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Biomedical subjects

J A Walsh

Publications and source records attributed to J A Walsh.

At least 19 recordsLinked to original sources
PubMed1997

Internal validity of the disruptive behavior disorder symptoms: implications from parent ratings for a dimensional approach to symptom validity.

A dimensional approach was used to evaluate the internal validity of the DSM-III-R ADHD-inattention, ADHD-hyperactivity/impulsivity, oppositional defiant disorder (ODD), and conduct disorder (CD) symptoms (i.e., whether a symptom has a stronger correlation with its own dimension that the other three). Parents rated 4,019 children between the ages of 2 and 19 on these symptoms. The results showed that 5 of the 6 inattention symptoms, 3 of the 4 hyperactivity symptoms, 1 of the 4 impulsivity symptoms, 6 of the 9 oppositional defiant disorder symptoms, and 8 of the 11 CD symptoms had significant internal validity. Confirmatory factor analysis (CFA) found support for inattention, hyperactivity/impulsivity, oppositional defiant, and conduct disorder dimensions. Multiple-group CFA also found support for factor pattern and loading invariance across gender. The implications of these results as well as the merits of the dimensional approach to symptom validity are discussed in the context of the DSM-IV changes in ADHD, ODD, and CD.

Adolescent↗
PubMed1997

Characterization of the growth center of the avian preovulatory follicle.

Anatomical studies have suggested that the germinal disc (GD) region (GDR; GD plus overlying granulosa cells) is the growth center of the avian preovulatory follicle. The objective of this study was to characterize the physiology of the GDR by comparing the functions of two morphologically distinct populations of granulosa cells. The three markers of the physiology of individual granulosa cells examined were 1) proliferation, 2) production of plasminogen activator (PA), and 3) production of progesterone. The effect of LH on each of these functions was also evaluated. Sections 8 mm in diameter were obtained from granulosa cells associated with the GD (GD granulosa cells) and from granulosa cells on the layer distal to the GD (nonGD granulosa cells) from the five largest preovulatory follicles (F5-F1, F1 designated the largest) 12-14 h (before the LH surge) or 2 h (after the LH surge) before ovulation. Proliferation was measured using [3H]thymidine incorporation. PA activity was measured using the chromogenic substrate S-2251. Progesterone was measured by RIA. Incorporation of [3H]thymidine was very high in GD and nonGD granulosa cells from F5 and F4 follicles and decreased dramatically as the follicle progressed through the hierarchy, but remained significantly higher in GD granulosa cells compared to nonGD granulosa cells at all stages of development examined (F5-F1). Exposure of follicles to LH in vivo inhibited [3H]thymidine incorporation by GD granulosa cells in all follicles except the F5. In contrast, in vivo exposure to LH had no effect on [3H]thymidine incorporation by nonGD granulosa cells. PA production by GD granulosa cells was high throughout the stages of maturation studied (F5-F1), whereas PA production by nonGD granulosa cells decreased as follicles matured from F5 to F1. Interestingly, LH stimulated PA production by F5 GD granulosa cells, had no effect on PA production by F3 GD granulosa cells, and inhibited PA production by F1 GD granulosa cells. In contrast, LH inhibited PA production by nonGD granulosa cells in F3 and F1 follicles. Progesterone production by GD granulosa cells was low in F3 and F1 follicles. Progesterone production by nonGD granulosa cells increased as the follicle matured from the F3 to F1 stage and was stimulated significantly by LH. These data indicate that physiological differences in granulosa cell function are dependent upon the location of granulosa cells relative to the GD. GD granulosa cells are less mature, proliferate more rapidly, and produce more PA than nonGD granulosa cells, which produce more progesterone and less PA. Differences in granulosa cell function may be due to the influence of the GD, providing physiological evidence that the GDR may be the growth center of the follicle.

Animals↗
PubMed1997

Internal validity of attention deficit hyperactivity disorder, oppositional defiant disorder, and overt conduct disorder symptoms in young children: implications from teacher ratings for a dimensional approach to symptom validity.

