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Biomedical subjects

S Ma

Publications and source records attributed to S Ma.

At least 181 records · Page 10Linked to original sources
PubMed1994

[Molecular cytogenetic study of Turner's syndrome with the 45, X/46,X,r(?) karyotype].

Two small marker chromosomes were identified as X-derived ring chromosomes by using the high-resolution banding technique and in situ hybridization with a radioactively labelled human X-chromosome-specific satellite DNA probe. This procedure clearly determined the origin of the marker chromosome, which had been impossible using conventional cytogenetic techniques. The clinical significance of this work is briefly discussed.

Adolescent↗
PubMed1994

[Effects of phenytoin and cabamazepine on sex hormones in male patients with epilepsy: a controlled study].

We measured the levels of estradiol (E2), total testosterone (TT) and free testosterone (FT) in 24 male patients with epilepsy receiving phenytoin (DPH), 21 male patients with epilepsy receiving cabamazepine (CBZ), 23 male epileptics receiving no treatment, and in 10 healthy age-matched male controls. The FT and TT levels of the DPH group were significantly lower and higher than those of the normal control group, respectively. The E2, FT and TT of the CBZ group were all lower than those of the normal controls. The results showed the difference between DPH and CBZ in the mechanism of affecting the levels of sex hormones; therefore, the treatments should not be the same.

Adolescent↗
PubMed1993

Crystal structures of two cyclic pseudopentapeptides containing psi[CH2S] and psi[CH2SO] backbone surrogates.

The solid state conformations of cyclo [Gly-Pro psi[CH2S] Gly-D-Phe-Pro] and cyclo [Gly-Pro psi[CH2-(S)-SO]Gly-D-Phe-Pro] have been characterized by X-ray diffraction analysis. Crystals of the sulfide trihydrate are orthorhombic, P2(1)2(1)2(1), with a = 10.156(3) A, b = 11.704(3) A, c = 21.913(4) A, and Z = 4. Crystals of the sulfoxide are monoclinic, P2(1) with a = 10.662(1) A, b = 8.552(3) A, c = 12.947(2) A, beta = 94.28(2), and Z = 2. Unlike their all-amide parent, which adopts an all-trans backbone conformation and a type II beta-turn encompassing Gly-Pro-Gly-D-Phe, both of these peptides contain a cis Gly1-Pro2 bond and form a novel turn structure, i.e., a type II' beta-turn consisting of Gly-D-Phe-Pro-Gly. The turn structure in each of these peptides is stabilized by an intramolecular H bond between the carbonyl oxygen of Gly1 and the amide proton of D-Phe4. In the cyclic sulfoxide, the sulfinyl group is not involved in H bonding despite its strong potential as a hydrogen-bond acceptor. The crystal structure made it possible to establish the absolute configuration of the sulfinyl group in this peptide. The two crystal structures also helped identify a type II' beta-turn in the DMSO-d6 solution conformers of these peptides.

Amino Acid Sequence↗
PubMed1993

Iatrogenic bilateral femoral mycotic aneurysms: a case report following burns.

Haemodynamic monitoring is important in severely burned patients and repeated catheterization of the arteries of these victims seems to be inevitable. We present a 46-year-old female with 54 per cent TBSA burns who suffered from bilateral femoral mycotic aneurysms due to repeated arterial punctures.

Aneurysm, Infected↗
PubMed1993

Hypotensive and bradycardiac responses to reflex sympathetic inhibition produced by nitroglycerin in rats with sinoaortic deafferentation.

Nitroglycerin (NTG) may cause paradoxical bradycardia and occasional life-threatening hypotension. The mechanism is unclear. In this study, we compared the cardiovascular responses of sodium nitroprusside (SNP) with that of NTG in rats with sinoaortic deafferentation (SAD). Intravenous (i.v.) injection of SNP and NTG produced dose-dependent decreases in mean arterial pressure (MAP). SNP was more effective than NTG in increasing heart rate (HR). After SAD, tachycardiac responses to i.v. SNP were abolished, but i.v. NTG caused bradycardia. SAD enhanced the hypotensive responses of both NTG or SNP after i.v. administration. The bradycardic and hypotensive effects of NTG were attenuated by either bilateral vagotomy or intracisternal (i.c.) pretreatment with 20 nmol rauwolscine, but the responses were not altered by i.v. atropine methylbromide (M-atropine), 0.6 mumol. In contrast, cardiovascular responses to i.v. SNP after SAD were not altered by these pretreatments. Tachycardiac responses to intracerebroventricular (i.c.v.) injection of NTG were reduced by SAD, but SAD did not alter bradycardic responses to i.c. injection of NTG. These results suggest that NTG induces inhibitory reflexes that may contribute to its complex cardiovascular responses in rats. The drug may stimulate peripheral sensory receptors with vagal afferents to the medulla, which then triggers an alpha 2-adrenoceptor-mediated sympathoinhibition.

