PubMed Health⌕ Search

Biomedical subjects

J Long

Publications and source records attributed to J Long.

At least 91 records · Page 5Linked to original sources
PubMed1996

Using hybrid magnetic bearings to completely suspend the impeller of a ventricular assist device.

Clinically available blood pumps and those under development suffer from poor mechanical reliability and poor biocompatibility related to anatomic fit, hemolysis, and thrombosis. To alleviate these problems concurrently in a long-term device is a substantial challenge. Based on testing the performance of a prototype, and on our judgment of desired characteristics, we have configured an innovative ventricular assist device, the CFVAD4, for long-term use. The design process and its outcome, the CFVAD4 system configuration, is described. To provide unprecedented reliability and biocompatibility, magnetic bearings completely suspend the rotating pump impeller. The CFVAD4 uses a combination of passive (permanent) and active (electric) magnetic bearings, a mixed flow impeller, and a slotless 3-phase brushless DC motor. These components are shaped, oriented, and integrated to provide a compact, implantable, pancake-shaped unit for placement in the left upper abdominal quadrant of adult humans.

Biocompatible Materials↗
PubMed1996

Experiences in the first year. Community hospital pediatric trauma center.

Demographic and outcome variables of children seen in a community hospital Level II pediatric trauma center are described and patterns of injury classified according to different mechanisms. Records were reviewed retrospectively of 184 patients seen over a one year period, 63% were male and the peak age group was 13-15 years (31%). Descriptive and nonparametric statistics were used to analyze the data. Mechanisms of injury included pedestrian vs auto (27%), falls (23%), motor vehicle occupants (18%), bicycle vs auto (17%), sports injuries (3%), motorcycle crashes (2%), gunshot wounds (2%), and stabbings (2%). Penetrating injuries had higher average trauma scores but blunt injuries were associated with higher mortality. Demographics and mechanisms of injury were similar to national studies. Emphasis on the use of pediatric trauma scores by emergency medical personnel is suggested to decrease the over-triage rate. The frequency of bicycle injuries and lack of helmet use prompted a major helmet promotion campaign.

Accidental Falls↗
PubMed1996

Prenatal cocaine and neonatal outcome: evaluation of dose-response relationship.

OBJECTIVE: The aim of this study was to evaluate the hypothesis that prenatal cocaine exposure would negatively affect newborn behavior. METHODS: A prospective observational study of term infants recruited from the low-risk nursery used a structured, standardized interview to obtain maternal data. Cocaine exposure was determined by radioimmunoassay of the infant's meconium stool. An examiner blinded to the infant's cocaine status administered the Brazelton Neonatal Behavioral Assessment Scales. RESULTS: The sample was composed of 23 exposed and 29 nonexposed infants. On six of the seven Brazelton Neonatal Behavioral Assessment Scale clusters, cocaine-exposed infants performed less well than control infants, with significant differences observed for autonomic stability. In addition, a dose-response relationship was suggested. Significant negative, within-group relationships were evident in the exposed group, indicating poorer performance with increasing meconium cocaine concentration for orientation (r = -.40) and regulation of state (r = -.40). Regression model testing of the influence of meconium cocaine concentration on neurobehavioral outcomes, after controlling for significant confounders, identified a significant independent, negative effect of meconium cocaine concentration on two clusters-motor and regulation of state. CONCLUSION: In otherwise healthy full-term infants, prenatal cocaine exposure identified by quantitative analysis of cocaine concentration in meconium had a significant, independent negative association with motor and regulation of state that remained after controlling for other significant confounders. A dose-response relationship was evident.

Adult↗
PubMed1995

Homeobox genes in the functioning of plant meristems.

The maize homebox gene knotted1 (kn1) is expressed in vegetative and floral meristems and is down-regulated at the site of primordia formation. kn1-related genes from maize and other species also show meristem-specific expression and offer additional tools for studying the activities of shoot meristems. Members of this gene family are expressed early in embryogenesis, providing molecular markers for meristem initiation. Ectopic expression of either kn1 or a related Arabidopsis gene, KNAT1, causes dramatic alterations in Arabidopsis and tobacco leaf morphology. Most significantly, meristems form on the leaf, producing small shoots. We discuss whether the phenotypes can be interpreted as changes in positional information or timing of determination.

Gene Expression Regulation, Plant↗
PubMed1995

Heterogeneity of vasomotor response to acetylcholine along the human coronary artery.

