PubMed Health⌕ Search

Biomedical subjects

J Hendrix

Publications and source records attributed to J Hendrix.

11 recordsLinked to original sources
PubMed2001

Reliability of fractional flow reserve measurements in patients with associated microvascular dysfunction: importance of flow on translesional pressure gradient.

Fractional flow reserve (FFR) has been applied with success as a lesion-specific functional indicator of stenosis severity, at least in patients with normal microcirculation. This study sought to assess the reliability of FFR calculations in patients with associated microvascular dysfunction (e.g., post myocardial infarction, or post-MI). First, the effect of coronary flow changes on translesional pressure gradient was assessed. Therefore, intracoronary pressure and flow was recorded simultaneously across 19 non-infarct-related lesions (both pre- and postinterventional lesions with a mean diameter stenosis of 47% +/- 12%). Measurements were performed by means of a pressure and Doppler wire during maximal hyperemia and also during submaximal hyperemia induced by low-dose adenosine. The drop of coronary flow from 48 +/- 23 ml/min during maximal hyperemia to 36 +/- 18 ml/min during submaximal hyperemia was associated with a small decrease in translesional pressure gradient (from 22 +/- 12 mm Hg to 19 +/- 12 mm Hg; P = 0.02) and a small increase in the mean distal/arterial pressure ratio (Pd/Pa) going from 77% +/- 11% to 81% +/- 11% (P = 0.003). Then, intracoronary pressure and flow measurements were compared across 21 non-infarct-related lesions vs. 22 matched infarct-related lesions. For a similar angiographic stenosis severity (% DS = +/- 44%), maximal flow was 48 +/- 22 ml/min in the non-infarct arteries and 37 +/- 26 ml/min in the infarct arteries (P = 0.03), confirming the presence of severe microvascular dysfunction in infarct regions. Similar to the earlier findings, this hyperemic flow reduction in MI patients was associated with a small increase of FFR (= Pd/Pa): 79% +/- 12% in no MI vs. 83% +/- 12% in MI patients (P = 0.3). A reduction of hyperemic flow by +25%, [correction] such as can be found in patients with severely impaired microvascular function, has a limited effect on FFR calculations (+ 5%). This finding allows the application of standard FFR calculations in a more general population of ischemic heart disease, including patients with recent MI.

Aged↗
PubMed1998

Insulin allergy resolution following pancreas transplantation alone.

Clinically significant immunological reactions to exogenous insulin are classified as local or generalized. Most of the insulin allergies are local reactions which usually improve or resolve spontaneously. Generalized allergic reactions to insulin range in severity from simple urticaria to life-threatening anaphylaxis. Most of the allergic reactions to exogenous insulin are antibody-mediated reactions to antigens such as zinc, protamine, non-insulin proteins, and aggregates of insulin molecules as well as animal antigens. Immunologic reactions to endogenous insulin usually result in insulin resistance. Herein, we report a case in which systemic insulin allergy was intractable, thus requiring a pancreas transplantation which is the first of its case according to the International Pancreas Transplant Registry/United Network for Organ Sharing (IPTR/UNOS) Registry.

Adult↗
PubMed1993

Impact of bone density corrections on target dose delivered to the prostate with 4 MV, 6 MV, 10 MV, and 18 MV photons.

Doses for definitive prostate irradiation have been derived empirically using low-energy megavoltage equipment without availability of bone density corrections. With their increased availability, higher energy photons are being used more frequently because of their improved depth of penetration. Although inhomogeneity corrections lead to greater accuracy of dose delivery, the clinical utility of corrections in the pelvis is unclear. This study evaluates the effect of bone density on the dose delivered with respect to the photon energy employed. Contours and volumes for 10 patients were taken from computed tomography scans at the center of the prostate gland. Treatment plans for bilateral prostate arc fields were run on the Capintec Treatment Planning System for 4, 6, 10, and 18 MV photon energies. The monitor units needed to deliver 6500 cGy to isocenter without bone correction were used for calculations, both with and without bone correction using the equivalent path length algorithm. The median dose to the isocenter was 6500 cGy for all energies without bone correction. The median doses using the uncorrected monitor units for the 4 MV, 6 MV, 10 MV, and 18 MV photon beams corrected for bone density were 6033, 6062, 6166, and 6228 cGy, respectively. The variance in target doses observed in our patient sample was +/- 2.3%, +/- 2.2%, +/- 1.7%, and +/- 1.4%, respectively, for the 4 MV, 6 MV, 10 MV, and 18 MV beams with bone correction. The increased density of bone in the pelvis does alter the actual dose to the prostate from external beam treatment.(ABSTRACT TRUNCATED AT 250 WORDS)

Bone Density↗
PubMed1992

Incidence, mechanism of injury, and treatment of fractures of the patella in children.

