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Biomedical subjects

R Ahluwalia

Publications and source records attributed to R Ahluwalia.

8 recordsLinked to original sources
PubMed2001

Power-law statistics for avalanches in a martensitic transformation.

We devise a two-dimensional model that mimics the recently observed power-law distributions for the amplitudes and durations of the acoustic emission signals observed during martensitic transformation [Vives et al., Phys. Rev. Lett. 72, 1694 (1994)]. We include a threshold mechanism, long-range interaction between the transformed domains, inertial effects, and dissipation arising due to the motion of the interface. The model exhibits thermal hysteresis and, more importantly, it shows that the energy is released in the form of avalanches with power-law distributions for their amplitudes and durations. Computer simulations also reveal morphological features similar to those observed in real systems.

Journal Article↗
PubMed1995

A bifunctional monocyclic beta-lactam cross-links across the active site of beta-lactamase.

A 4-alkoxy-2-azetidinone behaves as a bifunctional active site-directed inhibitor of the class A beta-lactamase from Bacillus cereus 569/H. It cross-links SER 70 and LYS 234 as it binds in a approximately 1:1 ratio. The cross-linked enzyme is irreversibly inhibited while the secondary structure is partially stabilized under conditions when the native enzyme is otherwise converted to a form with no detectable secondary structure by circular dichroism.

Acetamides↗
PubMed1994

Scintigraphic appearance of bone during external beam irradiation.

Separate imaging studies employing Tc-99m MDP, In-111 labeled leukocytes, and Tc-99m SC were performed in a patient receiving external beam radiation therapy to the mediastinum and left hemithorax. The leukocyte scan demonstrated greatly increased activity at the site of the radiation port. The bone marrow (sulfur colloid) scan was normal and the bone scan demonstrated only minimally increased activity in the irradiated region. The varying appearance of these scans may represent the difference in the early effect of radiation on bone and bone marrow elements.

Bone Marrow↗
PubMed1994

Bilateral fatigue fractures of the radial shaft in a gymnast.

A 24-year-old female gymnast had a 3-month history of bilateral forearm pain. A Tc-99m MDP bone scan demonstrated focally increased activity in the radial shafts on blood pool and delayed images, characteristic of fatigue fractures. Fatigue fractures commonly occur in the lower extremities. Upper extremity fatigue fractures, in contrast, are uncommon and usually involve the humerus or ulna. Fatigue fracture of the radial shaft from gymnastic exercise has not been previously reported.

Adult↗
PubMed1994

The efficacy of indium-111-polyclonal IgG for the detection of infection and inflammation.

UNLABELLED: The purpose of this study was to determine the efficacy of 111In-polyclonal immunoglobulin (IgG) for the diagnosis of infection or inflammation. METHODS: Fifty-three patients with suspected infection were prospectively studied. Each underwent an 111In-polyclonal IgG study; biopsy, surgery, additional nuclear medicine scans and radiographic studies were used to confirm the IgG scan results. RESULTS: The polyclonal IgG scan had a sensitivity of 97.9% and a specificity of 94% for infection or inflammation. When only infection or severe inflammation such as bowel infarction was considered, the sensitivity remained the same but the specificity fell to 83%. Chronic infections were detected equally as well as acute infections. Antibiotics, steroids, anti-inflammatory agents, diabetes and diminished renal function did not affect scan sensitivity. There were no adverse reactions to the radiopharmaceutical. Three patients underwent extended imaging. Their scans stayed positive for an average of 8 days. Three patients treated for infection had their scans turn negative on repeat study, confirming the efficacy of their antibiotic therapy. CONCLUSION: Indium-111-polyclonal IgG is an effective imaging agent of infection and/or inflammation that is useful in a variety of infections and in severe inflammatory diseases. The ease of preparation and safety make it an attractive alternative to labeled leukocytes.

Adult↗
PubMed1993

The use of computer-assisted diagnosis in cardiac perfusion nuclear medicine studies: a review (Part 3)

Computer-assisted diagnosis (CAID) is commonly used to evaluate cardiac nuclear medicine studies such as thallium perfusion scans. Part 1 of this series (Journal of Digital Imaging, 5:209-222, 1992) reviewed the basic theory underlying CAID in nuclear medicine and its use in planar thallium imaging. Part 2 discussed the application of CAID to SPECT perfusion studies (Journal of Digital Imaging, 6:1-15, 1993). This article reviews new variations of CAID programs for SPECT imaging and the application of expert systems and neural networks to CAID of nuclear medicine perfusion studies.

Algorithms↗
PubMed1984

Antigen requirements and specificity of a microplate enzyme-lined immunosorbent assay (ELISA) for Marek's disease viral antibodies in chicken, mouse and rabbit sera.

A rapid indirect enzyme linked immunosorbent assay for the detection of antibodies against Marek's disease virus in mouse, chicken and rabbit-sera has been established. Optimal sensitivity was obtained by using 10 micrograms/ml of partially purified viral proteins. Various experimental procedures performed to eliminate nonspecific reactions are described. Best results were obtained by the introduction of NP 40 at a concentration of 0.1% in sera. With mouse sera, the pretreatment of plaques with poly-L-lysine before antigen fixation substantially reduced the occurrence of nonspecific reactions.

Animals↗