OBJECTIVES: In view of the segmental occurrence of coronary atherosclerosis, we postulated that acetylcholine may cause heterogeneous vasomotion, depending on the extent of vessel analyzed, criteria for change in vessel caliber and dose of drug administered. BACKGROUND: Previous studies have reported that acetylcholine causes constriction of atherosclerotic arteries. This dysfunction of endothelium-dependent dilation may be seen without angiographically detectable disease. METHODS: We developed algorithms to quantitate the dimensions of a single coronary artery over virtually its entire length during a control state and during graded doses of intracoronary acetylcholine. On the basis of triplicate control angiograms, the limit of detection of a change from control diameter was 0.31 mm (> or = 2 SD). RESULTS: Analysis of multiple segments (each 5.6 +/- 1.1 [mean +/- SD] mm) along a single coronary artery revealed a heterogeneous response to acetylcholine in 27 of 31 patients at the 10(-4) mol/liter dose and in 29 of 31 patients when responses at 10(-6), 10(-5) and 10(-4) mol/liter doses were combined; in this latter analysis, constriction and dilation in the same vessel occurred in 45% of the patients. With acetylcholine, most of 349 segments demonstrated no change, but the greatest frequency of vasoconstriction (24.6%) and vasodilation (6.9%) was seen at the 10(-4) mol/liter dose. Inducible vasomotion was observed as far distally as 7.3 cm from the site of acetylcholine infusion. CONCLUSIONS: Response to intracoronary acetylcholine with mild coronary disease is heterogeneous; disparate dimensional responses may occur in different segments of the same vessel. Inclusion of all analyzable regions of a coronary artery and the use of a reproducibility limit for quantitative angiography are optimal for assessment of segmental coronary vasomotion.

Acetylcholine↗
PubMed1995

Longterm methotrexate therapy in psoriatic arthritis: clinical and radiological outcome.

OBJECTIVE: To determine whether methotrexate (MTX) therapy for 24 months prevents progression of radiographic damage in psoriatic arthritis (PsA). METHODS: Patients who were given MTX during their attendance at the psoriatic arthritis clinic were enrolled in the study. Patients who had never had MTX and who were matched by damage, actively inflamed joints, sex, and disease duration were identified from the PsA database as controls. The outcome measure was increase in the number of damaged joints. RESULTS: The study population comprised 38 patients (16 F, 22 M) with a mean age of 44.6 years and disease duration of 11.4 years. Twenty-three patients continued therapy for 24 months. Clinical evaluation revealed that 45% of the patients had > or = 40% improvement in actively inflamed joint count at 6 and 24 months. Radiographs were available for 19 of the 23 patients who took MTX for 24 months, and they were compared to their respective controls. Radiographic damage scores at 24 months showed an increase in the damage score in 63% of the patients. Compared to the matched controls, there was no statistically significant difference in the progression in damage. CONCLUSION: Our results suggest that compared to other regimens, MTX conferred no advantage with respect to clinical response or longterm damage even after 24 months of therapy.

Adult↗
PubMed1995

Does injectable gold retard radiologic evidence of joint damage in psoriatic arthritis?

The aim of this investigation has been to assess whether gold therapy prevents radiologic progression of psoriatic arthritis (PsA) over a period of 2 y. Eighteen patients (11 males, 7 females, mean age 42 y, DD 6.5 y) who were initiated on intramuscular gold during their attendance at the Psoriatic Arthritis Clinic were studied. For each gold-treated patient, 2 matched control patients, who had never had gold therapy, were identified from the PsA database. The control patients were similar to the patient population in gender, age, disease duration, number of actively inflamed joints, radiologic score and other medications used, and were followed in the clinic for at least 24 months. Actively-inflamed joint count decreased by > or = 40% in 9 of 18 gold-treated patients at 12 months. Seven patients continued gold for 24 months, while 11 discontinued gold for either lack of efficacy (4) or side effects (7). A comparison of the change in radiographic evidence of damage in the peripheral joints between the 18 gold-treated patients and the 36 controls revealed that there was no statistical difference in disease progression. These results suggest that gold therapy does not prevent the progression of damage in patients with psoriatic arthritis.

Adult↗
PubMed1995

Parenchymal sparing surgery in patients with hereditary renal cell carcinoma.

