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Biomedical subjects

K E Johnson

Publications and source records attributed to K E Johnson.

At least 127 records · Page 7Linked to original sources
PubMedDate not supplied

Etretinate absorption in the in situ perfused intestinal lumen: preliminary studies in the rat.

The absorption characteristics of etretinate were examined in the Sprague-Dawley rat with the use of the in situ intestinal lumen perfusion model. Intestinal segments of 15-50 cm were cannulated and perfused with etretinate solutions of 178-1405 micrograms ml-1 in a single-pass manner at flow rates of 0.15-0.96 ml min-1. The intestinal effluent was collected and analyzed by HPLC for etretinate, as was blood that was drawn from the jugular vein. Despite its lipophilic nature, etretinate does not appear to be well absorbed from the rat intestine; the maximum fraction disappearing from the intestinal lumen was approximately 0.35. The absorption of etretinate appeared to be controlled by the aqueous diffusion layer. There was no evidence that the uptake of etretinate by the gastrointestinal membrane involved an active transport system.

Acitretin↗
PubMedDate not supplied

Economic and gastrointestinal safety comparisons of etodolac, nabumetone, and oxaprozin from insurance claims data from patients with arthritis.

This study was conducted to compare the effect of etodolac, nabumetone, and oxaprozin use on gastrointestinal (GI) safety and associated costs based on insurance claims information from practice settings. Data were obtained from a national claims database (MarketScan) for the years 1992 to 1994. The claims data of interest were for patients with arthritis who had used etodolac, nabumetone, or oxaprozin exclusively during a 9-month follow-up period (ONLY groups), or these drugs plus (PLUS groups) the other nonsteroidal anti-inflammatory drugs (NSAIDs) ibuprofen, naproxen, diclofenac, sulindac, piroxicam, ketoprofen, or indomethacin. For each group, we obtained information on the use of inpatient and outpatient services for GI-related events and the associated costs. All GI admissions were classified as NSAID-induced or possibly NSAID-induced events based on International Classification of Diseases, Ninth Revision, Clinical Modification (ICD-9 CM) codes. All outpatient upper GI ulcers or bleeding episodes were also identified by specific ICD-9 CM code. There were no significant between-group demographic differences. The proportions of patients with NSAID-induced and possibly NSAID-induced GI admissions were 0.1% and 0.4% for the etodolac-ONLY, 0.3% and 1.0% for the nabumetone-ONLY, and 0.1% and 0.5% for the oxaprozin-ONLY groups, respectively (P > 0.05), and a similar pattern was observed among the PLUS groups. In outpatient settings, 3.9%, 4.2%, and 4.9% of the etodolac-, nabumetone-, and oxaprozin-ONLY patients, respectively (P > 0.05), and 6.0%, 5.3%, and 4.7% of the etodolac-, nabumetone-, and oxaprozin-PLUS patients, respectively, had at least one upper GI ulcer/bleeding claim (P > 0.05). The total health care costs for 9 months were approximately $3000 each for the etodolac-, nabumetone-, and oxaprozin-ONLY groups. Oxaprozin, nabumetone, and etodolac had similar GI-safety and associated-costs profiles based on information from practice settings. Also, in patients who used multiple NSAIDs, the groups did not differ in their GI-safety and cost profiles.

Adult↗
PubMedDate not supplied

Experimental manipulation of a contact guidance system in amphibian gastrulation by mechanical tension.

Contact guidance has been implied in various morphogenetic movements including neural crest cell migration, primordial germ cell migration and guidance of axonal growth cone. In urodele gastrulae, we reported the presence of an aligned network of extracellular fibrils on the inside of the ectodermal layer and suggested that it guides the migration of the presumptive mesodermal cells from the blastopore towards the animal pole. We also reported in vitro experiments in which the fibril network of the ectodermal layer was transferred onto the surface of a coverslip. Dissociated mesodermal cells attach to and locomote actively on such conditioned surfaces in an oriented fashion along the blastopore-animal pole axis (bp-ap axis) of the ectodermal layer that conditioned the surface. Recent reports suggest that these fibrils contain fibronectin. We now report that the fibril network on the conditioned surface can be artificially aligned in any orientation by exerting mechanical tension on the ectodermal layer during the conditioning. Such prepared surfaces cause cell movements aligned along the tension axis, even when the tension axis is perpendicular to the natural axis of alignment along the bp-ap axis. These results suggest that the extracellular matrix fibrils aligned by the mechanical stress that arises in embryos during development can orient cell migration by the contact guidance, in a similar manner to that reported in the collagen gel and fibroblasts system.

