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Biomedical subjects

D John

Publications and source records attributed to D John.

18 recordsLinked to original sources
PubMed2001

Differences among out-of-treatment drug injectors who use stimulants only, opiates only or both: implications for treatment entry.

The goal of this study was to compare drug and alcohol use, psychological symptoms and substance abuse treatment entry among 583 street-recruited, out-of-treatment injection drug users (IDUs) who used stimulants only, opiates only or both stimulant and opiate. Data analyzed from structured interviews indicated that stimulant-only users had the most severe alcohol problems and the highest psychological symptom scores for hostility, paranoia and psychoticism. In the 2 months following their interview only 3% of the stimulant-only users entered substance abuse treatment, as compared to nearly half of the participants in the other two groups. Even after controlling for variables that differed among the groups by logistic regression analysis, stimulant only users were still 24-25 times less likely than opiate only or both stimulant and opiate users to enter treatment. Researchers and clinicians are challenged to better understand and address the unique needs of stimulant users, including potential psychological problems and alcohol abuse, in order to attract them to treatment and serve them through a comprehensive treatment approach.

Adult↗
PubMed2001

MR imaging as the sole preoperative imaging modality for right hepatectomy: a prospective study of living adult-to-adult liver donor candidates.

OBJECTIVE: Our aim was to investigate the feasibility of MR imaging as a comprehensive preoperative imaging test for examination of liver donor candidates for adult-to-adult right lobe transplantation. SUBJECTS AND METHODS: Twenty-five consecutive donor candidates were examined at 1.5 T using a torso phased array coil with breath-hold T1- and T2-weighted imaging of the abdomen, MR cholangiography using T2-weighted turbo spin-echo imaging, and MR angiography and venography of the liver using two interpolated three-dimensional spoiled gradient-echo sequences (average dose of gadolinium contrast material, 0.17 mmol/kg). Images were interpreted for liver parenchymal and extrahepatic abnormalities; measurements of right and left lobe liver volumes; definition of hepatic arterial, portal venous, and hepatic venous anatomy; and definition of the biliary branching pattern. Findings were compared with those of conventional angiography in 13 patients, 11 of whom also had surgical findings for comparison. RESULTS: Nine patients were excluded as candidates for donation on the basis of MR imaging findings that included parenchymal or extrahepatic abnormalities in five patients, vascular anomalies in two, and biliary anomalies in three. Two patients who did not undergo surgery underwent conventional angiography that confirmed MR angiographic findings except for a small (<2 mm) accessory left hepatic artery missed on MR imaging. Of the nine patients who underwent successful right hepatectomy, all MR imaging findings were corroborated intraoperatively. In two patients, right hepatectomy was aborted at laparotomy because of intraoperative cholangiography findings; in one of them, the biliary finding was unsuspected on MR imaging. CONCLUSION: A comprehensive MR imaging examination has the potential to serve as the sole preoperative imaging modality for living adult-to-adult liver donor candidates provided improvements in definition of intrahepatic biliary anatomy can be achieved.

Adult↗
PubMed1999

Infectious keratitis in leprosy.

AIM: To describe leprosy characteristics, ocular features, and type of organisms that produce infective corneal ulcers in leprosy patients. METHOD: The records of all leprosy patients admitted for treatment of corneal ulcers between 1992 and 1997 were reviewed. RESULTS: 63 leprosy patients, 53 males and 10 females, are described. 16 were tuberculoid and 47 lepromatous. 25 patients had completed multidrug therapy. 10 patients had face patches, eight had type I reaction, and 10 had type II reaction. 43 (68%) patients had hand deformities. In 54% of patients pain was absent as a presenting symptom. 19 patients gave a history of trauma. In 15 patients ulcers had also occurred on the other eye, five of them having occurred during the study period and the rest before 1992. Of the 68 eyes with corneal ulcers, 28 had madarosis, 34 had lagophthalmos, nine had ectropion, three had trichiasis, six had blocked nasolacrimal ducts, and 39 decreased corneal sensation. In 14 eyes, a previous lagophthalmos surgery had been done. 16 patients were blind at presentation. 32% of ulcers were located centrally. After treatment only 18% of the eyes showed visual improvement. Five types of fungus were cultured, two of them rare ocular pathogens. CONCLUSIONS: Corneal ulcers occur more in males and in the lepromatous group of patients. Decreased corneal sensation, lagophthalmos and hand deformity are closely associated. Indigenous treatment and late presentations were notable in many patients. Visual outcome is not good. There is increased risk of developing an ulcer in the other eye. Fungal corneal ulcers are not uncommon.

