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Biomedical subjects

T Greene

Publications and source records attributed to T Greene.

At least 73 records · Page 4Linked to original sources
PubMed1993

Dentine lead and intelligence prior to school entry: a statistical sensitivity analysis.

The relationship between circumpulpal dentine lead and IQ at age 4 years 10 months was examined in 164 urban children. Negative correlations were observed between dentine lead and IQ scores, but were reduced in magnitude after adjustment for social covariates. Analyses using errors-in-variables regression models indicated that the degree of this reduction depended on difficult-to-verify assumptions regarding the magnitudes of (i) measurement error in the lead variable and the covariates, and (ii) possible changes in the caretaking environment resulting from conjectured effect of lead on the child's cognitive and behavioral development. Sensitivity analyses were conducted in which estimates of the lead effect were repeatedly computed and compared for a range of possible values for factors (i) and (ii). It was found that the statistical significance of the lead effect on Full Scale IQ depended on the relative magnitudes of these factors, and that failure to incorporate measurement error in the analysis would have led to gross overestimation of the precision of the findings.

Bias↗
PubMed1993

Glomerular filtration rate measurements in clinical trials. Modification of Diet in Renal Disease Study Group and the Diabetes Control and Complications Trial Research Group.

To assess the utility and precision of GFR measurements in multicenter trials, the test performance and variability of GFR were analyzed in 2,250 patients enrolled in 44 clinical centers participating in either the Modification of Diet in Renal Disease (MDRD) Study or the Diabetes Control and Complications Trial (DCCT). GRF was measured as the renal clearance of [125I]iothalamate after an sc injection without epinephrine. The studies used similar protocols for obtaining blood and urine, training clinical center staff, and processing specimens in central laboratories. The performance of GFR measurements, assessed from adherence to protocol and quality control analyses, was excellent. The variability among the four clearance periods (intratest coefficient of variation [CV]) was acceptable; the median intratest CV for GFR was 9.4% in the MDRD Study and 11.7% in the DCCT. The pattern of decline in serum counts was better approximated by an exponential rather than a linear relationship. The cause of the intratest variability in GFR measurements was explored by univariate and multivariate analysis. The intratest CV was highest at the extremes of GFR. Among patients with a high GFR (> 90 mL/min per 1.73 m2), most of whom were participants in the DCCT, the higher intratest GFR was due, in part, to a systematic decline in GFR during the test. Among patients with a very low GFR (< 13 mL/min per 1.73 m2), technical difficulties in urine collections contributed substantially to the higher intratest CV. Other patient characteristics, including age, gender, weight, serum glucose, renal diagnosis, and use of diuretics, were not strongly correlated with the intratest CV. The precision of GFR measurements was assessed from the variability from measurement to measurement (interest CV). Among MDRD Study subjects, in whom two measurements of GFR were performed over a 3-month interval, the median interest CV was relatively low (6.3%) and was only weakly related to the intratest CV. Thus, GFR measurements are reasonably precise, even if the intratest CV is high. Given the relatively high intratest CV that is characteristic of GFR measurements, the estimate of GFR in an individual is more precise if multiple clearance periods, rather than a single period, are included. Similarly, the estimate of mean GFR for a population is also more precise if multiple clearance periods are included. In conclusion, by the use of standardized methods, an acceptable precision of GFR results can be obtained in multicenter trials. The same methods can be applied in clinical practice.(ABSTRACT TRUNCATED AT 400 WORDS)

Adolescent↗
PubMed1993

Baseline characteristics in the Modification of Diet in Renal Disease Study.