Uses a dimensional approach to evaluate the internal validity of the attention deficit hyperactivity disorder (ADHD) inattention (I) and hyperactivity/impulsivity (H/I), oppositional defiant disorder (ODD), and overt conduct disorder (CD) symptoms (i.e., whether a symptom has a stronger correlation with its own dimension than the other three dimensions). In Study 1, teachers rated 1,445 children on the DSM-III-R I, H/I, ODD, and overt CD symptoms. In Study 2, teachers rated 1,711 children on the DSM-IV I, H/I, ODD, and overt CD symptoms. All the I symptoms showed internal validity in both studies. In contrast, the H/I symptoms and the ODD symptoms, especially the H/I symptoms, showed weaker internal validity. All the overt CD symptoms showed internal validity except the DSM-IV bullies others symptom, with this symptom being more strongly related to the ODD dimension. Confirmatory factor analysis provided support for a 4-factor model consisting of I, H/I, ODD, and overt CD factors. Finally, the importance of internal validity for the construct validation of the disruptive behavior symptoms is discussed.

Adolescent↗
PubMed1995

Setting priorities for the Children's Vaccine Initiative: a cost-effectiveness approach.

To help the Children's Vaccine Initiative (CVI) achieve its goal of new and improved children's vaccines, we developed and applied a cost-effectiveness model to set priorities for vaccine development. The model measures the health benefits in additional Quality-Adjusted Life Years (QALYs) gained by the combined birth cohorts of all developing countries over an assumed useful life of a proposed vaccine (generally 10 years). It measures costs as the net cost of developing, procuring, and administering the vaccine to the same population and time frame compared to the status quo (the current vaccine, if any). It weights each dollar of in-kind allocation of the existing health infrastructure less heavily than a dollar cash outlay to purchase new vaccine to reflect severe constraints on foreign exchange and non-personnel costs. It expresses cost-effectiveness as the net cost per QALY. The model was applied to 13 candidate vaccines selected by the CVI for initial analysis on the basis of their near-term feasibility. The five most cost-effective improvements, each of which could generate a QALY inexpensively (below $25 per QALY), were an early-administration or an early two-dose measles vaccine, slow release tetanus toxoid (for women), improved typhoid vaccine, and hepatitis B combined with diphtheria-tetanus-pertussis vaccine.

Child, Preschool↗
PubMed1994

Colour duplex ultrasound: a screening modality for femoropopliteal disease in patients with intermittent claudication.

In patients presenting with intermittent claudication, Colour Duplex Ultrasound (CDU) examination of the femoro-popliteal segment has been proposed as a screening modality. Those patients with atheromatous lesions suitable for percutaneous transluminal angioplasty (PTA) could proceed to diagnostic angiography. Patients with long segment occlusive disease demonstrated by CDU, who were not considered suitable candidates for surgery, would not require angiographic examination. This prospective study was performed on 46 limbs in 25 consecutive patients who presented for investigation of claudication. There was close correlation between the two methods in the demonstration of high-grade stenoses and occluded segments. Using angiography as the 'gold standard' this study indicated a diagnostic accuracy for CDU of 93% with a sensitivity of 89% and a specificity of 95%. Angiography tended to show longer occluded segments than CDU. Colour Duplex Ultrasound shows promise as a screening investigation in patients with intermittent claudication to detect lesions that may be suitable for PTA.

Aged↗
PubMed1992

A retrospective analysis of infra-inguinal arterial reconstruction: three year patency rates.