Adult↗
PubMed1999

HIV/AIDS risks among Native American drug users: key findings from focus group interviews and implications for intervention strategies.

A multisite study funded through the National Institute on Drug Abuse and the Office of Research on Minority Health was conducted in 1996 to determine the HIV/AIDS prevention needs of Native American out-of-treatment drug users. In an effort to recommend directions for HIV/AIDS prevention programming, one component of this study entailed conducting a series of focus groups at each of four sites: Anchorage, Alaska; Denver, Colorado; Flagstaff, Arizona; and Tucson, Arizona. While some site differences were noted, several consistent thematic findings were revealed across all locations. Specifically, focus group members strongly recommended directly involving key members of the Native American community in conducting outreach and intervention activities, involving Native people as the sources of information, and utilizing local and tribally relevant forms of delivering the message. Other consistent themes included getting messages to smaller communities to prevent the potential "annihilation" of tribes, educating youth, and linking alcohol prevention education to HIV/AIDS education. Findings from this study support the idea that future HIV/AIDS prevention programs must take into account subgroup and individual level differences among Native American drug users.

Acquired Immunodeficiency Syndrome↗
PubMed1998

Facilitating treatment entry among out-of-treatment injection drug users.

OBJECTIVE: High risk injection practices are common among injecting drug users (IDUs), even following intervention efforts. Moreover, relapse to risk behaviors has been reported among those who initiate risk reduction. Substance abuse treatment offers the potential to reduce or eliminate injecting risk behaviors through drug cessation. We report on the effectiveness of two intervention strategies in facilitating treatment entry among out-of-treatment IDUs: motivational interviewing (MI), and intervention developed to help individuals resolve their ambivalence about behavior change, and free treatment for 90 days. These conditions were compared with an intervention focusing on a hierarchy of safer injecting practice, referred to here as risk reduction (RR), and no free treatment. METHODS: Nearly 200 out-of-treatment IDUs were randomly assigned to one of four experimental conditions: MI/free treatment, MI/no free treatment, RR/free treatment, and RR/no free treatment. Regardless of assignment, we assisted anyone desiring treatment by calling to schedule the appointment, providing transportation, and waiving the intake fee. RESULTS: Overall, 42% of study participants entered treatment. No significant differences were found between MI and RR; however, 52% of those assigned free treatment entered compare with 32% for those who had to pay. Other predictors of treatment entry included prior treatment experiences, perceived chance of contracting acquired immunodeficiency syndrome (AIDS) greater than 50%, "determination" stage of change, greater frequency of heroin injecting, and fewer drug-using friends. CONCLUSIONS: These findings support the importance of removing barriers to treatment entry.

Adolescent↗
PubMed1995

[Hemodilution in treatment of intrauterine dystrophy].

It was the aim of the study to show that HES (Hydroxy-Ethyl-Starch) in intrauterine dystrophy identified by ultrasonography can increase fetal growth. Twenty pregnant women were treated in two groups (outpatients versus inpatients). Clinically, the result was satisfying.

Adult↗
PubMed1994

Synthesis and evaluation of amino analogues of valproic acid.

