rest (x = -35.0 +/- 18.7%). This inhibition was enhanced during 10% (x = -46.1 +/- 17.9%; p = 0.17) and 25% MVCs (x = -56.3 +/- 14.0%; p < 0.01). Findings indicate that long-latency contributions to reciprocal inhibition of the soleus motoneuron pool are enhanced with increasing force of TA muscle contraction up to 25% MVC. These results indicate that long-latency contributions to reciprocal inhibition of soleus H-reflexes are not static but rather are task-specific and change in relation to levels of TA muscle activity.

Adult↗
PubMed1998

H-reflex modulations during voluntary and automatic movements following upper motor neuron damage.

OBJECTIVES: It is not known whether similar mechanisms account for the impairments of voluntary movement and automatic postural responses of individuals with spasticity secondary to damage to the sensorimotor cortex and its projections (i.e. upper motor neuron syndrome (UMN)). METHODS: The present study examined changes in soleus H-reflexes preceding and during voluntary tibialis anterior (TA) muscle contraction of standing subjects and during balance platform induced postural perturbations that elicited similar TA muscle contractions. Twenty-two subjects (12 non-disabled; 4 with spastic-type cerebral palsy; 6 with adult-onset cerebral vascular accident) participated in the study. Data were analyzed using ANOVAs and Tukey HSD post-hoc comparison tests to assess the timing and magnitude of soleus H-reflex amplitude changes relative to the onset of TA muscle activation. RESULTS: Results indicated that, regardless of the level of TA activation, soleus H-reflexes of subjects with UMN involvement did not demonstrate inhibition either. during voluntary movements or during automatic postural perturbations. CONCLUSIONS: These findings indicate that postural reflexes, as well as volitional movements, are impaired following UMN damage and that deficits in neural pathways subserving reciprocal inhibition contribute to the impairments.

Adult↗
PubMed1997

Changes in neural modulation and motor control during voluntary movement of older individuals.

BACKGROUND: Changes in the modulation of soleus alpha motoneuron excitability, as assessed by H reflexes, and temporal sequencing of the soleus and tibialis anterior muscles during voluntary ankle dorsiflexions and plantar flexions of young (24.7 +/- 11.5; n = 13) and older (68.7 +/- 5.4; n = 13) subjects were assessed to determine potential neural mechanisms that might contribute to motor control changes associated with aging. METHODS: A repetitive stimulation (5 Hz) soleus H-reflex testing protocol and surface electromyography (EMG) were used to assess the latencies of soleus H-reflex changes in relation to tibialis anterior and soleus EMG activations of standing subjects during voluntary ankle dorsiflexions and plantar flexions at self-selected speeds. The pattern and latency of H-reflex changes in relation to EMG activity were compared between young and old subjects. RESULTS: There were no differences in the relative amount of antagonist muscle (soleus) inhibition during voluntary ankle dorsiflexions between young and old subjects (26.4% and 27.2% decrease from resting H-reflex values, respectively). Older subjects, however, required additional time to achieve these levels of inhibition. Delays in the activation of soleus H reflexes during the plantar flexion task were also observed in older subjects. Older subjects also had considerable intra- and intersubject variability in muscle temporal sequencing patterns during ankle plantar flexions. CONCLUSIONS: Although older subjects exhibited similar relative levels of alpha motoneuron inhibition and excitation during voluntary movements, this modulation was delayed when compared to younger subjects. Temporal sequencing of distal muscle activations also appears to undergo change with aging.

Adolescent↗
PubMed1996

The impact of implementing a more restrictive prescription limit on Medicaid recipients. Effects on cost, therapy, and out-of-pocket expenditures.

On November 1, 1991, the Georgia Department of Medical Assistance reduced the maximum number of monthly reimbursable prescriptions from six to five. This policy change provided a natural experiment to investigate the recipient responses to a decrease in an existing prescription limit. The research design was a quasiexperimental, retrospective, 12-month interrupted time-series analysis of a cohort. The cohort consisted of 743 ambulatory recipients who were high prescription users. Complete Medicaid claims data were obtained, in addition to pharmacy-generated computer profiles for all cohort recipients to determine Medicaid and out-of-pocket prescriptions expenditures. Interrupted time-series analyses were performed to model the effect of the five-prescription limit on total, Medicaid-reimbursed, out-of-pocket, and prescription use across eight therapeutic categories. After the implementation of the five-prescription limit, total prescription use fell 6.6%, prescriptions reimbursed by Medicaid fell 9.9%, and prescriptions paid for out-of-pocket increased 9.7%. Abrupt, permanent decreases were observed for cardiovascular, miscellaneous, pulmonary, and palliative therapeutic drug categories (alpha = 0.05), whereas gastrointestinal, chemotherapy, hormone (insulin), and central nervous system prescription use remained constant. The implementation of a more restrictive prescription limit alters prescription regimens potentially predisposing elderly Medicaid recipients to clinical consequences. Further examination of the health outcomes of these recipients is necessary.

Adult↗
PubMed1994

Effect of drug interactions on outcomes of patients receiving warfarin or theophylline.

