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Biomedical subjects

J Tanner

Publications and source records attributed to J Tanner.

At least 37 records · Page 2Linked to original sources
PubMed1998

The effects of hippocampal aspiration lesions on conditioning to the CS and to a background stimulus in trace conditioned suppression.

Rats with hippocampal aspiration lesions or cortical control lesions were compared to sham operated controls in a trace conditioned suppression task, in which a long-lasting background stimulus played the role of more conventional contextual cues. In all three surgical treatment groups, conditioning to the explicit conditioned stimulus (CS) decreased, but conditioning to the background cue increased, when a longer trace interval was used. There was thus no evidence of a differential partitioning of associative conditioning as a result of the lesion, despite the evident sensitivity of the behavioural paradigm to variations in the CS-->unconditioned stimulus (US) interval. This result contrasts with earlier reports using conventional contextual cues in analogous experimental designs, and so suggests that the sensitivity of contextual conditioning to hippocampal dysfunction depends at least in part on the physical nature of conventional contextual cues, and not solely on the less precise predictive information that such cues typically provide.

Animals↗
PubMed1997

Tanner-Whitehouse bone age reference values for North American children.

On the basis of 1090 x-ray films from 225 boys and 225 girls ages 8 to 16 years-participants in the Project Heartbeat longitudinal study who were living in a generally above-average income environment near Houston, Tex.-we provide Tanner-Whitehouse Mark 2 RUS (radius, ulna, and selected metacarpals and phalanges) bone age reference values for North American children of European origin. We designate these values as US90 (for the 1990s) reference values, in contrast to the original British bone age standards, called UK60 (for the 1960s). The US90 children matured considerably earlier than those on which the UK60 standards were based, though only about 3 months earlier than contemporary Spanish children. A study of 190 x-ray films from a research longitudinal series of 23 healthy boys in Virginia yielded values very close to the Houston values, confirming that our US90 reference values should be used in North America, pending a more extensive survey.

Adolescent↗
PubMed1997

Patterns of compliance with once versus twice daily antihypertensive drug therapy in primary care: a randomized clinical trial using electronic monitoring.

OBJECTIVE: To evaluate patterns of compliance with once versus twice daily administration of antihypertensive therapy (primary-outcome measure) and relevance of partial compliance for blood pressure control (secondary outcome measure). DESIGN: Multicentre, nonblinded, parallel group randomized design. SETTING: Nonacademic primary care practices across Canada. STUDY POPULATION: Patients with mild essential hypertension (diastolic blood pressure 95 to 110 mmHg) of either sex (40% women), age 18 to 80 years (average 55 years). One hundred and ninety-eight patients were randomized to active treatment; 14 patients discontinued the study because of side effects. INTERVENTIONS: After a four-week placebo run-in period, patients were randomized to amlodipine 5 mg once-a-day or diltiazem slow release formulation (SR) 90 mg twice daily. Doses were increased to 10 mg and 180 mg to achieve sitting diastolic blood pressure of 90 mmHg or less. OUTCOME MEASURE: During 20 weeks on active treatment, compliance was assessed by pill counts and medication event monitoring system (MEMS), assessing percentage of prescribed doses taken, percentage days correct doses taken, percentage prescribed doses taken on time and blood pressure control as determined by office blood pressure measurement. RESULTS: The percentage prescribed doses taken (by either pill count of MEMS) showed a high degree of compliance, similar for the two treatments. However, other parameters of compliance were significantly better with once versus twice daily therapy. Partial compliance (less than 80% by pill count) led to less blood pressure control with the short acting diltiazem, but did not affect blood pressure control for the long acting amlodipine. Side effects profiles did not differ between the two treatments. CONCLUSIONS: Within the constraints of a clinical trial, hypertensive patients in primary care show a high degree of overall compliance with once or twice daily pill-taking, but patterns of pill-taking are more erratic with twice versus once daily medication, particularly in men. The results suggest that the negative consequences of partial compliance for blood pressure control can be offset by choosing agents with a duration of action well beyond the dosing interval.