The Modification of Diet in Renal Disease Study is randomized, multicenter, clinical trial designed to determine the effects of three levels of dietary control of protein and phosphorus and two levels of blood pressure control on the rate of decline of kidney function among persons with chronic renal disease. Study participants were assigned to one of two studies, Study A or Study B, depending on their GFR just before randomization. Within each study, participants were randomly allocated to one of two levels of blood pressure control and to one of two dietary interventions according to separate 2 x 2 factorial designs. A total of 840 men and women aged 18 to 70 were randomized. This report summarizes the demographic, biochemical, and clinical characteristics of the randomized participants at the time of entry into the trail, overviews the protocol and purposes of the baseline period before randomization, and evaluates the balance among the treatment intervention groups within Studies A and B at the time of randomization. Major indicators of renal function were found to be well balanced among the treatment groups. Selected baseline characteristics of participants in the Modification of Diet in Renal Disease Study are compared with those of other renal clinical trials and with those of new cases of treated ESRD reported in the United States Renal Data System.

Adolescent↗
PubMed1992

Low-dose (7.5 mg) oral methotrexate for chronic progressive multiple sclerosis. Design of a randomized, placebo-controlled trial with sample size benefits from a composite outcome variable including preliminary data on toxicity.

OBJECTIVE: To present a detailed description of (1) the study design of this ongoing trial, (2) advantages of using a composite outcome variable instead of multiple individual outcome measures, (3) treatment group characteristics at baseline, and (4) observed short-term methotrexate (MTX) toxicity. DESIGN: Randomized, double-masked, placebo-controlled intervention study. SETTING: Referral-based outpatient multidisciplinary multiple sclerosis (MS) clinic. PATIENTS: Participation offered to all clinically definite chronic progressive multiple sclerosis (CPMS) patients attending clinic ages 21 to 60, disease duration > 1 year, Expanded Disability Status Scale (EDSS) score 3.0 to 6.5 (ambulatory with moderate disability). Patients first stratified by EDSS 3.0 to 5.5 and 6.0 to 6.5, then randomized to MTX or placebo treatment. INTERVENTION: Weekly oral low-dose (7.5 mg) MTX or identical-appearing placebo for 2 years followed by a 1-year observation period. MAIN OUTCOME MEASURES: Sample size calculations undertaken prior to enrolling patients based upon a composite outcome variable consisting of designated change in any of the following functional measures: (1) EDSS, (2) Ambulation Index (AI), (3) Box and Block Test (BBT), and (4) 9-Hole Peg Test (9HPT). RESULTS: (1) Treatment group characteristics were comparable at baseline, (2) no patient has been withdrawn for adverse effects or lost to follow-up, (3) no significant short-term MTX toxicity has been observed. CONCLUSIONS: (1) The use of a composite outcome measure in the design of MS clinical trials is a promising alternative to multiple individual outcome measures that are relatively insensitive to detecting clinical change, (2) low-dose oral weekly MTX does not appear to be associated with significant short-term toxicity in CPMS. Conclusions regarding therapeutic efficacy of MTX in MS must await completion of this clinical trial.

Adult↗
PubMed1992

Contributions of risk factors to elevated blood and dentine lead levels in preschool children.

The relationship between blood lead level (PbB) and an array of socio-demographic, behavioral, caregiving and environmental risk factors was investigated in a cohort of socioeconomically disadvantaged urban children at ages 2, 3 and 4 years and 10 months. The risk factors were also related to dentine lead level (PbD) from shed deciduous teeth. Strong persistent pairwise relationships with PbB and PbD were observed for maternal IQ, parental education, examiner ratings of the condition and cleanliness of the physical environment, and the HOME scale, which assesses the quality of the caretaking environment. The association between dirt pica and PbB was strong at 2 years (r = 0.30), but was less pronounced in subsequent assessments as the prevalence of pica decreased. Insignificant or weak relationships were found for maternal assessments of paint-and-plaster peeling in the home and non-dirt pica. The HOME scale and the ratings of the condition of the physical environment were significantly related to PbB and PbD even after adjustment for socio-demographic factors. These two measures were also strongly related to an array of developmental outcomes. The results indicate that statistical adjustment specifically for the quality of the caretaking environment can lead to substantial reductions in estimates of adverse lead effects.

Adult↗
PubMed1992

Postpartum changes in maternal blood lead concentrations.