Fractures of the patella in skeletally immature patients are rare. The charts of 185 patients treated for patella fractures at the University of Kentucky Medical Center between 1976 and 1988 were retrospectively reviewed. The 12 patients of these 185 aged 8 to 16 years were included in this study. The incidence was calculated to be 6.5% of all patella fractures. All patients studied were male with an average age of 12.7 years. Sleeve fractures were the most common type of patella fracture observed (five), followed by transverse fractures (four). Ten of the 12 cases required operative management ranging from irrigation and debridement to open reduction and internal fixation. Partial patellectomy was performed when indicated. Indications for operative management in this age group were similar to those for adults. As in adults, the mechanism of injury was predominantly motor vehicle and motorcycle crashes. Laws requiring seatbelt restraints for children should have a positive effect on the incidence of such fractures resulting from dashboard injuries. One mechanism of injury not reported previously was that of a flexed knee striking the gym wall after performing a basketball lay-up because the basket was placed flush with the wall.

Accidents, Traffic↗
PubMed1990

Zidovudine therapy in an inner city population.

To determine the compliance and tolerance with zidovudine (azidothymidine or AZT) therapy among poor, minority, and intravenous drug-using patients, data were collected on all AIDS and ARC patients followed for at least 4 weeks in a New York City Human Immunodeficiency Virus clinic. Ninety-nine patients received zidovudine, of whom 75% were males, 92% were minorities, and 59% had a history of intravenous drug use. Of the 99 patients, 72 had AIDS and 27 had ARC with T-helper (CD4) lymphocytes less than or equal to 500 mm3. Eighty-seven of the 99 patients (88%) were compliant with zidovudine therapy. Fifty-seven percent of these had at least one adverse drug reaction requiring dose reduction (44%) or cessation (13%). Adverse reactions were similar to those reported in other populations with HIV-related illness, although headache and nausea were less common. Twenty opportunistic infections (OIs) or HIV-related malignancies occurred in 15 of 82 (18%) patients who were on zidovudine for at least 4 weeks (7.6 OIs/1,000 patient weeks). Seven of the 82 died (9%), compared to 9 of the 17 patients (53%) who did not complete 4 weeks of zidovudine therapy (p less than 0.05). There were no significant differences in any of these measures when intravenous drug users were compared with other risk groups. We conclude that zidovudine can be administered to intravenous drug users and others in an inner city clinic with acceptable compliance and tolerance.

AIDS-Related Complex↗
PubMed1988

Psychological and social complaints reported by Dutch patients to their family doctors.

Ninety-three percent of all problems and complaints reported by patients aged 21 and older to their family physician dealt with somatic disorders, and only 7% with psychosocial problems. Psychological complaints were evenly distributed among major age groups, and between male and female patients. "Social problems" peaked in the middle-age range. The most frequently reported psychological problems were feeling anxious, nervous or tense; feeling irritable, angry, restless or agitated; experiencing feelings of depression; and disturbances of sleep. Marital problems, problems at work, and problems caring for an ill or disabled relative were the most frequently reported "social" reasons for encounter. More women than men reported feelings of depression and marital problems. Men more often felt irritable, angry, restless or agitated, and had more problems at work.

Adult↗
PubMed1986

Structural changes during activation of frog muscle studied by time-resolved X-ray diffraction.

The pattern given by contracting frog muscle can be followed with high time resolution using synchrotron radiation as a high-intensity X-ray source. We have studied the behaviour of the second actin layer-line (axial spacing of approximately 179 A) at an off-meridional spacing of approximately 0.023 A-1, a region of the diagram that is sensitive to the position of tropomyosin in the thin filaments. In confirmation of earlier work, we find that there is a substantial increase in the intensity of this part of the pattern during contraction. We find that the reflection reaches half its final intensity about 17 milliseconds after the stimulus at 6 degrees C. The changes in the equatorial reflections, which arise from movement of crossbridges towards the thin filaments, occur with a delay of about 12 to 17 milliseconds relative to this change in the actin pattern. In over-stretched muscle, where thick and thin filaments no longer overlap, the changes in the actin second layer-line still take place upon stimulation with a time course and intensity similar to that observed at full overlap. This indicates that tropomyosin movement, in response to calcium binding to troponin, is the first structural step in muscular contraction, and is the prerequisite for myosin binding. A change in intensity similar to that found in contracting muscle is seen in rigor, where tropomyosin is probably locked in the active position. During relaxation the earlier stages in the decrease in intensity of the second actin layer-line take place significantly sooner after the last stimulus than tension decay. In over-stretched muscles the intensity decay is appreciably faster than in the same muscles at rest length, where attached crossbridges may interfere with the return of tropomyosin to its resting position.

Actins↗