Adolescent↗
PubMed1996

Epstein-Barr virus transmission from a blood donor to an organ transplant recipient with recovery of the same virus strain from the recipient's blood and oropharynx.

A previous study (Savoie et al, Blood 83:2715, 1994) identified eight transplant patients who acquired Epstein-Barr virus (EBV) infection during the peritransplant period. Three of these patients subsequently developed B-cell lymphoproliferative disease within 4 months of transplantation. Among these, there was a 16-year-old liver transplant patient who was negative for EBV at the time of transplant and who received an EBV-negative organ. After transplant, this patient was transfused with 9 U of packed red blood cells. Eight of the donors were EBV-positive and one was EBV-negative. We succeeded in obtaining spontaneous lymphoblastoid cell lines (LCLs) from the blood of three of these donors, one of whom also yielded a cord-blood line established with his throat-wash EBV. Blood from a fourth donor did not yield an LCL, but his throat washing did have transforming activity when inoculated onto cord-blood leukocytes. We initially could establish spontaneous LCLs only from the recipient's blood. However, a throat-wash sample taken 11 weeks later did show transforming activity. The recipient was shown to have acquired the EBV infection from one of eight EBV-seropositive blood donors. Analysis of fragment length polymorphisms after polymerase chain reaction amplification of the EBV BamHI-K fragment was used to establish strain identity. Western blot analysis for existence of size polymorphisms in three classes of Epstein-Barr nuclear antigens (EBNA-1, EBNA-2, and EBNA-3) confirmed the DNA results. It is noteworthy that the blood donor responsible for transmitting his EBV strain to the recipient had experienced clinical infectious mononucleosis 15 months before donating blood. Our results may, thus, indicate a requirement for leukodepletion of blood destined for immunosuppressed EBV-negative patients. Finally, blood donors with a recent history of infectious mononucleosis should probably be identified so that their blood is not given to EBV-negative transplant patients.

Adolescent↗
PubMed1996

Persistence of anti-hypertensive effect after 'missed doses' of calcium antagonist with long (amlodipine) vs short (diltiazem) elimination half-life.

1. Calcium antagonists with long vs short elimination half-life may show marked differences in their antihypertensive effect during short interruptions of therapy by missed doses. 2. In the present study we evaluated the blood pressure lowering effect of amlodipine vs diltiazem both on active maintenance treatment and after active treatment was interrupted for 2 days by placebo using a double-blind randomized design. After a single blind placebo run-in period, hypertensive patients were randomized to amlodipine 5 mg once daily or diltiazem 90 mg twice daily. After 4-6 weeks, doses were increased to 10 mg once daily or 180 mg twice daily, if necessary for control of diastolic blood pressure. During week 9 or 10 on active treatment blisterpacks contained 2 days of placebo. Twenty-four hour blood pressure monitoring was performed at the end of run-in period and during week 9 and 10 on active vs interrupted therapy. 3. Active therapy by amlodipine (n = 20) lowered day systolic blood pressure by 17 +/- 2 mmHg and diastolic blood pressure by 12 +/- 2 mmHg and did not change heart rate. In second day of interrupted therapy most of these responses were still present. Diltiazem (n = 14) lowered day systolic blood pressure by 13 +/- 2 mmHg, diastolic blood pressure by 11 +/- 2 mmHg and heart rate by 10 +/- 2 beats min-1. Most of these responses had disappeared during the second day of interrupted therapy. 4. We conclude that amlodipine and diltiazem are fairly similar in lowering blood pressure from an efficacy point of view. However, during short periods of noncompliance blood pressure control will persist markedly better with the agent with a long vs the one with a short elimination half-life.

Adolescent↗
PubMed1995

Differential effects of felodipine and nifedipine on 24-h blood pressure and left ventricular mass.

