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Biomedical subjects

T M Ball

Publications and source records attributed to T M Ball.

8 recordsLinked to original sources
PubMed1996

Missed opportunities for vaccination and the delivery of preventive care.

OBJECTIVES: To evaluate the relative impact of 2 types of missed opportunities (MOs) for vaccination, acknowledged and unacknowledged, on the immunization status of children at 2 years of age and to measure the delivery of immunizations and health care maintenance (HCM) after these types of MOs. DESIGN: Case-control study. SETTING: A large multispecialty clinic serving primarily a managed care population in Tucson, Ariz. PATIENTS: Charts of 1165 patients, ages 2 to 4 years, were reviewed for immunization status by 2 years of age. Of these patients, 652 had received all of their medical care at the clinic during their first 2 years of life. The 76 patients found to be underimmunized (UI) at 2 years of age and 76 controls, who were fully immunized (FI) by 2 years of age, frequency matched for age, were studied. MAIN OUTCOME MEASURES: The charts were reviewed for the following information: sex, age, immunizations received, HCM visits, sick visits, MOs, and pediatrician-patient interchange regarding immunization status during visits. RESULTS: Of the children who received all their care at the study site, 88% were FI. The mean number of MOs per patient occurring during the first 2 years of life was 5.8 for the UI children and 2.6 for the FI children. Only an unacknowledged MO, defined as a visit when the patient's immunization status was not reviewed, was associated with having a deficient immunization status at 2 years of age (4.6 vs 1.7, P < .001). Acknowledged MOs did not differ between UI and FI children (0.95 vs 0.76, P = .67). Immunizations were received at the subsequent visit (within a month) twice as often following a visit at which the child's deficient immunization status was acknowledged and a plan for follow-up made (P < .001). However, HCM was often not completed at the return visit. Following acknowledged MOs, patients did not return as directed 25% of the time for UI children and 5% of the time for FI children. Only 30% of FI patients completed the number of HCM visits recommended by the American Academy of Pediatrics. CONCLUSIONS: In the population studied, lack of review of the patients' immunization status was the primary cause of MOs to vaccinate. Although patients returned significantly more frequently when informed of their child's deficient immunization status, poor follow-up remained a significant problem in children who were eventually found to be lacking immunizations at 2 years of age.

Arizona↗
PubMed1993

Arm circumference v. arm circumference/head circumference ratio in the assessment of malnutrition in rural Malawian children.

The arm circumference/head circumference ratio (AC/HC) was compared with arm circumference (AC) alone in the diagnosis of protein-energy malnutrition (PEM) in 685 Malawian children between the ages of 3 and 48 months. The AC/HC ratio correlates well, r = 0.6863 (P < 0.001), with weight-for-age (WA). The sensitivity and specificity were calculated for both indicators compared to the NCHS reference standard of WA. Compared to 80 per cent WA, the 0.310 AC/HC cut-off was 92 per cent sensitive and 41 per cent specific, while the 0.290 AC/HC cut-off was 75 per cent sensitive and 74 per cent specific. AC alone in the 6-12-month-old children was 75 per cent sensitive and 89 per cent specific at a cut-off of 12.5 cm. In the children from 12 to 48 months with a cut-off of 13.5 cm the AC was 82 per cent sensitive and 70 per cent specific. The AC alone was more sensitive than AC/HC at all levels of specificity. Adding the HC to AC offered no advantage in screening for PEM in these children. In fact, if one were to use the standard 0.310 cut-off for AC/HC, the resulting low (41 per cent) specificity would identify such a large proportion of false positives as to make this ratio impractical for field use where it is most needed--in primary health care programmes with low resources which serve populations with high prevalences of PEM.

Anthropometry↗
PubMed1986

Technical grade but not recrystallized alpha-naphthylthiourea potentiates superoxide release by rat neutrophils stimulated in vitro by phorbol myristate acetate.

alpha-Naphthylthiourea (ANTU) causes pulmonary edema and pleural effusion in rats. It has been suggested that ANTU pneumotoxicity may be mediated by blood neutrophils (PMNs) via the release of reactive oxygen species. Accordingly, we tested the effect of technical grade ANTU (tANTU) on the ability of rat peritoneal PMNs to release superoxide (O2-). tANTU did not itself stimulate O2- production by PMNs, but it increased the O2- released in response to PMN stimulation by phorbol myristate acetate (PMA). This effect was dependent upon the amount of tANTU added. In PMNs activated in vitro by a submaximal PMA stimulus, addition of 20 micrograms/ml tANTU doubled superoxide release. When tANTU was recrystallized from ethanol, the purified ANTU was not effective in potentiating the effect of PMA on PMNs. This suggests that an impurity in technical grade ANTU is capable of increasing O2- release by stimulated PMNs. tANTU and recrystallized ANTU caused similar pneumotoxicity in rats in vivo, suggesting that the unidentified impurity does not markedly influence the biologic effects of ANTU.

Animals↗
PubMed1978

Visual images preserve metric spatial information: evidence from studies of image scanning.

Four experiments demonstrated that more time is required to scan further distances across visual images, even when the same amount of material falls between the initial focus point and the target. Not only did times systematically increase with distance but subjectively larger images required more time to scan than did subjectively smaller ones. Finally, when subjects were not asked to base all judgments on examination of their images, the distance between an initial focus point and a target did not affect reaction times.

Distance Perception↗
PubMed1978

Induction and repression of nitrate reductase in Neurospora crassa.

Synthesis of wild-type Neurospora crassa assimilatory nitrate reductase is induced in the presence of nitrate ions and repressed in the presence of ammonium ions. Effects of several Neurospora mutations on the regulation of this enzyme are shown: (i) the mutants, nit-1 and nit-3, involving separate lesions, lack reduced nicotinamide adenine dinucleotide (NADPH)-nitrate reductase activity and at least one of three other activities associated with the wild-type enzyme. The two mutants do not require the presence of nitrate for induction of their aberrant nitrate reductases and are constitutive for their component nitrate reductase activities in the absence of ammonium ions. (ii) An analog of the wild-type enzyme (similar to the nit-1 enzyme) is formed when wild type is grown in a medium in which molybdenum has been replaced by vanadium or tungsten; the resulting enzyme lacks NADPH-nitrate reductase activity. Unlike nit-1, wild type produced this analog only in the presence of nitrate. Contaminating nitrate does not appear to be responsible for the observed mutants' activities. Nitrate reductase is proposed to be autoregulated. (iii) Mutants (am) lacking NADPH-dependent glutamate dehydrogenase activity partially escape ammonium repression of nitrate reductase. The presence of nitrate is required for the enzyme's induction. (iv) A double mutant, nit-1 am-2, proved to be an ideal test system to study the repressive effects of nitrogen-containing metabolites on the induction of nitrate reductase activity. The double mutant does not require nitrate for induction of nitrate reductase, and synthesis of the enzyme is not repressed by the presence of high concentrations of ammonium ions. It is, however, repressed by the presence of any one of six amino acids. Nitrogen metabolites (other than ammonium) appear to be responsible for the mediation of "ammonium repression."

Amino Acids↗