Valproic acid, an antiepileptic drug, is extensively metabolized in humans. Two putative metabolites, 2-n-propyl-3-aminopentanoic acid (3-aminovalproic acid, 3-amino-VPA; 2a) and 2-n-propyl-4-aminopentanoic acid (4-amino-valproic acid, 4-amino-VPA; 4a), which may result from the transamination of the respective keto acids 1a and 3a may explain the unusual extended seizure protection elicited by valproic acid. The title compounds were synthesized as their diasteriomeric ethyl esters 2b and 4b and submitted for anticonvulsant evaluation by the Antiepileptic Drug Development Program of the National Institute of Neurological and Communicative Disorders and Stroke. The results verified our hypothesis, as 4b was active in the subcutaneous pentylenetetrazol (scMet) evaluation at 30 mg/kg. Both compounds were highly toxic at 300 mg/kg.

Animals↗
PubMed1994

[Not Available].

Explore the source record for details and available documents.

Germany↗
PubMed1989

Back injuries to fast bowlers in cricket: a prospective study.

Eighty-two high performance young male fast bowlers (mean age 16.8 years) were tested immediately prior to the season for selected kinanthropometric and physiological data. Subjects were also filmed both laterally (200 Hz) and from above (100 Hz) while bowling so that their front foot impacted a force platform during the delivery stride. The players then completed a log book over the ensuing season that detailed their training and playing programmes. All cricket related injuries over this season were assessed by a sports physician who used computerized tomography to assist in the diagnosis of spinal injuries. At the completion of this season the players were grouped according to their injury status (Group 1--bony injury to a vertebra; Group 2--soft tissue injury to the back that caused the player to miss at least one game, and Group 3--no injuries). A one-way analysis of variance was used to identify if any variables were significantly (P less than 0.05) different between the three groups, and a Scheffe post hoc comparison was used to determine which groups were significantly different. Eleven per cent of the players sustained a stress fracture to a vertebra(e) (L4 to S1), while 27 per cent sustained a soft tissue injury to the back. Bowlers with a low longitudinal foot arch were more likely to develop a stress fracture than those with a high arch. Shoulder depression and horizontal flexion strength for the preferred limb and quadriceps power in the non-preferred limb were also significantly related to back injuries. Results suggest that bowlers with the above physical characteristics, who bowl with these biomechanical techniques for extended periods, are predisposed to back injuries.

Adolescent↗
PubMed1989

Prednisone when used as treatment for rejection correlates with poor outcome.

Since January 1974, 195 of 202 (95%) renal transplants have been performed on blacks at the Howard University Hospital Transplant Center. Hypertension is the most common cause of end-stage renal disease (ESRD) at this center (57%). The immunosuppressive regimens utilized were divided into four eras. The first era (1974-1980) consisted of the prophylactic administration of prednisone, Imuran (AZA), and Minnesota antilymphocyte globulin (MAG) with high prednisone dosage used to treat rejection. One-year, two-year, and five-year patient survival rates were 59% 54%, and 41%, respectively. Graft survival rates for the same period were 53%, 47%, and 36%. In the second era (1980-1983), the same immunoprophylaxis was used but only MAG was used to reverse rejection. One-year and two-year patient survival rates were 90% and 84%. Graft survival rates for the same period were 72% and 64%. When era 1 is compared with era 2, statistically significant improvement in patient survival is evident (P less than 0.005). Graft survival rates are statistically significant for one-year graft survival (P less than 0.05). In the third era (1983-1986), cyclosporine was the principal immunosuppressive agent used along with prednisone. Rejection in this era was treated by adjusting the cyclosporine dose to keep the level between 100 ng to 150 ng per mL and in addition to high prednisone. One-year patient survival and graft survival rates were 83% and 55%, respectively. The fourth era began April 1986 and was initiated because of previous bad experiences with high doses of prednisone to treat rejection in era 1.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1987

Hypoxanthine causes a 2-cell block in random-bred mouse embryos.

