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Biomedical subjects

M Ahmad

Publications and source records attributed to M Ahmad.

At least 109 records · Page 6Linked to original sources
PubMed1999

Differential response of human osteoblast-like cells to commercially pure (cp) titanium grades 1 and 4.

Common dental implants are made of different grades of commercially pure titanium (cpTi) that are more than 99% similar in chemical composition. The objective of this in vitro study was to determine if human osteoblast-like cells, Saos-2, would respond differently when plated on disks of cpTi Grade 1 and Grade 4. Glass disks served as controls. In spite of identical preparation, the two grades of cpTi acquired different surface topographies, as illustrated by scanning electron micrographs and profilometry. Cell responses, such as adhesion, morphology, and collagen synthesis also differed on the two grades of cpTi. Between 4 and 24 h, the rate of cell attachment to Grade 1 differed significantly compared to cell attachment to Grade 4 and to glass. Rhodamine phalloidin fluorescence microscopy showed variations in the actin-based cytoskeleton between grades 1 and 4 cpTi in cell spreading, shape, and the organization of stress fibers. Immunofluorescent staining showed differential expression of vinculin, a focal adhesion protein, on the substrates. At 24 h, the percent of collagen synthesized was significantly more on Grade 1 than on Grade 4 and on glass. Alkaline phosphatase activity was similar on all substrates. The calcium content was significantly higher on Grade 1 than on Grade 4 and on glass at 24 h and at 4 weeks. Thus, commonly used cpTi induced differential morphologic and phenotypic changes in human osteoblast-like cells depending on the grade of the material.

Alkaline Phosphatase↗
PubMed1999

Whiplash Injuries.

The term "whiplash" is not a medical diagnosis, but is the result of soft-tissue trauma to the neck. A whiplash injury occurs as a result of a sudden acceleration or deceleration of the head and neck with respect to the body. This article recommends that patient treatment be individualized.

Journal Article↗
PubMed1999

An in vitro model for mineralization of human osteoblast-like cells on implant materials.

An in vitro mineralizing cell-implant system was developed to study osteoblast attachment, secretion of extracellular (ECM) matrix proteins and mineralization. Saos-2 cells were plated on Tivanium (Tiv, Ti-6A1-4V), Zimaloy (Zim, Co-Cr-Mo) and glass disks. The cells were cultured in alpha-MEM medium with 10% fetal bovine serum and 50 microg ml(-1) ascorbic acid. The cultures were analyzed for calcification and for mRNA expression for ECM proteins after 1, 2, 4 and 6 weeks. Calcium content was significantly higher in cells on Tiv, less on Zim and least on glass disks. With the addition of 3 mm beta-glycerophosphate (beta-GP), the cell layer was more calcified on Zim than on Tiv and all substrates had three times more calcium than cultures without beta-GP. All subsequent experiments were performed without beta-GP. Phalloidin immunofluorescence microscopy of the actin-based cytoskeleton at 2 weeks demonstrated nodules composed of multilayered, cobblestone-appearing osteoblasts overlying calcified matrix which was stained with calcein. On Tiv, calcified nodules were connected in a trabecular-like pattern while on Zim, calcification was dispersed throughout the cell layer. Northern blots for alkaline phosphatase, bone sialoprotein, osteocalcin and alpha1(I) procollagen mRNAs were performed at different time points. The amount and pattern of calcification as well as the expression of ECM-mRNAs differed on each implant material. The results indicate that Tiv stimulates the production of more ECM proteins and mineralized matrix than Zim or glass in this osteoblast-like cell/implant culture.

Alloys↗
PubMed1999

Future of flexible bronchoscopy.

Despite some potential "threats" (Table 3), the future of bronchoscopy is likely full with ever expanding applications in clinical medicine and research (Tables 1 and 2). The role of bronchoscopy in lung cancer continues to expand and the usefulness of newer techniques needs to be established. The role of FB is also ever expanding in the immuno compromised host and critically ill patients. Future studies, however, should concentrate on patient outcome, especially survival and performance status. Therapeutic bronchoscopy has been extended to many areas and the emphasis of future research will likely continue to be at the molecular level rather than on studies of better instruments for retrieval purposes. The most exciting developments are likely to be in the field of gene therapy, which has made remarkable progress in the past decade. Gene therapy can be a powerful technology, but several hurdles must be overcome to make gene therapy a reality for treating human disease in the future. As the cost of technology continues to challenge health care delivery systems, a major challenge for the future of bronchoscopy is to evaluate new technologies and applications based on their impact on patient outcome, survival, and management of cost.

Bronchoscopes↗
PubMed1999

Seeing the world in red and blue: insight into plant vision and photoreceptors.

Plants see light through multiple photoreceptors, including phytochromes and cryptochromes. Cryptochromes are flavoproteins that participate in many blue-light responses, including phototropism in plants and entrainment of circadian rhythms in plants and animals. A novel flavoprotein, NPH1, is also implicated in plant phototropism. Phytochromes function as serine/threonine kinases whose potential interacting partners include cryptochrome (CRY1 and CRY2).

Animals↗
PubMed1999

Cryptochrome 1 controls tomato development in response to blue light.