Ambystoma↗
PubMedDate not supplied

Computed tomography of necrotizing meningoencephalitis in 3 Yorkshire Terriers.

A necrotizing meningoencephalitis of Yorkshire terriers has recently been reported in 6 dogs in Switzerland, 1 dog in Japan and 1 dog in the United States. The purpose of this report is to describe the computed tomographic (CT) findings in 3 dogs with this disease, and to correlate the CT abnormalities with the clinical and pathologic findings in each case. Three Yorkshire Terriers between 2 and 10 years old were evaluated. Physical and neurologic examinations, complete blood count (CBC), serum biochemistry profile, cerebrospinal fluid analysis, and CT scan were performed on all 3 dogs. Brainstem auditory evoked responses (BAER) were evaluated for 2 dogs. Two dogs were euthanized at the owners' request and necropsies were performed. Neurologic examination findings were consistent with a multifocal/diffuse encephalitis involving the cerebrum and brainstem in all 3 dogs. Complete blood count and biochemistry profiles were normal. Elevated protein concentration and a mononuclear pleocytosis were demonstrated in 2 of 3 dogs on cerebrospinal fluid evaluation. Multifocal, extensive areas of decreased opacity throughout the cerebral hemispheres, asymmetric ventriculomegaly, and lack of contrast enhancement were appreciated on CT images of all three dogs. No mass effect was seen. These findings correlated well with pathologic findings at necropsy, which included multiple malacic cavitations within the brain, representing areas of locally extensive necrosis. CT abnormalities in combination with signalment, clinical findings and cerebrospinal fluid analysis should facilitate a presumptive diagnosis of Yorkshire Terrier necrotizing meningoencephalitis.

Animals↗
PubMedDate not supplied

The Nimbus Hemopump: a new left ventricular assist device that combines myocardial protection with circulatory support.

Recent advances in hemodynamic support can allow patients at high risk for cardiovascular collapse to become candidates for coronary interventions. A new axial blood flow pump has recently been developed and made available for clinical testing. This intravascular pump utilizes an Archimedes screw pump rotating at 25,000 rpms to provide a flow of 2 to 3.5 liters/minute. The 7 mm inlet cannula of the cable driven pump is delivered across the aortic valve. The pump discharges blood into the descending aorta. This design does not require a membrane oxygenator. This pump would be expected to: 1) provide circulatory support irrespective of heart arrhythmias; 2) provide left ventricular unloading and 3) lack the fluid and coagulation abnormalities of prolonged cardiopulmonary bypass. This unique device offers great promise to the interventional cardiologist.

Angioplasty, Balloon, Coronary↗
PubMedDate not supplied

Current functional status of Symbion total artificial heart recipients after transplantation.

This multicenter study examines long-term data from the five most experienced North American centers (> 8 total artificial heart [TAH] implants), investigating the functional status of 37 patients who received a Symbion TAH followed by a heart transplant (TX) with post-TX survival > or = 1 year. Primary indications for TAH use included acute cardiogenic shock in 38% (14/37) of patients and deterioration while on the TX waiting list in 35% (13/37). At the time of this study, 86% (32/37) of patients were alive, 94% of whom were functioning at a New York Heart Association (NYHA) classification of I (75% [24/32]) or II (19% [6/32]). NYHA classification before death was I for all five patients who died 40 +/- 17 (r = 14-58) months after transplant. Of the 32 surviving patients, 47% (15) were working, 16% (5) were retired, 12% (4) chose not to work, and 9% (3) were in school. The remaining 16% (5) were unable to work due to surgical limitations. After TX, significant infections occurred in 81% (26/32) of patients and rejection in 72% (23/32). At 1 year after TX, creatinine was within normal limits (< or = 1.4 mg/100 ml or 65-125 mol/L) for 41% (13/32) of patients, 1-2 times normal for 56% (18/32), and > 2 times normal for 3% (1/32). Although TAH is not required for most patients awaiting TX, the device allows excellent long-term functional status in patients otherwise at risk for death. No long-term problems related to the use of temporary mechanical circulatory support were found.