Studies of lead concentrations in blood during pregnancy are of interest because of the possibility of adverse effects on the fetus. One report of a single case suggested that blood lead concentrations are raised during pregnancy. This is consistent with the hypothesis of a pregnancy induced mobilisation of lead from bone. Data presented herein, however, indicate that blood lead measures are appreciably lower at delivery than they are at six months post partum. Other factors including but not limited to transmission to the fetus, may be influencing lead concentrations during pregnancy.

Adult↗
PubMed1991

Prenatal alcohol exposure and preschool physical growth: a longitudinal analysis.

This report examines the effects of fetal alcohol exposure on size and growth in an urban cohort followed prospectively through early childhood. Indices of prenatal drinking were related to measurements of weight, stature (length), and head circumference obtained at birth and during five subsequent in-home assessments. Small but statistically significant relationships were detected between short-term recall estimates of drinking during pregnancy and weight and length at birth. The strength of these relationships diminished during the preschool assessments. However, estimates of catch-up growth associated with alcohol exposure were not statistically significant. With the exception of a single case with a profile of signs characteristic of fetal alcohol syndrome, an adverse effect of prenatal alcohol exposure on head circumference was not indicated.

Alcohol Drinking↗
PubMed1991

Adjustment for cofactors in pediatric research.

Behavioral and developmental pediatric research often seeks to form causal inferences from associations between variables obtained in nonrandomized studies. To do this it is necessary to distinguish the effects of the independent variable of interest from other factors with which it is correlated. We review statistical adjustment procedures for assessing the effects of the independent variable after controlling for other variables, called cofactors. We present guidelines for cofactor adjustment for different patterns of causal relationships occurring in the developmental pediatric literature. We also review procedures for selecting a subset of cofactors from a larger array of candidate variables. Finally, we examine common methodological complications related to cofactor adjustment, including the presence of measurement error in the independent variable and/or the cofactors.

Child↗
PubMed1990

Prenatal alcohol exposure and language development.

The effects of fetal alcohol exposure on language and speech acquisition were investigated in a cohort of socioeconomically disadvantaged urban children. Language development was assessed by instruments derived from the Expressive and Receptive Scales of the Sequenced Inventory of Communication Development (SICD) at 1, 2, and 3 years, and by indices constructed from a taped speech sample at age 2 years. Three indices of maternal drinking were supplemented with birth weight and a tally of craniofacial anomalies as early indicators of fetal alcohol damage. No statistically significant relationships were found between the alcohol and language indices after statistical control for confounding variables. The anomalies tally was marginally related to reduced language scores. The statistical significance of this relationship, depended, however, on a single child with the characteristics of fetal alcohol syndrome. The pattern of results suggested that the anomalies tally, and to a lesser extent birth weight, are more sensitive indicators of fetal alcohol exposure than subsequent language development.

Child, Preschool↗
PubMed1989

An alpha-N-acetylgalactosaminylation at the threonine residue of a defined peptide sequence creates the oncofetal peptide epitope in human fibronectin.