Primary infra-inguinal arterial reconstructions were reviewed for primary patency and outcome of thrombosis in 144 patients. Distal anastomoses in these patients were to the popliteal artery and were above the knee in 63, below the knee in 53 and at the tibial level in 28. The treatment used was: polytetrafluoroethylene (PTFE) in 33 cases, PTFE with an interposition vein cuff in 29 cases, autogenous saphenous vein (ASV) in situ in 47 cases, and reversed technique in 26 cases. Life table analysis showed a 59% overall primary patency at 3 years. Patency rates of above knee anastomoses (65%) and below knee (61%) were statistically different from the tibial anastomoses (42%, P = 0.005). In both above and below knee popliteal anastomoses there was a statistically significant difference in the patency of ASV and the PTFE/vein cuff technique (P = 0.0006) but there was no difference between ASV and PTFE. There was no difference in patency rates for the various types of grafts with tibial anastomoses. Data were analysed at 3 years, taking into account the variables of smoking, diabetes or indications for surgery respectively and no difference was found in patency. The number and calibre of the run-off vessels did not influence patency significantly, hence anastomosis to any good quality vessel regardless of run-off is recommended. The poor results with the interposition vein cuff technique are unexplained but this study suggests that the technique should be reserved for anastomoses below the popliteal artery.

Adult↗
PubMed1991

Evaluation of efficacy and safety of an inactivated virus vaccine against feline leukemia virus infection.

An inactivated virus vaccine was developed for prevention of FeLV infection in domestic cats. When given in 2 doses, 3 weeks apart, to cats that were greater than or equal to 9 weeks old at the time of first vaccination, the vaccine prevented persistent viremia from developing in 132 of 144 (92%) vaccinates after oronasal challenge exposure with virulent FeLV. In contrast, persistent viremia developed after oronasal challenge exposure with FeLV in 39 of 45 (87%) age-matched nonvaccinated control cats. Transient viremia, indicated by early detection of p27 by ELISA in serum of cats protected from persistent viremia at 12 weeks after challenge exposure, was found in 10 of 132 (8%) vaccinates. Cats that were aviremic 12 to 16 weeks after challenge exposure were examined for reactivation of latent FeLV infection; 4 weekly doses of methylprednisolone were administered, followed by in vitro culture of bone marrow cells. Latent infection was readily reactivated in 6 of 8 (75%) nonvaccinated control cats that had been transiently viremic after challenge exposure. However, latent infection was reactivated in only 5 of 48 (10%) protected vaccinates, and in none of 38 vaccinates in which transient viremia had not been detected. In a safety field trial, only 34 mild reactions of short duration were observed after administration of 2,379 doses of vaccine to cats of various ages, breeds, and vaccination history, for a 1.43% reaction rate. Results indicate that the aforementioned inactivated virus vaccine is safe and efficacious for the prevention of infection with FeLV.

Animals↗
PubMed1991

Dermatoglyphics and acute lymphocytic leukemia in children.

Cellular features of acute lymphocytic leukemia (ALL) in children suggest that it originates in abnormal embryogenesis. Because palmar flexion creases develop in the embryo at the same time as the blood-forming cells, and because both arise from mesodermal tissue, insults to the embryo that may lead to leukemic changes in the blood-forming cells may also result in aberrant palmar crease patterns. This study investigated the relationship between aberrant palmar creases and ALL in children who developed leukemia at age 6 years or younger. Odds ratios and chi squares demonstrated significant differences in bilateral aberrant palmar creases between ALL children and relatives (P less than .025). Differences were not explained by familial clustering of aberrant creases. These results support the theory that the insult occurred during pregnancy, probably in the first trimester. There were no significant differences in either bilateral or unilateral aberrant palmar creases between ALL children and their siblings. All children with bilateral aberrant creases had a higher incidence of central nervous system involvement (50%) than those without bilateral aberrant creases (6%). This may reflect a preleukemic change in utero before the time the blood-brain barrier has been established.

California↗
PubMed1990

Vascular outflow resistance and angiographic assessment of lower limb arterial reconstructive procedures.