Animals↗
PubMed1993

[Severe acute pancreatitis and ARDS].

A survey was done in 28 cases of severe acute pancreatitis with main interest on their respiratory appearance. It was noticed that at the early stage of the disease process the patients did develop some degree respiratory disorders but they were mild in severity. Only after successful resuscitation of septic shock and its accompanying diffuse body tissue injury, then followed severe clinical respiratory failure symptom which is now known as acute respiratory distress syndrome (ARDS). ARDS in this disease usually had two phases, one immediately after the early resuscitation, which was usually 2-3 days after the disease and followed by a period of recovery of respiratory syndrome and the second ARDS phase with fulminante clinical respiratory failure usually developed 10-14 days after the disease. The reburning phase of ARDS, was clinically very serious and went together with pulmonary infections in all cases. A discussion was made in this retrospective study about all the clinical findings, the risk factors and their reasonable treatments.

Acute Disease↗
PubMed1993

[Cytogenetic and molecular genetic study on a female with complex translocation of t(Y;15) and t(14;21)].

A 27-year-old female having a baby with Down's syndrome was found to have a translocation t(14;21) and an acrocentric marker chromosome 15. The short arm of the marker was darkly stained in both G- and C-banded preparations, and had the normal Ag-NOR, but showed a homogeneously stained region in the distal part of the marker. By means of QM staining, the variant was found fluorescent, and Y-body like was found in about 9% interphase nuclei, which suggested that there might exist Y chromosome material in genomic DNA of proband. Dot blot hybridization using DNA probe pY3.4 derived from the heterochromatic region on the long arm of Y chromosome demonstrated that the proband carried Y chromosome material in her genome. Further, by in situ hybridization with the same probe, it showed that the variant of the marker had specific autoradiographic silver grains. So, the karyotype of the proband indicated that the combination of conventional banding analysis with chromosome-specific probe was of great significance in studying the micro-aberration of human chromosome.

Adult↗
PubMed1993

[Rapid screening of the Duchenne muscular dystrophy gene deletion by two multiplex PCR].

Duchenne muscular dystrophy (DMD) is one of the most common lethal X-linked disorders. Partial intragenic deletions account for up to 60% of DMD deletions, and approximately one-third of all cases arise via new mutations. In this paper, two sets of primers were used for two multiplex PCR screenings of DMD gene deletions. The first set consists of 5 pairs of primers which amplify 5 exons with higher deletion frequencies, and the second set includes other 4 pairs of primers. Fifty-one DMD samples were screened by the first set, and then those not found to have deletions were screened by the second set. In total, 25 deletions were identified in the Fifty-one DMD samples: That is, about 49% of all cases studied were found to have deletions.

Base Sequence↗
PubMed1993

Conformations of psi [CH2NH] pseudopeptides. Cyclo[Gly-Pro psi [CH2NH]Gly-D-Phe-Pro]-TFA and cyclo[Gly-Pro psi [CH2NH]Gly-D-Phe-Pro].

The cyclic pseudopentapeptide cyclo[Gly-Pro psi [CH2NH]Gly-D-Phe-Pro] and its TFA salt were synthesized by solution methods, and their conformations were studied by NMR spectroscopy in both DMSO-d6 and CDCl3. While intramolecular hydrogen bonding is observed with some conformers, the nature of the solvent and the presence of TFA affects the relative structural rigidities of the compounds. No evidence was found for the psi [CH2NH] or psi [CH2NH2+] units acting as H donors in this series.

Amino Acid Sequence↗
PubMed1992

Initiation of bone regeneration in adult baboons by osteogenin, a bone morphogenetic protein.