The monoclonal antibody FDC-6 defines a structure specific to oncofetal fibronectins (onf-FN) isolated from fetal and malignant cells and tissues. The absence of this structure is characteristic of normal fibronectin (nor-FN) isolated from plasma and adult normal tissue (Matsuura, H., and Hakomori, S. (1985) Proc. Natl. Acad. Sci. U. S. A. 82, 6517-6521). The minimum structure required for FDC-6 reactivity was determined to be Val-Thr-His-Pro-Gly-Tyr (VTHPGY) with alpha-N-acetylgalactosamine (alpha-GalNAc) at Thr, although alpha-GalNAc per se is not involved in the FDC-6 epitope (Matsuura, H., Takio, K., Titani, K., Greene, T., Levery, S. B., Salyan, M. E. K., and Hakomori, S. (1988) J. Biol. Chem. 263, 3314-3322). Thus, a single glycosylation on the normally occurring peptide of FN may induce conformational changes in the peptide to form the specific oncofetal epitope recognized by FDC-6 antibody. The FDC-6-nonreactive synthetic peptide containing the VTHPGY sequence was converted into FDC-6-reactive form on incubation with alpha-N-acetylgalactosaminyltransferase and UDP-[3H]GalNAc in the homogenate of hepatoma cell HUH-7, human fetal fibroblast cell line WI-38, or human epidermoid carcinoma cell line A431. Such a conversion did not take place when the same enzyme fraction of normal adult tissue was incubated with the VTHPGY peptide under the same conditions. Thus, the occurrence of alpha-GalNAc transferase recognizing the VTHPGY peptide sequence (UDP-GalNAc:VTHPGY alpha-GalNAc transferase) is specific for fetal and cancer tissues, and absent in normal adult tissues. However, a similar alpha-GalNAc transferase activity capable of transferring the GalNAc residue to other Ser or Thr hydroxyl groups of nor-FN, and presumably located at the type III connecting segment region, was detectable in homogenate of various normal tissues. Such enzyme activity was determined with the use of enzymatically de-O-glycosylated nor-FN. Thus, the enzymatic basis of FDC-6 epitope formation is a subtle change in the substrate specificity of alpha-GalNAc transferase. The normal enzyme is incapable of transferring alpha-GalNAc from UDP-GalNAc to the Thr residue of the VTHPGY sequence, but is capable of transferring alpha-GalNAc to other Ser or Thr residues of FN. In contrast, alpha-GalNAc transferase of fetal and cancer tissues may have broader specificity and the capability to transfer GalNAc to Thr or Ser residues, including those of the VTHPGY sequence.

Amino Acid Sequence↗
PubMed1988

The oncofetal structure of human fibronectin defined by monoclonal antibody FDC-6. Unique structural requirement for the antigenic specificity provided by a glycosylhexapeptide.

Previously, monoclonal antibody FDC-6 was established, which defines a structure specific for fibronectins isolated from fetal and malignant cells and tissues. The presence of the FDC-6-defined structure at type III connecting segment (III CS) is characteristic of oncofetal fibronectin (onf-FN), and its absence is characteristic of normal fibronectin (nor-FN) (Matsuura, H., and Hakomori, S. (1985) Proc. Natl. Acad. Sci. U. S. A. 82, 6517-6521). Hepatoma fibronectin was sequentially digested by various proteases, followed by subsequent chromatography on an FDC-6 affinity column and reverse-phase columns at each step of digestion. A single strongly active glycosylhexapeptide (glycopeptide 1) and an inactive glycosylpentapeptide (glycopeptide 3) were isolated from glycopeptide A containing 35 amino acid residues. The minimum essential structure required for the FDC-6 activity was found to be a hexapeptide sequence Val-Thr-His-Pro-Gly-Tyr having NeuAc alpha 2----3Gal beta 1----3GalNAc or its core (Gal beta 1----3GalNAc or GalNAc) linked at threonine. Various synthetic peptides including the Val-Thr-His-Pro-Gly-Tyr sequence and a glycopeptide having the Val-Thr-His-Pro-Gly pentapeptide with the same glycosylation at threonine were all inactive. Elimination of sialic acid slightly increased the activity, and subsequent elimination of galactose did not alter the activity; however, removal of the Gal beta 1----3GalNAc residue by endo-alpha-N-acetylgalactosaminidase from desialylated glycopeptide A resulted in total inactivation of the reactivity with FDC-6 antibody. Thus, a single glycosylation at a defined threonine residue of the III CS region may induce conformational changes in the peptide to form the specific oncofetal epitope recognized by FDC-6 antibody. This finding opens the possibility that a number of other oncofetal epitopes consist of a peptide and a common O-linked carbohydrate and that the combination produces a conformation specific to cancer or to a stage of development.

Amino Acid Sequence↗
PubMed1988

Digital subtraction wrist arthrography: use of double contrast technique as a supplement to single contrast arthrography.