In an attempt to predict early graft occlusion secondary to poor distal run-off, the outflow resistance was measured intra-operatively and compared with the intra-operative angiogram in 50 patients undergoing lower limb bypass procedures. With arterial inflow occluded, 60 mL of plasmalyte was infused via a catheter and the resultant pressure generated in the graft was measured through a second catheter connected to a pressure transducer and recorder. Using the infusion rate and integrated pressure value, outflow resistance was calculated. High resistance measurements were defined as grafts with outflow resistance greater than 1.1 mmHg/mL per min, low measurements were defined as values less than 0.5 mmHg/mL per min and intermediate measurements were those in the range 0.5-1.1 mmHg/mL per min. Angiograms were classified independently of resistance measurements by scoring the numbers of run-off vessels crossing the ankle and stenoses, with subsequent assignment of the patient to one of three groups with either low, intermediate, or high probability of graft failure. Early graft failure was defined as cessation of graft function within 3 months of surgery. Early graft failure occurred in both cases with high outflow resistance and in seven of 44 with low outflow resistance. Of these nine occluded bypasses, six had been placed in the high probability of occlusion category on angiographic appearance and three in the intermediate category. Assessment of angiographic appearance and prediction of patency on a prospective basis had a sensitivity rate of 67% and a specificity rate of 78%. The corresponding sensitivity and specificity rates with resistance measurements were 22% and 100%, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗
PubMed1988

Selectivity within primary health care.

While great strides have been made in improving socioeconomic conditions in the developing world, prospects for health for all remain remote. Resources are few, and difficult decisions must be made concerning the priorities for their use. This paper addresses several topics involved in making these choices including the methods for determining priorities and ensuring effectiveness of resource use. First, prioritizing. Information is needed concerning the prevalence, mortality, morbidity, feasibility and cost of control for each disease of importance in the area under consideration. Second, the use of technology. In discussion of health care some have denigrated the concentration many programs have placed on specific methods and technologies. Nevertheless, technological advances, while some have had detrimental results, have often led to improved living conditions; for example, improved seed and fertilizer use, improved water pumps, family planning efforts. These technologies required a larger investment in management, financial and communication systems. Health interventions are frequently more various and complex than these and need a similar support system for impact. However there are many shortcomings in health services; the paper looks at some of these learnt through experience, and concludes that the lack of impact on health of large scale health programs that have provided selective interventions is probably related to an inadequate recognition of the importance of community and political involvement and of the necessary social, cultural, financial, management and administrative underpinnings.

Developing Countries↗
PubMed1988

Inter-relationships between vascular thromboxane and prostacyclin synthesis.

We have measured the effect of various concentrations of arachidonic acid on the rates of synthesis of prostacyclin and thromboxane in human umbilical artery slices. Increasing concentrations of arachidonate increased the rate of thromboxane synthesis, but had no effect on the rate of prostacyclin synthesis. However, in dexamethasone-treated artery slices, arachidonate increased the rate of thromboxane and prostacyclin synthesis. Overall, it was demonstrated that arachidonate can alter the ratio of prostacyclin/thromboxane synthesis in untreated artery slices and, by inference, arachidonate can alter the thrombogenicity of vascular endothelium. A mechanism is proposed to explain the arachidonate-induced changes in the prostacyclin/thromboxane ratio.

Arachidonic Acid↗
PubMed1987

Effect of 50 mg enteric-coated aspirin (Astrix) on thromboxane and prostacyclin synthesis.

Although low-dose soluble aspirin can be recommended as a useful anti-thrombotic drug regimen in patients with vascular disease, enteric-coated preparations have a theoretical advantage for aspirin preparations which are to be ingested daily for many years. We have demonstrated that a 50 mg enteric-coated aspirin formulation (Astrix) which has an absorption rate much lower than soluble aspirin, is sufficient to inhibit platelet thromboxane synthesis while causing no major decrease in vascular prostacyclin synthesis.

Aspirin↗
PubMed1987

Transluminal balloon angioplasty in diabetic peripheral vascular disease.

Transluminal (balloon) angioplasty of iliac or superficial femoral stenoses in 18 diabetic patients resulted in a significant improvement in ankle/brachial systolic pressure index with marked symptomatic improvement in 16, little change in one and deterioration requiring arterial bypass surgery in one patient. Follow-up for 12 months or more showed that the initial good results were sustained despite a downward drift in ankle pressures. These findings indicate that transluminal angioplasty has a useful place in the management of proximal atherosclerotic stenotic lesions in diabetic patients with symptomatic peripheral vascular disease.

Aged↗