The von Hippel-Lindau syndrome is the most well known cause of familial renal cancer. Because affected individuals with renal lesions can have complex, multisystem manifestations of von Hippel-Lindau disease, our renal management strategy has included parenchymal sparing surgery whenever possible. From May 1988 to January 1993, 20 patients with hereditary renal cell carcinoma (19 with von Hippel-Lindau disease and 1 with hereditary papillary renal cancer) underwent renal exploration with the intent of performing parenchymal sparing surgery. A total of 7 nephrectomies and 27 parenchymal sparing procedures was performed. Additional procedures performed included 2 bilateral adrenalectomies for pheochromocytomas, 1 resection of a renal vein thrombus and 1 resection of a pancreatic islet cell tumor. Renal atrophy occurred in 3 of 27 kidneys (11%) treated by parenchymal sparing surgery. In 8 kidneys of 7 patients new solid lesions developed and in 14 kidneys of 12 patients no new solid lesions developed during a mean followup of 26 months (range 6 to 60 months). The use of parenchymal sparing surgery in patients with familial forms of kidney cancer is based on a desire to maintain renal function as long as possible while reducing the risk of metastases. The potential advantages and disadvantages of more ablative surgical treatment requiring subsequent dialysis or transplantation in patients with existing or potential central nervous system, eye, pancreas and/or adrenal tumors must be weighed against the possibility of renal cancer metastases or recurrence when deciding on the use of parenchymal sparing surgery.

Adult↗
PubMed1994

A knotted1-like homeobox gene in Arabidopsis is expressed in the vegetative meristem and dramatically alters leaf morphology when overexpressed in transgenic plants.

The homeobox gene knotted1 (kn1) was first isolated by transposon tagging a dominant leaf mutant in maize. Related maize genes, isolated by virtue of sequence conservation within the homeobox, fall into two classes based on sequence similarity and expression patterns. Here, we report the characterization of two genes, KNAT1 and KNAT2 (for knotted-like from Arabidopsis thaliana) that were cloned from Arabidopsis using the kn1 homeobox as a heterologous probe. The homeodomains of KNAT1 and KNAT2 are very similar to the homeodomains of proteins encoded by class 1 maize genes, ranging from 78 to 95% amino acid identity. Overall, the deduced KNAT1 and KNAT2 proteins share amino acid identities of 53 and 40%, respectively, with the KN1 protein. Intron positions are also fairly well conserved among KNAT1, KNAT2, and kn1. Based on in situ hybridization analysis, the expression pattern of KNAT1 during vegetative development is similar to that of class 1 maize genes. In the shoot apex, KNAT1 transcript is localized primarily to the shoot apical meristem; down-regulation of expression occurs as leaf primordia are initiated. In contrast to the expression of class 1 maize genes in floral and inflorescence meristems, the expression of KNAT1 in the shoot meristem decreases during the floral transition and is restricted to the cortex of the inflorescence stem. Transgenic Arabidopsis plants carrying the KNAT1 cDNA and the kn1 cDNA fused to the cauliflower mosaic virus 35S promoter were generated. Misexpression of KNAT1 and kn1 resulted in highly abnormal leaf morphology that included severely lobed leaves. The expression pattern of KNAT1 in the shoot meristem combined with the results of transgenic overexpression experiments supports the hypothesis that class 1 kn1-like genes play a role in morphogenesis.

Amino Acid Sequence↗
PubMed1994

UNDULATORY SWIMMING: HOW TRAVELING WAVES ARE PRODUCED AND MODULATED IN SUNFISH (LEPOMIS GIBBOSUS)

We have developed an experimental procedure in which the in situ locomotor muscles of dead fishes can be electrically stimulated to generate swimming motions. This procedure gives the experimenter control of muscle activation and the mechanical properties of the body. Using pumpkinseed sunfish, Lepomis gibbosus, we investigated the mechanics of undulatory swimming by comparing the swimming kinematics of live sunfish with the kinematics of dead sunfish made to swim using electrical stimulation. In electrically stimulated sunfish, undulatory waves can be produced by alternating left­right contractions of either all the axial muscle or just the precaudal axial muscle. As judged by changes in swimming speed, most of the locomotor power is generated precaudally and transmitted to the caudal fin by way of the skin and axial skeleton. The form of the traveling undulatory wave ­ as measured by tail-beat amplitude, propulsive wavelength and maximal caudal curvature ­ can be modulated by experimental control of the body's passive stiffness, which is a property of the skin, connective tissue and axial skeleton.

Journal Article↗
PubMed1994

[Studies on the early serodiagnosis of leptospirosis by dot-ELISA].

Thirty serum samples of patients with early leptospirosis from whom cultures of leptospira were positive were tested by dot-enzyme linked immunosorbent assay (dot-ELISA) and microscopical agglutination test (MAT). The results showed that the positive rate of dot-ELISA (40%) was higher than that of MAT (13.3%). One-hundred and ninety-eight serum samples from patients with clinical diagnosis of early leptospirosis were tested by dot-ELISA, MAT and blood culture. The results showed that the positive rate of dot-ELISA (64.6%) was higher than that of blood culture (15.2%) and MAT (14.1%). The longer the time of the illness, the lower the positive rate of the blood culture. However, the positive rate of dot-ELISA was stable in different stages of the illness.

Agglutination Tests↗
PubMed1994

Physical properties and quantification of the ECT stimulus: I. Basic principles.