A new technique using double contrast after digital subtraction wrist arthrography is presented. Results of the double contrast wrist arthrograms were essential to the diagnosis, confirmed the diagnosis, or salvaged an otherwise poor or nondiagnostic examination. It was found that intra-articular injection of air augments the information obtained during postarthrogram active motion studies under fluoroscopy. Double contrast wrist arthrography has proved valuable when the standard contrast arthrogram fails to yield diagnostic information.

Arthrography↗
PubMed1985

Intraperitoneal recombinant alpha 2-interferon for 'salvage' immunotherapy in persistent epithelial ovarian cancer.

Fourteen patients with epithelial ovarian cancer were treated with intraperitoneal (i.p.) administration of alpha-recombinant interferon (rIFN-alpha 2) after documentation of persistent disease at second-look laparotomy and combination chemotherapy. After therapy, 11 patients had a surgical re-evaluation which confirmed 4 complete responses (36%), 1 partial response (9%), and disease progression in 6 (55%). Five of 7 patients (71%) with minimal residual disease (MRD, i.e. less than 5 mm) had a surgically-documented response, whereas there was none in the 4 patients whose tumors were greater than or equal to 5 mm. Fever greater than or equal to 38 degrees C was seen in 58%, greater than or equal to 39.0 degrees C in 18%; nausea and vomiting in 37%, and abdominal pain in 22%. There was no consistent alteration in peripheral WBC's during treatment, while i.p. monocytes and lymphocytes showed a significant boost on day 1 after each dose of rIFN-alpha 2. Natural killer (NK) lymphocyte cytotoxicity was elevated in the i.p. cavity fluid obtained from most patients on day 1 after treatment, while blood NK values showed considerable variability. Pharmacokinetic studies showed i.p. levels of rIFN-alpha 2 were 30-1000 times blood levels. I.p. rIFN-alpha 2 may act by increasing concentrations of drug and augmenting regional host cells in patients with MRD ovarian cancer.

Adult↗
PubMed1985

Intraperitoneal recombinant alpha-interferon for "salvage" immunotherapy in stage III epithelial ovarian cancer: a Gynecologic Oncology Group Study.

Fourteen patients with persistent epithelial ovarian cancer documented at second look laparotomy after combination chemotherapy were treated with 146 cycles of alpha-recombinant interferon (rIFN-alpha 2) administered i.p. The initial dose was 5 X 10(6) units which was escalated weekly to 50 X 10(6) units over 4 weeks and then continued weekly for a total of 16 weeks. Eleven patients underwent surgical reevaluation after therapy which confirmed four pathological complete responses (36%), one partial response (9%), and disease progression in six patients (55%). Five of seven patients (71%) with residual tumor less than 5 mm had a surgically documented response, whereas there was no response in the four patients whose tumors were greater than or equal to 5 mm. Three patients were evaluable for clinical response only: one patient who refused surgery had a complete clinical response with total resolution of ascites; one had stable disease; and one had disease progression. Fever greater than or equal to 38 degrees C was seen in 58%, fever greater than or equal to 39.0 degrees C was seen in 18%, vomiting in 37%, abdominal pain was reported in 22%, and one patient had infectious peritonitis. Peripheral white blood cell counts and i.p. washings were obtained pretreatment and on days 1, 3, and 7 after treatment. While there was no consistent alteration in peripheral white blood cell counts, the numbers of i.p. monocytes and lymphocytes showed a significant boost on day 1 after each dose of rIFN-alpha 2. Natural killer lymphocyte cytotoxicity was elevated in the i.p. cavity fluid obtained from most patients on day 1 after treatment, while blood natural killer lymphocyte cytotoxicity values showed considerable variability. Pharmacokinetic studies show that i.p. levels of rIFN-alpha 2 were 30-1000 times blood levels. rIFN-alpha 2 i.p. may act by increasing concentrations of drug and augmenting regional host cells in patients with minimal residual ovarian cancer.

Adult↗