Search PubMed⌕ Search

Biomedical subjects

J Tan

Publications and source records attributed to J Tan.

At least 271 records · Page 15Linked to original sources
PubMed1991

[The RFLP of LDR152/PstI in the Chinese and its application to linkage analysis in a myotonic dystrophy family].

Myotonic dystrophy (DM) is inherited as an autosomal dominant trait and is characterized by variable expressivity and late age-of-onset. In the present paper, the DNA from 61 normal individuals and a DM family with 15 members of 4 generations were collected and digested with PstI, then hybridized with the LDR152 (D19S19). The results showed that the alleles for the PstI polymorphism were 19 and 11kb in size (gene frequencies were 0.4344 and 0.5656 respectively, which are obviously different from the previous data reported). In this DM family, the carriers who had lived most of their life without knowing that they had been infected with the disease were detected by the LDR152 and the estimation of DM risk on at-risk-individuals was also calculated.

Chromosomes, Human, Pair 19↗
PubMed1990

New type of X-linked progressive muscular dystrophy involving shoulder girdle and back.

A new type of X-linked muscular dystrophy is described in a family in which 7 men had boyhood onset of progressive dystrophy involving muscles of the shoulder and back but not the calves or face. The scapula-back muscles are affected, but the calf muscles are normal. All patients are still able to walk. The oldest patient is now 37 years old. The muscular dystrophy has been specified by electromyography, pathologic tissue microscopic examination, electron microscopic study, and elevated CK. This type of muscular dystrophy has not been reported previously.

Adolescent↗
PubMed1990

Histopathology of cocaine hepatotoxicity. Report of four patients.

Although cocaine is believed to be hepatotoxic for humans, the hepatic histopathology has been reported in only 1 patient. That patient had zone-1 necrosis. We have encountered 4 patients with liver injury secondary to cocaine use, 1 of whom died. The biopsies from two patients showed well-demarcated zone-3 necrosis identical to that seen with acetaminophen toxicity. The patient who died had necrosis of almost all hepatocytes as found at biopsy and autopsy. Biopsy was performed on another patient after resolution of the illness, and showed hyperplastic endoplastic reticulum but no necrosis. All patients had mild large- and small-droplet steatosis in surviving hepatocytes. Inflammation was mild. Drug screenings performed on all patients showed the presence of a cocaine metabolite and the absence of acetaminophen, alcohol, and other potential toxins. Patients typically had early marked increase and rapid decrease of serum aminotransferases, mild-to-moderate increase in prothrombin time, myoglobinuria, and moderate azotemia. The predominant pattern of zone-3 necrosis is similar to that reported of mice given cocaine.

Adult↗
PubMed1990

Development of a novel series of (2-quinolinylmethoxy)phenyl-containing compounds as high-affinity leukotriene receptor antagonists. 1. Initial structure-activity relationships.

This series of reports describes the development of orally active, highly potent, specific antagonists of the peptidoleukotrienes containing a (2-quinolinylmethoxy)phenyl moiety. Described in this first report are the structure-activity relationships that led to a more than a 20-fold improvement of the potency and selectivity of the initial chemical lead (RG 5901). From this series of compounds, RG 7152 (16) was identified and selected for further evaluation in the clinic as an antiasthmatic agent. Compound 16 competitively inhibits [3H]LTD4 binding to membranes from guinea pig lung (Ki = 38 +/- 6 nM) and the spasmogenic activity of LTC4, LTD4, and LTE4 in parenchymal lung strips from guinea pigs. Unlike the original lead (RG 5901), compound 16 does not inhibit 5-lipoxygenase from guinea pig PMNs. Following oral administration to guinea pigs, 16 blocks LTD4-induced dermal permeability (ED50 = 6.9 mg/kg), LTD4-induced bronchoconstriction (ED50 = 1.1 mg/kg), antigen-induced bronchoconstriction (ED50 = 2.5 mg/kg), and anaphylactic-induced mortality (ED50 = 16 mg/kg). These studies on structure-activity relationships indicate that there is a requirement for an acidic function and the presence of the (2-quinolinylmethoxy)phenyl moiety in a specific geometric arrangement.

Animals↗
PubMed1990

[The role of hemorheologic changes in the pathogenesis of acute hemorrhagic necrotizing pancreatitis].