The effect of drug interactions on costs and other outcomes for hospitalized patients receiving warfarin or theophylline was studied. Data were collected from medical records during a one-year period in two community teaching hospitals in Maryland. The data included demographic information, the duration of study-drug therapy, the number of days spent in the intensive care unit, the length of stay (LOS) in the hospital, the number of prothrombin-time tests and serum theophylline assays, and the test results. A multiple-regression procedure was used to compare outcomes of patients who were prescribed specific drugs interacting with warfarin or theophylline with those of patients who were not. Among warfarin-treated patients, there was a significant difference in each outcome measure (LOS, number of laboratory tests, and test results) between those who received an interacting drug and those who did not; mean LOS was 3.14 days longer in patients given an interacting drug. No significant differences in outcome measures were observed between the two groups of theophylline-treated patients. The cost of the increased LOS attributed to the presence of a drug interacting with warfarin was estimated to range from $779 to $1005 per hospitalization. The cost of additional prothrombin-time tests was estimated at $19-$50. Patients who received warfarin and an interacting drug had an increased LOS, required more laboratory tests, and had longer prothrombin times than patients given warfarin alone; these differences probably led to higher costs.

Adult↗
PubMed1994

Diagnosis and management of Baylisascaris procyonis infection in an infant with nonfatal meningoencephalitis.

Baylisacaris procyonis, the common raccoon ascarid, is known to cause life-threatening visceral, neural, and ocular larva migrans in mammals and birds. Two human fatalities have been previously described; however, little is known about the spectrum of human disease caused by B. procyonis. In this report, the case of a 13-month-old child who had nonfatal meningoencephalitis secondary to B. procyonis infection is presented. The suspected diagnosis was confirmed with use of newly developed enzyme immunoassay and immunoblot techniques. The diagnosis, management, and prevention of B. procyonis infection in humans is discussed. Clinical, serological, and epidemiological evaluations established B. procyonis as the etiologic agent. The child survived his infection but continued to have severe neurological sequelae. The potential for human contact and infection with B. procyonis is great. There is no effective therapy; therefore, prevention is paramount.

Animals↗
PubMed1993

Pharyngitis associated with herpes simplex virus in college students.

During a 16-month period patients who presented to the Syracuse University Health Center with upper respiratory complaints had throat swabs obtained for viral, streptococcal and Mycoplasma pneumoniae cultures. Thirty-five of 613 patients (5.7%) had herpes simplex virus (HSV) isolated. All but 2 of the HSV isolates were found to be type 1 by immunofluorescent staining. Two HSV-positive patients also grew Group A Streptococcus, one grew M. pneumoniae and three had serum heterophile antibody tests that were positive. On physical examination 25 of the 35 HSV-positive patients had pharyngeal erythema and 14 had pharyngeal exudate. Twelve of these patients had vesicular lesions of the lips, throat or gums associated with their other symptoms. For 29 of the 35 HSV-positive students the primary diagnosis assigned was pharyngitis, for 2 the diagnosis was stomatitis and the remainder were assigned a primary diagnosis of upper respiratory infection, pneumonia, bronchitis or dental infection. Thirty-two of the 35 HSV-positive patients were treated with oral antibiotics and 7 were treated with oral or topical acyclovir. During the same 16-month period 89 (6.9%) of 1297 students presenting with sore throat were culture-positive for influenza A or B, 30 (2.3%) of 1283 were culture-positive for M. pneumoniae and 169 (2.8%) of the 6016 cultured for Group A Streptococcus were positive. Serum was tested for heterophile antibody in 2438 students, and 257 (10.5%) were positive. Herpes simplex virus is associated with pharyngeal symptoms in college students, and herpes simplex pharyngitis cannot easily be distinguished clinically from other causes of acute pharyngitis in this age group.

Acute Disease↗
PubMed1993

Rhinovirus infection associated with serious illness among pediatric patients.

Rhinovirus is an important cause of respiratory infection among all age groups, but it is primarily thought of as being responsible for upper respiratory tract infection. Rhinovirus was isolated from the respiratory tract of 48 pediatric patients who were hospitalized (40) or seen in a pediatric emergency room (8) during the period of July, 1985, through December, 1988. Twenty-eight (58%) of the patients presented during the spring and early summer. Forty-one (86%) of the 48 patients were less than 12 months of age. All except four of the patients had viral cultures performed because of respiratory symptoms. Bronchiolitis was the single most frequent clinical diagnosis and was noted in equal proportion among children less than 3 months and 3 to 12 months of age. Nine patients were assigned a diagnosis of suspected sepsis. Rhinovirus infection was a complication of underlying illness for 17 (44%) of the 40 hospitalized patients, and those patients tended to be older than the otherwise healthy hospitalized infants with rhinovirus. Twenty-six patients (54%) were treated with antibacterial agents, although only one patient was documented to have a concomitant bacterial infection (Chlamydia trachomatis). Overall rhinovirus isolation during the study period represented 0.7% of all specimens submitted for viral isolation compared with 8.2% for respiratory syncytial virus. Rhinovirus infection leads to hospitalization less frequently than does respiratory syncytial virus infection, but the severity of illness and clinical presentation in young infants are similar.

Adolescent↗
PubMed1993

Upper respiratory tract infections in children.

Respiratory tract infections are a frequent problem for children, families, and pediatricians. Most such infections are trivial and do not warrant significant concern; however, for some children and some infections, aggressive and effective therapy is important. Much of the literature discussed in this article reflects attempts to clarify and improve appropriate use of antimicrobial therapy for those children in whom it is necessary.

Anti-Bacterial Agents↗
PubMed1991

Pediatrics.

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Child↗
PubMed1991

Effects of body position on crossed extension reflex in decerebrate cat: rectus femoris is more sensitive than is vastus medialis.

Physiological stimuli which increase postural extensor tone also increase excitability of the crossed extension reflex (CER). We report here that such stimuli increase excitability of the CER recorded from rectus femoris (RF) more than that of vastus medialis (VM). The difference might reflect an important role of the biarticular actions of RF, which is also a weak hip flexor, in stabilizing the hip as well as extending the knee during maintenance of posture.

Animals↗