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Biomedical subjects

A Wang

Publications and source records attributed to A Wang.

341 records · Page 19Linked to original sources
PubMed1979

Crystal structure of 1:1 complex of barbital with 1-methylimidazole.

The prediction of a strong hydrogen-bonding interaction between barbital and 1-methylimidazole was confirmed. Two crystal complexes were obtained, 1:1 and 2:1, and the X-ray structure was determined for the 1:1 complex, which is monoclinic, space group P21/c, with a = 12.236(3) A, b = 11.332(4) A, c = 12.495(4) A, and beta = 120.67(1) degrees. The structure contains disk-shaped hydrogen-bonded tetramers with two molecules of each kind. There is a short NH...N hydrogen bond (2.82 A) in which barbiturate provides the NH donor.

Barbital↗
PubMed1979

Structure of the DNA binding cleft of the gene 5 protein from bacteriophage fd.

The structure of the gene 5 DNA unwinding protein from bacteriophage fd has been solved to 2.3-A resolution by X-ray diffraction techniques. The molecule contains an extensive cleft region that we have identified as the DNA binding site on the basis of the residues that comprise its surface. The interior of the groove has a rather large number of basic amino acid residues that serve to draw the polynucleotide backbone into the cleft. Arrayed along the external edges of the groove are a number of aromatic amino acid side groups that are in position to stack upon the bases of the DNA and fix it in place. The structure and binding mechanism as we visualize it appear to be fully consistent with evidence provided by physical-chemical studies of the protein in solution.

Binding Sites↗
PubMed1979

[Non-amyloid nephrotic syndrome: first isolated manifestation of a kappa light chain myeloma (author's transl)].

The authors describe a case which demonstrates that nephrotic syndromes occuring during the course of a myeloma are not always of the amyloid type. They emphasize the possibility of a dysglobulinemia being involved in a glomerular nephropathy syndrome, especially when there are histological lesions of a glomerulosclerosis. The published literature is reviewed and the possible pathogenesis of these nephropathies briefly discussed: either protein deposits, the nature of which has not been fully determined, or mesangial modifications induced by the filtered light chains.

Diagnosis, Differential↗
PubMedDate not supplied

Balloon aortic valvuloplasty.

Balloon aortic valvuloplasty is a percutaneous, therapeutic option for patients with severe aortic stenosis, yet the effectiveness of this procedure is dependent on the morphology of the stenotic aortic valve and the respective mechanism of dilation. In younger patients with congenital aortic stenosis, acute and intermediate-term results are good. However, in adult patients, in whom degenerative aortic stenosis is the most common cause, the acute clinical and hemodynamic benefits of balloon aortic valvuloplasty are not lasting, as restenosis occurs in most patients within 6 months. Sympatomatic relief for adults undergoing balloon aortic valvuloplasty is only apparent in patients with normal left ventricular function, who generally are also candidates for aortic valve replacement. Furthermore, the long-term survival for adults after balloon aortic valvuloplasty is similar to the natural history of untreated severe aortic stenosis. In this article, the mechanism of balloon aortic valvuloplasty, as well as its clinical and hemodynamic effects, are reviewed in the context of the different morphological types of aortic stenosis. In addition, two large registries of adult patients treated with balloon aortic valvuloplasty provide important information regarding the acute and long-term results of this procedure and are reviewed.

Adult↗
PubMedDate not supplied

Respective roles of immune and nutritional factors in the priming of the immune response in the elderly.

Ninety-six institutionalized elderly (greater than 70 years old) (mean age: 82 +/- 7 years) subjects, negative for tetanus toxoid antibodies were primed with tetanus toxoid vaccination and dinitrochlorobenzene (DNCB). Correlations were studied between some immunological parameters, nutritional parameters prior to immunization and the immune response intensity after it. Levels of tetanus toxoid specific IgG (ELISA assay) were positively correlated with monocyte phagocytosis, DNCB response and prealbumin levels, and negatively correlated with total IgG, monocyte immune degradation and tetanus toxoid lymphocyte stimulation. No correlation was observed with IgA, IgM, PHA stimulation. Tetanus toxoid lymphocyte stimulation correlated positively with response to DNCB, and negatively with tetanus toxoid IgG as well as total IgG. DNCB response correlated with prealbumin, tetanus toxoid IgG and tetanus toxoid lymphocyte stimulation. Therefore, it appears that malnutrition, as measured by prealbumin level, is one of the main factors contributing to the inconstant senile immunodeficiency. Monocyte antigenic degradation function unaltered with age can impair immune response while conserved or increased phagocytosis enhances immune response in the elderly. High total IgG levels were linked with low specific responses to priming antigens. High specific antibody levels also correlated negatively with cellular specific response. It is assumed that regulatory IgG antibody accumulation, likely anti-idiotypic antibodies, play an important role in senile immunological depletion.