Adolescent↗
PubMedDate not supplied

Registry report. Use of total artificial hearts: summary of world experience, 1969-1991.

Eleven models of total artificial hearts (TAHs) have been used for transient or permanent circulatory support in patients with failing hearts. From April 4, 1969 to July 1, 1991, 230 TAHs were used in 226 patients (four patients received a second TAH) at 39 centers worldwide. Five patients received a Symbion TAH as a permanent circulatory support device; the remaining 221 received TAHs as bridges to cardiac transplantation. The principal investigators received written requests for demographic and clinical information after each implant and annually thereafter to assess survival. The mean patient age (+/- SD) was 43 +/- 12 years (range, 13-69 years); 88% of patients were men. The primary indications for implantation were deterioration while on a transplant waiting list (34%) and acute cardiogenic shock (33%). The duration of implantation ranged from < 1 to 603 days; 65% received heart transplants. The incidence of infection and embolic events occurring during implantation times were 36% and 9%, respectively (stroke, 5%; transient ischemic attacks 4%). Most deaths were caused by sepsis (33%) and multiorgan failure (32%) during the implantation period; sepsis (36%) and rejection of the donor heart (19%) were responsible for most deaths in patients who died after transplantation. The 1 year survival rate was 37% for all patients receiving a device and 50% for those who received a transplanted organ. In the overall Symbion TAH population (187 patients), 40% survived 1 year and 56% of the transplanted group survived 1 year; 39 non-Symbion TAH implants resulted in one long-term survivor (3%).(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMedDate not supplied

Iron status and pregnancy in a northern Canadian population: relationship to diet and iron supplementation.

To determine the extent of iron deficiency, the prognostic value of prenatal ferritin levels and the desirability of prenatal iron supplementation in the western Canadian arctic, dietary iron intake was determined in 171 women and ferritin levels determined in 121 women during pregnancy, 79 at delivery and 77 postnatally, as well as in 65 of their infants at birth and 74 postnatally. Iron deficiency (ferritin < 15 ng/ml) was present in 34% of women during the first two trimesters, 25% (20/79) at delivery and in 51.7% (15/29) of mothers and 31% (9/29) of infants beyond four months after delivery. Maternal follow-up ferritin levels correlated poorly with dietary iron intake but well with prenatal ferritin levels, which appeared to be good predictors of the effectiveness of supplementation. Mean infant follow-up ferritin levels were 105.6 +/- 115.2 ng/ml with, and 46.7 +/- 63.5 without maternal prenatal supplementation (p = 0.03); maternal, 45.5 +/- 40.9 ng/ml with, and 12.8 +/- 9.2 without (p < 0.001). Measurement of prenatal ferritin levels to determine risk of iron deficiency and routine prenatal iron supplementation are recommended.

Diet↗
PubMedDate not supplied

Summary of the clinical use of the Symbion total artificial heart: a registry report.

Several models of total artificial hearts have been used for transient or permanent circulatory support in patients with decompensation. The most successful and widely used device, however, has been the Symbion total artificial heart. From Dec. 12, 1982, to Jan. 1, 1991, 180 Symbion total artificial hearts were implanted in 176 patients in 28 centers. Five patients received a Symbion total artificial heart as a permanent circulatory support device, whereas 171 patients received the device as a bridge to heart transplantation. Of the 175 bridge devices (171 patients) 141 were Symbion J7-70 hearts and 34 were Symbion J7-100 hearts. Four patients received two total artificial hearts, the second one after the failure of a transplanted heart because of either rejection (two patients) or donor heart failure (2 patients). Most of the recipients were males (152). The age was 42 +/- 12 years (mean +/- SD) with a weight of 74 +/- 14 kg. The most common indications for implantation included deterioration while awaiting heart transplant (36%) and acute cardiogenic shock (32%). The cause of heart disease was primarily ischemic (52%) and idiopathic (35%) cardiomyopathy. Duration of implantation ranged from 0 to 603 days (mean 25 +/- 64 days). One hundred three (60%) patients had the device less than 2 weeks, 37 (22%) between 2 to 4 weeks and 31 (18%) more than 4 weeks. Complications during implantation included infection (37%), thromboembolic events (stroke 7%, transient ischemic attack 4%), kidney failure requiring dialysis (20%), bleeding requiring intervention (26%), and device malfunction (4%). Of the 171 patients, 118 (69%) underwent orthotopic heart transplantation. Actuarial survival for all patients with implants was 62% for 30 days and 42% for 1 year, and for patients with transplants was 72% for 30 days and 57% for 1 year. The main causes of death were sepsis (33%), multiorgan failure (21%), and posttransplant rejection (10%). The results indicate a relative success of this treatment for patients with an otherwise fatal prognosis. Moreover, as the demand for donor organs far exceeds availability, continued investigation of total artificial hearts is justified.