1,4-Dihydropyridine calcium antagonists, which have a rapid onset and short duration of action, tend to increase sympathetic activity, which may limit the regression of left ventricular hypertrophy when used for the treatment of hypertension. This study compares the effects of the shorter-acting formulation of nifedipine (PA) with longer-acting felodipine (ER) on 24-h blood pressure and left ventricular mass in patients with uncomplicated essential hypertension. Subjects were randomly allocated to receive nifedipine (n = 52) or felodipine (n = 56) over 8 weeks at increasing doses until the sitting office diastolic blood pressure (DBP) was < 90 mm Hg. An ambulatory blood pressure (ABP) recording and echocardiogram were performed at baseline and upon completion of the study. At the end of the dosing interval, felodipine lowered office DBP (mm Hg) by -18 +/- 12/14 +/- 1 compared to -14 +/- 2/11 +/- 1 for nifedipine (P < or = .05). Mean 24-h ABP was reduced (P < .001) by felodipine (-15 +/- 1/-10 +/- 1 mm Hg) and nifedipine (-15 +/- 1/-9 +/- 2 mm Hg). However, nifedipine caused an apparent biphasic response with felodipine reducing (P < .05) blood pressure more in the early afternoon compared to nifedipine. Left ventricular mass index was significantly reduced (P < .01) by felodipine (-6 +/- 1 g/m2), but not by nifedipine. Once-daily administration of felodipine achieves a more consistent control of blood pressure compared to twice-daily nifedipine and may be associated with a greater reduction in left ventricular mass.

Adult↗
PubMed1995

Swedish population reference standards for height, weight and body mass index attained at 6 to 16 years (girls) or 19 years (boys).

Swedish population reference standards for height, weight and body mass index (BMI) attained at 6 to 16 years (girls) or 19 years (boys) are presented. Data were obtained from two independent nationwide samples of Swedish children; one (740 children) born in 1955, the other (2907 children) born in 1967. The weights of the children born in 1955 were adjusted to equal those born in 1967; heights did not differ. These reference standards refer therefore to Swedish children born at around 1970. The observations were fitted by the power transformation, or L, M, S method of Cole and Green. Weights and BMIs were thus normalized and valid SD scores for individuals obtained. Centile charts are given for clinical use. The means of the present, nationwide standards were 1-2 cm and 1-2 kg greater than those of the Solna-based standards currently in use.

Adolescent↗
PubMed1995

Evaluation of a new, semiquantitative screening culture device for urine specimens.

The EZ Streak urine culture device (Difco Laboratories, Detroit, Mich.) combines the advantages of both the dip-slide and the classic urine culture technique, enabling bacterial enumeration and isolation following a simple inoculation step. Five hundred clean-catch urine specimens submitted by outpatients attending a health maintenance organization were used to compare the EZ Streak with culture using a 0.001-ml loop. Complete agreement of colony counts determined by the two methods was obtained for 114 (91.2%) of 125 positive specimens, but 99.2% of the results agreed in clinical interpretation, indicating the presence or absence of bacteriuria. Overall agreement between the EZ Streak and culture was 95.7%. The sensitivity and specificity of the EZ Streak were determined to be 98.4 and 99.4%, respectively. For this patient population, the EZ Streak was determined to be a reliable replacement for routine urine culture.

Bacteriological Techniques↗
PubMed1995

Oral efficacy of a leukotriene B4 receptor antagonist in colitic cotton-top tamarins.