Aged↗
PubMedDate not supplied

Comparison of laparoscopic total and partial fundoplication for gastroesophageal reflux.

Approximately 25% of patients with gastroesophageal reflux severe enough to be considered for surgical treatment have dysfunction of esophageal peristalsis in addition to dysfunction of the lower esophageal sphincter. A standard total (i.e., Nissen) fundoplication in these patients may be followed by dysphagia, so many experts recommend a partial fundoplication as an alternative. The goal of this study was to compare the clinical results and changes in esophageal function following laparoscopic total and partial fundoplication. Ninety-three patients with gastroesophageal reflux disease had laparoscopic antireflux operations. Total fundoplication was performed in 50 patients with normal esophageal peristalsis. Partial fundoplication was chosen for 43 patients with severe abnormalities of esophageal peristalsis. The same percentage of patients has resolution of heartburn (93%) and regurgitation (97%) after partial as compared to total fundoplication. Dysphagia developed in four patients (8%) after total fundoplication (one patient required dilatation) and in no patients after partial fundoplication. Both operations produced similar changes in lower esophageal sphincter function, but only partial fundoplication was associated with improvement in esophageal dysfunction. Esophageal acid exposure became normal in 92% of patients after total and in 91% of patients after partial fundoplication. Partial fundoplication improves lower esophageal sphincter pressure and esophageal body function and, in patients with abnormal esophageal peristalsis, it corrects reflux without producing dysphagia. Partial and total fundoplication are both indicated in patients with gastroesophageal reflux disease, and the choice of which procedure to use should be based on each patient"s specific esophageal motor function abnormalities.

Deglutition Disorders↗
PubMedDate not supplied

Importance of preoperative and postoperative pH monitoring in patients with esophageal achalasia.

Gastroesophageal reflux (GER) can develop in patients with esophageal achalasia either before treatment or following pneumatic dilatation or Heller myotomy. In this study we assessed the value of pre- and postoperative pH monitoring in identifying GER in patients with esophageal achalasia. Ambulatory pH monitoring was performed preoperatively in 40 patients with achalasia (18 untreated patients and 22 patients after pneumatic dilatation), 27 (68%) of whom complained of heartburn in addition to dysphagia (group A), and postoperatively in 18 of 51 patients who underwent a thoracoscopic (n=30) or laparoscopic (n=21) Heller myotomy (group B). The DeMeester reflux score was abnormal in 14 patients in group A, 13 of whom had been treated previously by pneumatic dilatation. Two types of pH tracings were seen: (1) GER in eight patients (7 of whom had undergone dilatation) and (2) pseudo-GER in six patients (all 6 of whom had undergone dilatation). Therefore 7 (32%) of 22 patients had abnormal GER after pneumatic dilatation. Postoperatively (group B) seven patients had abnormal GER (6 after thoracoscopic and 1 after laparoscopic myotomy). Six of the seven patients were asymptomatic. These findings show that (1) approximately one third of patients treated by pneumatic dilatation had GER; (2) symptoms were an unreliable index of the presence of abnormal GER, so pH monitoring must be performed in order to make this diagnosis; and (3) the preoperative detection of GER in patients with achalasia is important because it influences the choice of operation.

Adult↗
PubMedDate not supplied

Generation of reactive oxygen species by leukocytes and sperm following exposure to urogenital tract infection.