Actuarial Analysis↗
PubMedDate not supplied

The amphibian embryo: an experimental model for the in vivo analysis of interactions between embryonic cells and extracellular matrix molecules.

The early amphibian embryo provides an attractive model for the in vivo analysis of cell interactions with extracellular matrix components. During gastrulation, mesodermal cells use an anastomosing network of extracellular fibrils as substratum for their migration. These fibrils contain glycosaminoglycans and non collagenous proteins including laminin and fibronectin. The function of these extracellular components in the mesodermal cell migration process has been inferred from grafting experiments and microinjection of probes such as specific antibodies or GRGDS-containing peptides. Using the amphibian embryo as an experimental system, combination of microsurgical, cell behavioral and molecular approaches will provide new insights into cell-extracellular matrix interactions directing morphogenetic cell movements.

Amino Acid Sequence↗
PubMedDate not supplied

Early sexual activity among adolescents in small towns and rural areas: race and gender patterns.

A 1987 survey of 758 eighth-grade students from three rural counties in Maryland revealed that 61 percent of males and 47 percent of females have engaged in sexual intercourse, and that 77 percent of black students and 40 percent of whites have ever had intercourse. A logistic regression analyzing the effects of race and gender shows that the odds that young black teenagers would have had intercourse are over five times those for whites, and that the odds for males are about twice those for females. The introduction of developmental, individual, academic and behavioral factors into the regression model has little effect on these odds ratios. Separate logistic analyses of four subgroups--white males, white females, black males and black females--reveal no consistent associations between sexual activity and the factors examined. For example, such types of problem behavior as cigarette smoking and use of alcohol or certain other drugs are associated with the likelihood of sexual activity, but the specific type of behavior involved differs by subgroup: Cigarette smoking is related to an increased likelihood of sexual activity just among white females, while alcohol consumption is associated with sexual experience among black females and white males only. Use of drugs other than marijuana or alcohol is linked to a 5-9 times greater risk of sexual activity among whites, but not to any significantly increased risk among blacks, whereas living in a town (rather than in the country) is significantly associated with the likelihood of sexual intercourse among both white and black males, but not among females of either race.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMedDate not supplied

Nine year experience with the clinical use of total artificial hearts as cardiac support devices.

One hundred sixteen total artificial hearts (TAH) were implanted in 113 patients by 29 centers between April 4, 1969 and March 1, 1988. Five were permanent and 111 were temporary implants (3 patients received second implants). Eight different types of TAHs have been used. The ages ranged from 15 to 62 (mean age: permanent 57, temporary 42). Sixty-seven percent (72/108) of patients receiving the TAH for temporary support were transplanted; 6 patients were waiting for a transplant. Forty-seven percent (34/72) were alive after transplantation. Of the 92 patients receiving the Jarvik TAH (the most frequently used device) as a temporary device, 67% (62/92) were transplanted (6 currently supported) and 55% were alive after transplantation; 85% were back to work, with a normal life-style. The thromboembolic rate for patients who received the device as a temporary support was 10%, with 3 patients having residual sequellae. No deaths resulted from mechanical failure. Experience to date suggests that the use of the TAH as a temporary device can be beneficial if patients are carefully selected.

Adolescent↗