Ham's F-10, a chemically defined, complex culture medium, commonly used for in vitro fertilization of human as well as animal oocytes, blocked development at the 2-cell stage of greater than 92% of embryos from random-bred Swiss mice (CD-1), but did not block development of embryos from hybrid-inbred mice (BDF1). In contrast, BWW, a simple, modified Kreb's-Ringer bicarbonate medium, supported development to blastocysts of 85% and 100% of 2-cell embryos from CD1 and BDF1 females, respectively. As little as 15% (v/v) Ham's F-10 added to the BWW blocked the development of the random-bred embryos. Supplementing the BWW with Ham's F-10 components revealed that hypoxanthine (6-30 microM) was responsible for the developmental block to the random-bred embryos. The hypoxanthine block was partially (40%) reversed by adding the chelating agent, ethylenediaminetetraacetic acid. Breeding experiments showed that the hypoxanthine sensitivity of embryos from CD-1 mothers was not affected by the paternal genome.

Animals↗
PubMed1986

Characteristics of high affinity and low affinity adenosine binding sites in human cerebral cortex.

The binding characteristics of human brain cortical membrane fractions were evaluated to test the hypothesis that there are A1 and A2 adenosine binding sites. The ligands used were 2-chloro[8-3H]adenosine and N6-[adenine-2,8-3H]cyclohexyladenosine. Binding of chloroadenosine to human brain cortical membranes was time dependent, reversible and concentration dependent. The Kd calculated for chloroadenosine by Scatchard analysis of equilibrium data was 280 nM, with a Bmax of 1.6 pmoles/mg protein, suggesting a single class of binding sites. The specificity of chloroadenosine binding was assessed by the ability of adenosine analogs to compete for binding sites. Using this approach, the apparent Kd was estimated to be 0.74 microM for 5'-N-ethyl-carboxamideadenosine, 1 microM cyclohexyladenosine, and 13 microM for N6-(L-2-phenylisopropyl)adenosine. Isobutylmethylxanthine and theophylline, receptor antagonists, had apparent Kd values of 84 microM and 105 microM, respectively. Hill slope factors ranged from 0.3 to 0.6. Chloroadenosine binding to human brain cortical membranes approached equilibrium at 90 minutes, with a T1/2 of 10 minutes. The kob was 0.080 min-1 and the k1 was 7.5 X 10(4) min-1 M-1. Reversibility of chloroadenosine binding at equilibrium was completed at approximately 10 minutes with a k2 value of 0.074 min-1. The Kd calculated from the rate constants was 990 nM. Cyclohexyladenosine binding was concentration dependent. The Kd calculated for cyclohexyladenosine via Scatchard analysis of equilibrium data was 5 nM with a Bmax of 0.35 pmoles/mg protein. Cyclohexyladenosine binding was displaced by 3 known receptor agonists: N6-(L-2-phenyliso propyl)adenosine (Kd 4 nM), 2-chloroadenosine (Kd 10 nM) and 5H-N-ethyl-carboxamideadenosine (Kd 6 nM). The apparent Kd values for the agonists were 1 to 3 orders of magnitude lower with this ligand as compared to radioactive chloroadenosine. Binding was also displaced by 2 known antagonists, isobutylmethylxanthine and theophylline, with apparent Kd values of 4 microM and 8 microM, respectively. Hill slope factors ranged from 0.5 to 0.8. Our data support the existence of two adenosine binding sites in human cortex compatible with the low affinity (A2) and high affinity (A1) adenosine receptors.

1-Methyl-3-isobutylxanthine↗
PubMed1985

Hyperuricemia and hypertriglyceridemia: metabolic basis for the association.