Cryptochrome genes (CRY) are a novel class of plant genes encoding proteins that bear a strong resemblance to photolyases, a rare class of flavoproteins that absorb light in the blue (B) and UV-A regions of the spectrum and utilise it for photorepair of UV-damaged DNA. In Arabidopsis, both CRY1 and CRY2 are implicated in numerous blue light-dependent responses, including inhibition of hypocotyl elongation, leaf and cotyledon expansion, pigment biosynthesis, stem growth and internode elongation, control of flowering time and phototropism. No information about the in vivo function of CRY genes is available in other plant species. The tomato CRY1 gene (TCRY1) encodes a protein of 679 amino acids, which shows 78% identity and 88% similarity to Arabidopsis CRY1. In order to verify the in vivo function of TCRY1, we constructed antisense tomato plants using the C-terminal portion of the gene. Partial repression of both mRNA and protein levels was observed in one of the transformants. The progeny from this transformant showed an elongated hypocotyl under blue but not under red light. This character co-segregated with the transgene and was dependent on transgene dosage. An additional, partially elongated phenotype was observed in adult plants grown in the greenhouse under dim light and short days with no artificial illumination. This phenotype was suppressed by artificial illumination of both short and long photoperiods. The synthesis of anthocyanins under blue light was reduced in antisense seedlings. In contrast, carotenoid and chlorophyll levels and second positive phototropic curvature were essentially unaltered.

Journal Article↗
PubMed1999

Sphenopalatine ganglion block for treatment of sinus arrest in postherpetic neuralgia.

A 64-year-old woman presented with bradycardia from sinus pauses during exacerbations of postherpetic trigeminal distribution neuralgia. She had underlying systemic lupus erythematosus. Sphenopalatine ganglion blockade was employed to treat her pain. The episodes of bradycardia resolved with successful alleviation of pain. This report emphasizes that a sphenopalatine ganglion blockade can be employed in the treatment and prevention of sinus arrest associated with postherpetic trigeminal distribution neuralgia.

Autonomic Nerve Block↗
PubMed1999

Pulsed dye laser treatment of telangiectasia after radiotherapy for breast carcinoma.

Telangiectasia formed following exposure to X-ray irradiation have been reported to respond well to the pulsed dye laser system. We present the case of a 34-year-old woman with extensive post-radiotherapy skin telangiectasia of the chest wall and axilla who was treated with six sessions of pulsed dye laser treatment, with a considerable improvement in appearance. We recommend the pulsed dye laser as an option in the treatment of post-radiotherapy telangiectasia.

Adult↗
PubMed1999

Hypotensive, hypoglycaemic and toxicological studies on the flavonol C-glycoside shamimin from Bombax ceiba.

Shamimin, a C-flavonol glucoside from Bombax ceiba leaves showed significant potency as a hypotensive agent at the doses of 15 mg/kg, 3 mg/kg, 1 mg/kg and significant hypoglycaemic activity at 500 mg/kg in Sprague-Dawley rats. Further studies revealed that it did not cause any mortality in mice at the dose of 1 g/kg but in rats 500 mg/kg is a lethal dose. Aqueous and methanolic extracts of Bombax ceiba leaves and one of its fractions were also subjected to pharmacological and toxicological screening.

Animals↗
PubMed1999

Cerebrospinal fluid human immunodeficiency virus type 1 (HIV-1) suppression and efavirenz drug concentrations in HIV-1-infected patients receiving combination therapy.

Efavirenz, a potent inhibitor of human immunodeficiency virus type 1 (HIV-1) reverse transcriptase, is a promising addition to the antiretroviral armamentarium. Efavirenz levels and HIV-1 RNA levels were measured in cerebrospinal fluid (CSF) and plasma of 10 HIV-1-infected patients taking efavirenz, 600 mg daily, in combination with other antiretroviral medications. Efavirenz was detected in the CSF at a mean concentration of 35.1 nM (range, 6. 6-58.9 nM), which was above the IC95 for wild-type HIV-1. The mean CSF-to-plasma ratio was 0.61% (range, 0.26%-0.99%). CSF HIV-1 RNA levels were ascertained in 9 of the patients; all were <400 copies/mL after a mean of 26 weeks on therapy. Eight of the 9 patients had no detectable virus in plasma. These results indicate that efavirenz is present in the CSF at low levels and is effective in suppressing CSF viral levels when used in combination therapy.

Acquired Immunodeficiency Syndrome↗
PubMed1999

Clinical characteristics and molecular epidemiology associated with imipenem-resistant Klebsiella pneumoniae.

Eight patients were infected or colonized with imipenem-resistant Klebsiella pneumoniae (IRKP) from December 1994 to November 1995. Initial Klebsiella isolates were susceptible to imipenem but resistant to all cephalosporins, aminoglycosides, and beta-lactam inhibitor combinations. All patients had been in the surgical intensive care unit and had undergone abdominal surgery or tracheostomy during hospitalization. The average age of the patients was 71 years (range, 41-81 years). All patients were treated with imipenem for 5 to 36 days, and IRKP was recovered from each during or after therapy. Pulsed-field gel electrophoresis (PFGE) of the IRKP isolates revealed three distinct clonal patterns. Paired sequential isolates of imipenem-susceptible K. pneumoniae and IRKP from two patients had identical PFGE patterns, suggesting the development of clonal stepwise resistance to imipenem during therapy. Thus, imipenem resistance in Klebsiella may occur when this agent is used for treatment of infection due to ceftazidine- and aminoglycoside-resistant strains.

Adult↗
PubMed1999

Tuberculous peritonitis: fatality associated with delayed diagnosis.

We describe a fatal case of tuberculous peritonitis and review the literature on the diagnostic modalities available to diagnose this entity. We suspect a delayed diagnosis resulted in the death of our patient. Today, the prompt diagnosis of an unknown ascitic process involves laparoscopy. A patient with unknown large volume ascites is the easiest and safest to laparoscope. Using a mini laparoscope, a bedside procedure with instantaneous return can be done. The newer noninvasive tests like determination of ascites fluid adenosine deaminase activity and polymerase chain reaction may be helpful in the prompt diagnosis of peritoneal tuberculosis. We recommend that patients with clinical presentation suggestive of peritoneal tuberculosis have either an aggressive diagnostic workup using high-yield tests or a trial of antituberculous therapy.

Aged↗