The physical properties of the electroconvulsive therapy (ECT) stimulus markedly affect both efficacy and side effects. We review basic principles in characterizing these physical properties and in quantifying the ECT stimulus. The topics discussed include the application of Ohm's law, alternative composite units of ECT dosage (energy and charge), the use of constant-current, constant-voltage, and constant-energy principles in ECT devices, the nature of current shunting in ECT and the determinants of impedance, the relations between impedance and seizure threshold, the seizure-eliciting efficiency of alternative stimulus waveforms and of stimulus parameter configurations, and the role of reactive components (capacitance and inductance) in the ECT circuit. New findings are also presented regarding several of these issues.

Electric Impedance↗
PubMed1994

[Cross transposition of expanded scalp flaps for the treatment of postburn cicatricial alopecia].

When the area of alopecia is very large, the normal scalp is not sufficient to cover the defect resulting from excision of the alopecia. From August 1987 to December 1989, 8 cases with large defect of scalp are repaired by means of expanded cross scalp flaps with good result. Among 8 cases, 7 are male and 1 female, and the largest area of alopecia is 300 cm2 and the smallest 112 cm2, with a mean of 191 cm2. Two expanders are buried under the galea aponeurotica on both sides of alopecia, and the scalp is expanded. The central part of the expanded scalp is chosen to form the "major flap", the lateral part of the expanded scalp to form the "adjuvant flap". Two flaps are then crossed and the defect is repaired. The method of scalp expansion and "axial flap" is used in marginal alopecia. An expander is buried under the galea aponeurotica on each side of the alopecia. After the scalp is expanded, the central part of the expanded scalp is chosen to from "axial flap" with the pedicle consisting of superficial temporal artery or occipital artery and the lateral part of the expanded scalp to form the "adjuvant flap". Then two flaps are transposed and the defect is thus repaired.

Adolescent↗
PubMed1994

Cerebellar infarction. Analysis of 22 cases.

Twenty-two cases of cerebellar infarction were diagnosed by clinical findings, computerized tomography (CT), magnetic resonance image (MRI) and autopsy. Most of the infarctions occurred in the territory of the posterior inferior cerebellar artery (18/22). The most common and earliest symptoms were dizziness or vertigo (19/22), which occurred repeatedly and were accompanied by nausea and vomiting. The symptoms and signs of cerebellar lesion such as unsteady gait, limb and/or trunk ataxia, dysarthria were also the main clinical manifestations. However, in a number of patients there were no cerebellar symptoms or signs (9/22). Rapid deterioration of consciousness suggested acute compression of the brainstem, where the prognosis would be poor. CT scan made it possible to diagnose cerebellar infarction in the patients. But CT is not a satisfactory instrument in identifying this disease. MRI without bony artifacts from the posterior fossa has much higher resolution and renders the infarction to be visualized earlier. It may be regarded as the most ideal instrument in diagnosing this disease.

Adult↗
PubMed1993

Three-dimensional structure of tyrosine phenol-lyase.

Tyrosine phenol-lyase (EC 4.1.99.2) from Citrobacter freundii has been cloned and the primary sequence deduced from the DNA sequence. From the BrCN digest of the NaBH4-reduced holoenzyme, five peptides were purified and sequenced. The amino acid sequences of the peptides agreed with the corresponding parts of the tyrosine phenol-lyase sequence obtained from the gene structure. K257 is the pyridoxal 5'-phosphate binding residue. Assisted by the sequence data, the crystal structure of apotyrosine phenol-lyase, a pyridoxal 5'-phosphate-dependent enzyme, has been refined to an R-factor of 16.2% at 2.3-A resolution using synchrotron radiation diffraction data. The tetrameric molecule has 222 symmetry, with one of the axes coincident with the crystallographic 2-fold symmetry axis of the crystal which belongs to the space group P2(1)2(1)2 with a = 76.0 A, b = 138.3 A, and c = 93.5 A. Each subunit comprises 14 alpha-helices and 16 beta-strands, which fold into a small and a large domain. The coenzyme-binding lysine residue is located at the interface between the large and small domains of one subunit and the large domain of a crystallographically related subunit. The fold of the large, pyridoxal 5'-phosphate binding domain and the location of the active site are similar to that found in aminotransferases. Most of the residues which participate in binding of pyridoxal 5'-phosphate in aminotransferases are conserved in the structure of tyrosine phenol-lyase. Two dimers of tyrosine phenol-lyase, each of which has a domain architecture similar to that found in aspartate aminotransferases, are bound together through a hydrophobic cluster in the center of the molecule and intertwined N-terminal arms.

Amino Acid Sequence↗