Hypertriglyceridemia has been reported frequently in patients with hyperuricemia and gout. The current studies have evaluated this relationship. To examine whether hypertriglyceridemia leads to hyperuricemia, IV intralipid was given to three gouty patients. Triglycerides increased from 169 to 700 mg/dl for three hours but caused no change in serum urate level or urine uric acid and oxypurine excretion. We next examined whether high carbohydrate intake increases serum urate and triglyceride levels. Four obese patients were placed on a 2000 kcal/d sucrose diet for seven days. The serum urate increased from 6.3 +/- 1.7 to 7.9 +/- 2.0 mg/dL. The percent uric acid clearance to creatinine clearance decreased from 5.9 +/- 1.3 to the lowest mean value of 3.7 +/- 1.2, while serum triglycerides increased from 106 +/- 33 to 252 +/- 57 mg/dL and blood lactate from 607 +/- 227 to 1167 +/- 381 mumol/L. A 3000 kcal/d glucose diet in four other obese subjects produced no change in serum urate levels but increased lactate and triglyceride levels. During an isocaloric sucrose diet in two normal men, the serum urate level increased from 5.3 and 4.0 to peak values of 9.5 and 7.4 mg/dL. The percent uric acid to creatinine clearance decreased from 5.6 and 6.6 to 2.9 and 3.3. The uric acid turnover did not increase. In three gouty patients the mean serum urate increased from 8.5 +/- 1.5 to 10.6 +/- 1.4 mg/dL following an isocaloric sucrose diet. The urine uric acid excretion increased from 0.30 and 0.25 to 0.37 and 0.38 mg/mg creatinine in two patients.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1985

Characteristics of high-affinity and low-affinity adenosine binding sites in human cerebral cortex.

The binding characteristics of human brain cortical membrane fractions were evaluated to test the hypothesis that there are A1 and A2 adenosine binding sites. The ligands used were 2-chloro[8-3H]adenosine and N6-[adenine-2,8-3H]cyclohexyladenosine. Binding of chloroadenosine to human brain cortical membranes was time dependent, reversible, and concentration dependent. The dissociation constant (Kd) calculated for chloroadenosine by Scatchard analysis of equilibrium data was 280 nmol/L, with a maximum binding (Bmax) of 1.6 pmol/mg protein, suggesting a single class of binding sites. The specificity of chloroadenosine binding was assessed by the ability of adenosine analogues to compete for binding sites. With this approach, the apparent Kd was estimated to be 0.74 mumol/L for 5'-N-ethylcarboxamideadenosine, 1 mumol/L for cyclohexyladenosine, and 13 mumol/L for N6-(L-2-phenylisopropyl)adenosine. Isobutylmethylxanthine and theophylline, receptor antagonists, had apparent Kd values of 84 mumol/L and 105 mumol/L, respectively. Hill slope factors ranged from 0.3 to 0.6. Chloroadenosine binding to human brain cortical membranes approached equilibrium at 90 minutes, with a t 1/2 of 10 minutes. The kob was 0.080/min, and the k1 was 7.5 X 10(4)/min/mol/L. Reversibility of chloroadenosine binding at equilibrium was completed at approximately 10 minutes, with a k2 value of 0.074/min. The Kd calculated from the rate constants was 990 nmol/L. Cyclohexyladenosine binding was concentration dependent. The Kd calculated for cyclohexyladenosine via Scatchard analysis of equilibrium data was 5 nmol/L with a Bmax of 0.35 pmol/mg protein. Cyclohexyladenosine binding was displaced by three known receptor agonists: N6-(L-2-phenylisopropyl)adenosine (Kd 4 nmol/L), 2-chloroadenosine (Kd 10 nmol/L) and 5'-N-ethylcarboxamideadenosine (Kd 6 nmol/L).(ABSTRACT TRUNCATED AT 250 WORDS)

2-Chloroadenosine↗
PubMed1984

Evidence for an adenosine receptor in human tissues.

Our observations suggest that [3H] chloroadenosine, an adenosine receptor agonist, identifies binding sites in human placenta with characteristics of the high affinity, adenosine receptor. The binding is time dependent, reversible and saturable. The potency series of adenosine receptor methylxanthine antagonists in displacing [3H] chloroadenosine is appropriate.

Adenosine↗