The hemorheologic alterations were studied in experimental acute hemorrhagic necrotizing pancreatitis (AHNP) which was induced by injection of 5% sodium taurocholate into the main pancreatic duct. The results showed that during the early stage of AHNP, all of hemorheologic parameters were significantly elevated, and continually increased at the rest intervals. The authors suggested that the blood viscosity and hematocrit increase, red blood cells tend to aggregate, and erythrocyte deformation decrease are the causation of pancreatic microcirculatory disturbances and promoting pancreatic progressive necrosis. After using low molecular dextran and Salvia miltiorrhizae, the hemorheologic alterations in AHNP were recovered, and the histologic observation improved. Our data indicate the hemorheologic disturbances is one of the key factors in the pathogenesis of AHNP.

Acute Disease↗
PubMed1990

Pulmonary artery involvement in aorto-arteritis. An analysis of DSA.

Angiographic features of the pulmonary artery were studied in 24 patients with aortoarteritis (Takayasu's arteritis) by digital subtraction angiography. The pulmonary artery involvement was found in nine cases (37.5%). The right side was involved in eight and the left side in five cases. The right pulmonary artery was involved in two cases, the lobar artery in six, the segmental artery in six, and subsegmental as well as peripheral branches in four. The angiographic features were stenosis and/or occlusion as were the changes of the systemic arteries in aorto-arteritis. The aorta and its main branches were involved in all nine patients, but the severity of pulmonary vascular changes was not always related to the systemic vascular changes. Bronchial angiography demonstrated enlarged and tortuous bronchial arteries in four cases. Lung ECT revealed abnormalities in four cases.

Adolescent↗
PubMed1990

The embryonal development of the human eye photoreceptors.

The development of the photoreceptors of human embryos and fetuses dating from 7 weeks to term were studied. The outer segments of rods and cones began to form at the seventh month. The arrangement of the newly formed discs were not regular, but at term they were arranged parallel to each other and perpendicular to the long axes of the outer segments. At the 9th month, no phagosome containing discs was seen in the pigment epithelial cells, but they were discerned in those of the term fetuses.

Cilia↗
PubMed1990

[Effect of bronchoalveolar lavage fluid on silica-induced alveolitis in rats].

An experimental silicosis model was produced in rats by intratracheal instillation of 25 mg silica dioxide normal saline. Animals were killed at 1, 3, 7, 14, 45 days after treatment, for cytological, enzyme cytochemical and biochemical analyses of the bronchoalveolar lavage fluid. The results showed that the number of polymorphonuclear cells and alveolar macrophages (AMs) increased continuously. The total amount of protein and activities of LDH and AcP in the lavage fluid were elevated, while the activities of LDH, SDH and AcP demonstrated by enzyme cytochemical staining in AMs were lowered. The survival rate of AMs decreased and foamy AMs appeared, these changes reflected the main characteristics of silica-induced alveolitis. We conclude that silica-induced alveolitis is not only the essential pathological characteristics of early pulmonary reaction to silica, but also plays a crucial role in the pathogenesis of silicotic fibrosis.

Animals↗
PubMed1989

Representations of ocular rotations in the cerebellar flocculus of the rabbit.

The climbing fibres (CFs) of the rabbit flocculus that respond in a speed- and direction-selective manner to retinal image slip produced by eye rotations can be divided into three classes on the basis of the orientation of the rotation axis associated with their greatest modulation (the preferred axis). The similarity of the orientations of these axes to those of the eye rotation axes of the extraocular muscles suggests that a simple geometrical correspondence may exist between the eye rotation associated with the preferred axis of a given class of CFs and the eye rotation produced by activation of the Purkinje cells upon which that class of CFs synapse. To pursue this possibility, the axes of the eye rotations evoked by electrical microstimulation of the alert rabbit's flocculus were determined simultaneously for both eyes in three dimensions using two orthogonal search coils on each eye. A limited number of slow eye movement response patterns were found, and of these, two predominated. The most common response was a counterclockwise (CCW) rotation of the ipsilateral (left) eye around an axis close to the horizontal plane and at about 140 degrees posterior to the nose. The other predominant response was abduction of the ipsilateral eye. These two response patterns, together with the smaller conjugate components for the contralateral eye, are consonant with the orientations of the preferred CF axes. In addition, a clear CCW rotation of the contralateral (right) eye about its 135 degrees axis was also evoked from some stimulation sites. This response, which occurred either alone or as a component of an upward rotation about the nasal-occipital (roll) axis, is at variance with the orientations of the preferred CF axis. However, the latencies of the CCW contralateral 135 degrees component (80-140 ms) were greater than those of the CW contralateral 45 degrees component, the CCW ipsilateral 135 degrees component and the ipsilateral abduction component (8-48 ms). These latency differences may distinguish stimulation of Purkinje cells from stimulation of other neurones.