Leukotriene B4 (LTB4) is a potent neutrophil activator and chemotaxin that is present in increased concentrations in the colonic tissue and rectal dialysates of acute ulcerative colitis patients. Cotton-top tamarins (CTTs) with confirmed active colitis were treated with the second generation LTB4 receptor antagonist, SC-53228 ((+)-(S)-7-[3-(2-cyclopropyl-methyl)-3-methoxy-4-[(methylamino) carbonyl]phenoxy]propoxy]-3,4-dihydro-8-propyl-2H-1-benzopyran-2- propanoic acid), 20 mg/kg bodyweight by gavage, twice daily for 56 days. End points were body weights, stool consistency, colonic endoscopy, assay of inflammatory mediators, and haematology and clinical chemistry tests. LTB4 and prostaglandin E (PGE) values were measured in rectal dialysates at pretreatment, 28 day and 56 day time points. LTB4 concentrations were reduced from pretreatment mean (SEM) values of 37.3 (0.8) ng/ml to 3.7 (0.8) ng/ml (p < 0.001) and 2.3 (0.5) ng/ml (p < 0.01) at days 28 and 56, respectively. On the other hand, mucosal protective PGE values remained constant or slightly increased during SC-53228 treatment (pre: 6.9 (2.2) ng/ml; day 28: 6.7 (1.4) ng/ml; day 56: 9.9 (1.6) ng/ml). Furthermore, assessment of a panel of 35 clinical chemistry and haematology parameters throughout the treatment showed there were no significant untoward effects of drug treatment. Six CCTs finished the eight week treatment and five of six gained weight (ranging from 27-121 grams each) while one CTT lost weight (50 g). Stool condition improved in five of six animals while one of six remained unchanged. All CCTs showed dramatic improvement histologically, with no or only minimally active colitis after treatment. The histological changes plus significant weight gains and improvement of stool condition (quality of life parameters) after eight weeks of SC-53228 treatment were remarkable. Furthermore, in follow up biopsies seven months after treatment ceased, three of six CTTs had no active colitis. This is the first time afflicted CTTs have not had recurring colitic exacerbations after a treatment regimen was stopped. It is concluded that in colitic CTTs, SC-53228 has shown both an immediate and a long acting anticolitic activity. It is also concluded that reduced LTB4 concentrations during treatment inhibited neutrophil infiltration of the colonic tissue and this, coupled with the maintenance of mucosal protective prostaglandins, contributed to the dramatic anticolitic efficacy. The treatment was safe over eight weeks. A compound such as SC-53228 may be useful in the medical treatment of human inflammatory bowel disease.

Animals↗
PubMed1994

Crystallization and preliminary crystallographic analysis of NADPH:FMN oxidoreductase from Vibrio harveyi.

Crystals of NADPH:FMN oxidoreductase from Vibrio harveyi have been obtained and characterized by X-ray diffraction. This enzyme plays a role in the generation of light in luminescent bacteria by providing reduced FMN to luciferase. Large, high quality crystals were grown using polyethylene glycol 6000 at pH 7.0. They crystallize in the monoclinic space group P2(1) with cell dimensions a = 51.2 A, b = 85.9 A, c = 58.1 A, beta = 109.3 degrees, and diffract to 1.8 A. We expect two molecules per asymmetric unit. High resolution data sets have been recorded and a search is under way for heavy-atom derivatives.

Crystallization↗
PubMed1994

2.1 A structure of Serratia endonuclease suggests a mechanism for binding to double-stranded DNA.

The crystal structure of Serratia endonuclease has been solved to 2.1 A by multiple isomorphous replacement. This magnesium-dependent enzyme is equally active against single- and double-stranded DNA, as well as RNA, without any apparent base preference. The Serratia endonuclease fold is distinct from that of other nucleases that have been solved by X-ray diffraction. The refined structure consists of a central layer containing six antiparallel beta-strands which is flanked on one side by a helical domain and on the opposite side by one dominant helix and a very long coiled loop. Electrostatic calculations reveal a strongly polarized molecular surface and suggest that a cleft between this long helix and loop, near His 89, may contain the active site of the enzyme.

Amino Acid Sequence↗
PubMed1994

Standards for height, weight and head circumference from one month to six years based on Stockholm children born in 1980.

Growth data on height, weight and head circumference were collected from Stockholm children from one month to six years of age, born in 1980, and representing all socio-economic groups. The sample consisted of 2471 children (1264 boys and 1207 girls), most of whom were measured on 10-15 occasions. From these measurements centile standards were constructed using a statistical technique which separates between-individual and within-individual variation, since only the former is appropriate to distance standards. Compared to former Swedish standards the present heights and weights were similar up to 2.0 years of age but thereafter considerably greater. Head circumference was larger throughout, perhaps due to a difference in measurement technique.

Body Height↗