Osteogenin, and related bone morphogenetic proteins, induce endochondral bone differentiation through a cascade of events which include formation of cartilage, hypertrophy and calcification of the cartilage, vascular invasion, differentiation of osteoblasts, and formation of bone. These events have been studied in a postnatal model of bone development in rodents. Information concerning the morphogenetic potential of osteogenin in primates is a prerequisite for potential clinical application in man. The efficacy of allogeneic osteogenin in primates was investigated in both extraskeletal and skeletal sites in 19-Chacma baboons (Papio ursinus). Osteogenin was isolated from demineralized baboon bone matrix and purified by chromatography on heparin-Sepharose, hydroxyapatite, and Sephacryl S-200. Protein fractions with a molecular mass range of 26-42 kDa induced cartilage and bone differentiation in the subcutaneous space of rats. Final purification to homogeneity was obtained by electroendosmotic elution from a preparative sodium dodecyl sulphate (SDS) polyacrylamide gel, resulting in a single band on a SDS-polyacrylamide gel with an apparent molecular mass of 30-34 kDa, with biological activity in rats. The osteoinductive potential of osteogenin in primates was tested first in intramuscular sites in baboons and found to be active. The bone regeneration potential was investigated in nonhealing calvarial defects surgically prepared in adult male baboons. Baboon osteogenin induced complete regeneration of the cranial wound. These findings in adult primates establish a primary role for osteogenin in initiation and promotion of osteogenesis, and imply a potential therapeutic application based on cell biology of extracellular matrix-cell interactions.

Animals↗
PubMed1992

The critical role of geometry of porous hydroxyapatite delivery system in induction of bone by osteogenin, a bone morphogenetic protein.

The collagenous extracellular matrix of bone obtained after dissociative extraction with 4 M guanidine-HCl is an optimal substratum for bone induction by osteogenin, a bone morphogenetic protein. As a proteinaceous substratum, this matrix and other collagen-based materials may be immunogenic. Thus, the search and discovery of a non-immunogenic substratum is a necessary prerequisite for the therapeutic application of the principle of bone induction to skeletal repair. Bovine osteogenin, purified greater than 50,000-fold and with an apparent molecular mass of 28-42 kilodaltons, was delivered into nonresorbable porous hydroxyapatite in granular and disc configuration. A total of 328 preparations were bioassayed for osteogenic activity by subcutaneous implantation into 164 Long-Evans rats. Specimens were harvested at day 7, 11 and 21 after implantation and subjected to alkaline phosphatase activity determination and histologic analysis. Osteogenin combined with discs of porous hydroxyapatite induced in vivo differentiation of the osteogenic phenotype in mesenchymal cells invading the three-dimensional porous space of the inorganic substratum. The geometry of the substratum had a profound influence on bone induction, since the expression of the osteogenic phenotype was solely confined in porous hydroxyapatite with disc configuration. Osteogenin did not induce bone differentiation when combined with granules of porous hydroxyapatite with identical pore dimensions. The finding that the biological activity of osteogenin can be restored and delivered by a substratum with defined geometry other than the insoluble collagenous matrix may form the basis of the potential therapeutic application of bone morphogenetic proteins.

Animals↗
PubMed1992

Central noradrenergic activity and the cardiovascular effects of nitroglycerin and amyl nitrate.

Intracerebroventricular and i.v. administration of nitroglycerin in anesthetized Sprague-Dawley rats produced dose-dependent decreases in mean arterial pressure and increases in heart rate, but intracisternal injection of the drug induced hypotension and bradycardia. Hypotensive responses to intracisternal injection of nitroglycerin showed that the compound was two to three times more potent than by i.v. administration (six times when comparing the area under the curve). Intravenous sodium nitroprusside produced dose-dependent hypotensive and tachycardiac effects, but minimal responses were induced by i.c.v. and intracisternal injection. Central pretreatment with either yohimbine or rauwolscine antagonized hypotensive responses to i.c.v. and i.v. nitroglycerin, but did not alter the depressor responses induced by i.v. sodium nitroprusside. Tachycardiac responses to i.c.v. nitroglycerin are greater than the responses induced by i.v. administration. Inhalation of amyl nitrite produced marked hypotensive responses, with the dose-response curves being shifted to the right by i.c.v. pretreatment with rauwolscine, but not by i.v. pretreatment. The concentrations of 3,4-dihydroxyphenylglycol and 3-methoxy-4-hydroxyphenylglycol in cerebrospinal fluid were increased by i.v., i.c.v., and intracisternal administration of nitroglycerin, but were not altered by i.v. sodium nitroprusside. The concentrations of dihydroxyphenylacetic acid were elevated by i.v. and i.c.v. injection of nitroglycerin. Results suggest that nitroglycerin stimulates central noradrenergic activity, which may be involved in the component of hypotensive effects of the drug. Reflex tachycardiac responses to nitroglycerin may be further complicated by forebrain stimulation and medulla-mediated bradycardia. Sodium nitroprusside did not demonstrate central activity.