Action Potentials↗
PubMed1989

Differential effects of a series of hydroxamic acid derivatives on 5-lipoxygenase and cyclooxygenase from neutrophils and 12-lipoxygenase from platelets and their in vivo effects on inflammation and anaphylaxis.

The synthesis of a series of novel substituted hydroxamates has been described along with their profile of inhibitory activity against 5-lipoxygenase, 12-lipoxygenase, and cyclooxygenase enzymes. The structure--activity relationship suggests that future molecules could be designed to specifically inhibit one or more of these enzymes since there were definite differences in structure--activity relationships for these different enzymes. A representative number of these compounds have been tested in vivo and found to possess potent oral activity in a systemic anaphylaxis model mediated by leukotrienes and topical activity in an arachidonic acid induced inflammation model. One of these molecules, compound 20, demonstrated that a leukotriene antagonist pharmacophore can be modified such that it contains both antagonist activity and 5-lipoxygenase inhibitory activity.

Anaphylaxis↗
PubMed1988

Balanced X;15 translocation 46,X,t(X;15)(q21;q23) associated with primary amenorrhea.

Cytogenetic studies on a woman with primary amenorrhea showed an X;15 translocation, karyotype 46,X,t(X;15)(q21;q23). Fifteen percent of the buccal cells showed a normal-sized sex chromatin body. The normal X chromosome was uniformly inactivated. Many balanced X;15 translocations have been reported; however, breakpoints in our patient differ from those reported previously. This case also supports earlier evidence that ovarian development fails when the breakpoint of the X chromosome is in the region X q13-q25 or q13-q27.

Adult↗
PubMed1988

The human androgen receptor: complementary deoxyribonucleic acid cloning, sequence analysis and gene expression in prostate.

Androgenic hormones mediate their effects on male sex differentiation and development through a high affinity receptor protein. We report here cloning of the complete coding sequence of the human androgen receptor (hAR). By sequence homology hAR is a member of the nuclear receptor family, with closest sequence identity to the progesterone, mineralocorticoid, and glucocorticoid receptors. Regions of highest homology include the DNA-binding domain and a small region within the hydrophobic ligand-binding domain. Comparison of the deduced 919 amino acid sequence of hAR (98,999 mol wt) to the 902 amino acid sequence of rat AR (98,227 mol wt) reveals identical sequences in the DNA- and hormone-binding domains, with an overall homology of 85%. In human prostate, the major androgen receptor mRNA species is 10 kilobases while a less abundant mRNA is approximately 7 kilobases. Rabbit polyclonal antibodies were raised against a synthetic peptide from the N-terminal region of hAR. Immunocytochemical analysis of human prostate tissue demonstrated that AR is localized predominantly in nuclei of glandular epithelial cells.

Amino Acid Sequence↗
PubMed1988

Blinded comparison of cefuroxime to cefaclor for lower respiratory tract infections.

Cefuroxime axetil was compared with cefaclor for the therapy for lower respiratory tract infections. Sixty-one patients were randomized to receive the following drug dosages: (1) cefuroxime axetil, 250 mg orally every 12 hours (21 patients); (2) cefuroxime axetil, 500 mg orally every 12 hours (21 patients); and (3) cefaclor, 500 mg orally every eight hours (19 patients). Of these 61 patients, 80% were male, with a mean age of 59.5 years; 56% had acute pneumonia, and the remainder had an acute bronchitis. Causative pathogens included typical respiratory tract pathogens. Overall, 23 of 27 patients with bronchitis were clinically cured at the end of therapy. Thirty-one of 34 pneumonias were clinically cured or improved at the end of therapy; the three pneumonia treatment failures occurred in the lower dose cefuroxime (n = 2) and cefaclor (n = 1) treatment groups. Overall, bacteriologic cure occurred in 86% of patients treated with 500 mg of cefuroxime axetil compared with 60% of cefaclor-treated patients. Adverse clinical effects were uncommon. From this study, it was concluded that cefuroxime given every 12 hours is at least as clinically efficacious as cefaclor; it is a new oral cephalosporin with pharmacologic and bacterial spectrum advantages over many older agents.

Acute Disease↗