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Biomedical subjects

J Long

Publications and source records attributed to J Long.

At least 91 records · Page 5Linked to original sources
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↗
PubMed1993

Lesions of the hippocampus enhance or depress humoral immunity in rats.

The effect on the humoral immune response in rats by bilaterally destroying cell bodies in the hippocampus with kainic acid or by electrolytic lesion was studied. After 3 days a humoral immune response was evoked by injecting 1 ml of 10% sheep red blood cells. Five days later, the haemolysin content (MC50) was measured. Chemical destruction of pyramidal cell bodies in CA2 and CA3 significantly increased humoral immunity as measured by HC50, but larger chemical lesions that also included CA1 did not. Electrical destruction of cell bodies and axonal pathways in CA2 and CA3 did not significantly affect HC50. These results suggest that different areas of the hippocampus can stimulate or inhibit humoral immunity.

Animals↗
PubMed1993

Costs associated with office visits for diarrhea in infants and toddlers.

We determined costs associated with diarrhea in a < 36-month-old ambulatory population. Children with acute diarrhea were enrolled during the rotavirus season at three centers. Questionnaires to assess costs of both medical and nonmedical factors were administered at the enrollment visit and 1 week later. Office computer records were reviewed to identify all visits by children with diarrhea during 1 year. Fifty-one patients were enrolled. The average cost per episode of diarrhea was $289, which included: $144, missed work; $57, office visits; $23, laboratory tests; $21, medications; $18, changed diet/oral rehydration solutions; $15, travel; $7, extra diapers; and $6, extra child care. During 1 year diarrhea accounted for 4% of all visits and 10% of visits among those < 36 months old. The annual cost at the three centers was $346,000, which extrapolates to $0.6 to $1.0 billion for the United States. Twenty-one percent of this cost was attributable to rotavirus diarrhea. We conclude that outpatient care for pediatric diarrhea is a major health care cost in the United States.

Child, Preschool↗
PubMed1993

DRD2 dopamine receptor genotype, linkage disequilibrium, and alcoholism in American Indians and other populations.

We defined interpopulation differences in the frequency of the dopamine D2 receptor DRD2/Taq1 A1 allele, which has previously been associated with alcoholism. Frequencies of the A1 allele in unrelated subjects were 0.18 to 0.20 (se = 0.02 to 0.03) in several Caucasian populations previously assessed, 0.38 (+/- 0.05) in American Blacks (n = 44), 0.63 (+/- 0.07) in Jemez Pueblo Indians (n = 23), and 0.80 (+/- 0.04) in Cheyenne Indians (n = 52). The existence of large interpopulation differences in the frequency of the Taq1 alleles suggests that associations to disease status could readily be generated or masked if disease and control groups were uneven in ethnic composition. To address the possibility that the 4-fold higher frequency of the A1 allele in Cheyenne Indians was related to an increased vulnerability to alcoholism in that population, 47 Cheyenne Indians were psychiatrically interviewed and blind-rated. However, there was no significant difference between interviewed controls (0.73 +/- 0.06, n = 24), subjects with alcoholism and/or drug abuse (0.74 +/- 0.06, n = 23) and noninterviewed population controls (0.87 +/- 0.05, n = 20). Legitimate association of the DRD2/Taq1 allele to alcoholism would presumably require it to be in linkage disequilibrium (nonrandom association) with a functional mutation at DRD2 or elsewhere. The level of disequilibrium would vary between populations and could place an upper bound on the strength of an association.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1993

Shade selection and laboratory communication.

This article reviews some of the factors involved in shade selection for prosthetic teeth and suggests simple techniques for accurately transmitting information about the desired color to the laboratory technician.

Color↗
PubMed1992

The significance of choroid plexus cysts in fetuses at 18-20 weeks. An indication for amniocentesis?

Over a period of 25 months, all antenatal patients were offered a detailed ultrasound scan at 18-20 weeks' gestation. The lateral cerebral ventricles were scanned for the presence of choroid plexus cysts. Fifty-one patients found to have choroid plexus cysts were offered amniocentesis to exclude chromosomal abnormalities. One pregnancy, in which the only abnormality found was bilateral choroid plexus cysts, was terminated after trisomy 18 was detected on amniocentesis at 19 weeks. The other 50 pregnancies had normal fetal outcomes. The significance of the isolated finding of choroid plexus cysts is reviewed.

Adult↗
PubMed1992

Comparison of the fracture strengths of ceramometal crowns versus several all-ceramic crowns.

Fracture resistance to forces applied to the incisal edges of four types of anterior crowns was tested. Ceramometal crowns fractured at significantly higher values (720 psi) than the all-ceramic crowns (approximately 360 psi). No significant difference was found among the fracture values of the Dicor crowns, the aluminous porcelain jackets, and the crowns fabricated from Dicor veneered with aluminous body and incisal porcelain.

Aluminum Oxide↗
PubMed1992

Applications and limitations of vitreoretinal biopsy techniques in intraocular large cell lymphoma.

The cases of 4 patients with clinical signs of intraocular large cell lymphoma are described. Initial cytopathologic examination of vitrectomy specimens failed to establish the malignant character of the vitreous infiltrates. Three of the four patients eventually developed solid central nervous system tumors, intracranial biopsy samples of which revealed large cell lymphoma, 13 months to 42 months after initial examination. In one patient, transscleral retinochoroidal biopsy confirmed the diagnosis at the same time as negative vitreous cytologic examination. Results of cytopathologic examination alone of vitreous biopsy specimens may not be sufficient to make a diagnosis in certain cases of large cell lymphoma that are subsequently documented by CNS biopsy. Careful attention should be paid to the handling, processing, and interpretation of vitrectomy specimens from patients suspected of having intraocular large cell lymphoma. Consideration should be given to immunocytologic staining and interpretation by centers that are highly experienced in vitreous cytopathology.

Biopsy↗
PubMed1991

[Cerebellar infarction and its assistant examination].

The clinical manifestations of cerebellar infarction are often non-particular and it is difficult to make such a diagnosis clinically. Diagnosis was based on pathology previously. Most of the cases were overlooked while still living and the true morbidity was not known. CT scan has made the diagnosis of this disease possible clinically in some patients, but CT is still not an ideal instrument for diagnosing this disease because of the interference by bony artifacts of posterior fossa. The advent of MRI made it possible to distinguish cerebellar infarction safely and easily. It is not the most powerful tool for diagnosing this disease. The authors reported 15 cases of cerebellar infarction diagnosed by clinical manifestation, neuroimages and pathology and pointed out that further knowledge of this disease is needed.

Adult↗
PubMed1990

[Non-operation management of 12 cases with brain abscess demonstrated by CT scan].

This paper reported 12 cases with brain abscess demonstrated by CT scan. Using antibiotic management without surgical intervention, in 10 cases the curative effects were satisfactory. The paper indicated that CT scan was very useful in prompt and correct diagnosis of brain abscess and with sequential CT scan medical therapy was feasible. It is significant in treatment of brain abscess especially for the patients who have a poor general condition, have the brain abscess located in important functional area or have multiple abscesses so that the operation is difficult for them.

Adolescent↗