Animals↗
PubMed1992

[The effects of nitroglycerin on refractory congestive heart failure by intravenous infusion].

Noninvasive hemodynamic and clinical studies were carried out in 24 patients with congestive heart failure refractory to digitalis, diuretics and vasodilators. Nitroglycerin was given by intravenous infusion for 5-7 days. The results showed that the symptoms, signs and hemodynamic parameters were markedly improved. The overall clinical effective rate was 96% and no serious side effect was noted.

Adult↗
PubMed1992

Further studies on central actions of nitroglycerin and lack of evidence for nitroglycerin interacting on [3H]clonidine binding sites in cortex membranes.

Decerebration and transection of the spinal cord totally abolished the hypotensive and tachycardiac responses to i.c.v injection of nitroglycerin (NTG) and reduced the tachycardia induced by i.v. injection of the drug. The hypotensive responses to i.v. injection of sodium nitroprusside were not altered by decerebration. Microinjection of NTG (0.1-1.0 nmol) into anterior hypothalamic medial preoptic area (AH/POA) produced dose-dependent decreases in mean arterial pressure and heart rate, but minimal responses were induced when the same doses of NTG were injected into the rostral ventrolateral medulla. Pretreatment with rauwolscine (2.5 nmol), injected into the AH/POAs, antagonized the depressor responses to NTG when it was administered into the areas or given i.v. However, rauwolscine did not alter the depressor responses induced by i.v. sodium nitroprusside. Prazosin (1.5 nmol) in the AH/POA did not alter the bradycardic effects induced by microinjection of NTG into the areas. (minus)-Epinephrine significantly interacted with alpha-2 adrenoceptor binding sites, but serotonin and NTG did not interact with [3H] clonidine binding sites in cortex membranes. Results suggest that cardiovascular responses after i.v. injection of NTG involve central and peripheral component. AH/POA is one of the central sites involved in the depressor effects of NTG. NTG-induced modulation of noradrenergic transmission appears to stimulate alpha-2 adrenoceptors in the central nervous system, but the drug does not involve direct interaction with alpha-2 adrenoceptors. Hypotensive effects of sodium nitroprusside result from its action at peripheral sites.

Animals↗
PubMed1992

[Pharmacological study on spleen-stomach warming and analgesic actions of Aconitum carmichaeli Debx].

This study presents an observation of the anti-inflammatory effect of Aconitum carmichaeli decoction on water-immersion stress induced gastric ulcer in mice and 0.6 mol/L HCl induced gastric ulcer in rats. The observation showed that the decoction was resistant to the castor oil induced and Cassia angustifolia leaf induced experimental diarrhea in mice, and also had marked analgesic action. It is thus suggested that Aconitum carmichaeli is useful clinically as a spleen-stomach warming and analgesic agent in traditional Chinese medicine.

Analgesics↗
PubMed1992

Molecular cytogenetic study of short arm aberrations in human D, G group chromosomes.

Six cases of Dp+/Gp+, 10 cases of D/G translocation, 1 case of supernumerary marker chromosome, and 1 case of Yqs were studied using molecular and cytogenetic techniques. The Ag-NOR frequencies of the Dp+ and Gp+ groups were found to be higher than those of normal controls, while their satellite association frequencies were lower. Autoradiographic silver grains were not significantly distributed along the p+ part of the marker chromosome as revealed by chromosomal in situ hybridization using an rRNA probe. This result differs from our previous report. It is suggested that there might be different mechanisms for the formation of p+ on acrocentric chromosomes. D/G translocation cases were found to have lost their NOR. A study of supernumerary marker chromosomes and Yqs cases suggested that the marker chromosome and Yqs exerted no phenotypic effect. The mechanism of their formation is discussed.

Adolescent↗