The association between male urogenital tract infection (UTI) and infertility is still controversial. Oxidative stress caused by reactive oxygen species (ROS) in semen has been suggested to be an important factor in the etiology of poor sperm function through peroxidative damage to the cell membrane. This study explored the potential association between the ROS generation and UTIs by examining ROS production by sperm and seminal leukocytes in response to various infectious and cytokine stimulating factors. Semen and blood samples were obtained from 17 normal donors. Highly motile pure sperm, poorly motile sperm, and polymorphonuclear leukocytes (PMN) were isolated and exposed to various infectious and stimulating factors, including lipopolysaccharide (LPS), gamma interferon (gamma-IFN), tumor necrosis factor-alpha (TNF-alpha), granulocyte, macrophage-colony stimulating factor (GM-CSF), and phorbol myristate acetate (PMA). ROS generation was determined by measuring luminescence in a luminometer. In this study, purified PMNs produced high levels of ROS, and this production was markedly enhanced in the presence of cytokines, LPS, as well as PMA. Pure motile sperm produced low levels of ROS, and ROS production was not enhanced by addition of bacterial products or cytokines. In conclusion, PMNs in semen are the major source of ROS, and ROS production by these cells is enhanced by bacterial products and cytokines. Detection of activation markers and/or soluble factors produced by activated leukocytes in the urogenital tract or semen could enhance the diagnosis and lead to improved therapy of male infertility due to subclinical genital tract infections.

Adult↗
PubMedDate not supplied

Cytopathology induced by mercuric chloride and methylmercury in cultured renal cells of the Atlantic spotted dolphin (Stenella plagiodon).

High mercury concentrations have been reported in various tissues of cetaceans, but the toxicological effects of mercury on cetaceans remain unclear. In vivo study is difficult due to the endangered status of these marine mammals and co-exposure to both mercury and selenium (antagonist of mercury) in the oceanic environment. The present data are the first ultrastructural information on dolphin renal cells exposed to mercury in vitro. Multiple organelle changes were observed in Atlantic spotted dolphin (Stenella plagiodon) renal cells treated with mercuric chloride (HgCl2) or methylmercury chloride (MeHgCl2). Mitochondria and rough endoplasmic reticula were swollen after treatment with HgCl2 or MeHgCl. Mitochondrial dense bodies and small cytoplasmic spherical granules of high electron density were also observed after exposure to MeHgCl. Cytoplasmic vacuoles and myelin-like figures were induced by both HgCl2 and MeHgCl. Nuclear changes included karyolysis, nuclear buds, and a novel observation in mercury-treated cells, vacuolization of (micro-)nucleoli after treatment with HgCl2. These morphological changes (multiple organelle damage and nuclear budding) indicated mercury-treated dolphin renal cells underwent oncosis and necrosis, and supported earlier pathophysiologic findings of diverse toxic actions on genetic, respiratory and other cellular functions.

Animals↗
PubMedDate not supplied

[Ultrasonography of the popliteal fossa. Survey of a small saphenous arteriole before sclerotherapy].

Routine investigation by ultrasonography with pulsed Doppler was carried out in 125 patients, candidates for sclerosing injections of the short saphenous. Study of the contents of the popliteal fossa, of the short saphenous, of the position of its junction in relation to the joint line of the knee, as well as detection of a possible satellite arteriole of the short saphenous was undertaken from a hemodynamic and topographic standpoint. A small calibre satellite arteriole of the short saphenous was a virtually constant finding, situated deep to the junction of the short saphenous, parallel to the latter at its origin, and interposed between the popliteal and short saphenous veins. Variations in the size and/or position of this vessel in relation to the saphenous could be considered as being partially responsible for complications of sclerosing injections in this area. Study involved the junction of the short saphenous, its size, continence and position in relation to the joint line of the knee, as well as the presence, size and position in relation to the saphenous of a satellite arteriole.

Adult↗
PubMedDate not supplied

[16 cases of faulty stripping for primary varices].

In answer to the question of knowing whether it is dangerous or not to carry out the excision of intact saphenous veins, the authors define what they mean by faulty strippings. They study 16 personal cases of such strippings, taking their pre-, per-, and postoperative statements from the case-histories. In the discussion they consider the "whys and wherefores" of this kind of faulty treatment, and the mediocre results obtained in medium and long term.

Adult↗
PubMedDate not supplied

[Should external saphenectomy be routine or eclectic? Results of two series compared].

Based on a comparison between one series where external saphenectomy was routine and another series where external saphenectomy was eclectic, the authors give their preference for excision of the external saphenous when it is clearly diseased, and in this way obtain a 99% success rate. In the discussion, they emphasize that the anatomy of the popliteal fossa can vary, and they attempt to define a plan of management in regard to the external saphenous when it is diseased.

Humans↗