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Biomedical subjects

V K Iyer

Publications and source records attributed to V K Iyer.

At least 19 recordsLinked to original sources
PubMed2005

Carcinoma of the tonsil with bilateral breast metastasis: a rare presentation.

With increasing local regional control and survival rates, the incidence of distant metastasis is increasing. Head and neck malignancies traditionally metastasize to the lung, liver and bone. We present a case of an elderly woman who was loco-regionally controlled after radiotherapy for carcinoma of the tonsil, but later presented with breast metastasis. To our knowledge, this metastatic pattern has never been reported in published literature. We also discuss the management of breast metastasis and the need to avoid unnecessary mastectomies in such patients.

Breast Neoplasms↗
PubMed2001

Congenital nephrotic syndrome.

A female infant born at 34 weeks' gestation after several days of ruptured membranes had a Potter-like face and compression-induced limb posture consistent with oligohydramnios. Oedema developed on day 2; initial investigations showed massive proteinuria, hypoalbuminaemia, hyponatraemia, acidosis and marked renal insufficiency. The infant was intubated and despite albumin infusion and intravenous antibiotics she became oligoanuric by day 8 and required haemofiltration. Renal biopsy at this stage showed cystic dilatation of tubules in the cortex and glomerular lesions consisting of shrunken tufts with sclerotic centres and a corona of epithelial cells at the periphery. Due to a very poor prognosis treatment was withdrawn. Postmortem examination of the kidneys confirmed the histological diagnosis of diffuse mesangial sclerosis. Genetic studies found no mutations in WT1 and NPHS1 genes although the entire genes could not be screened for mutations due to lack of DNA.

Fatal Outcome↗
PubMed2000

Prognostic utility of silver stained nucleolar organiser region counting in non Hodgkin's lymphoma.

Silver stained Nucleolar Organiser Region (AgNOR) counting is a well established method of estimating the proliferative activity of a tumour. Their utility in prognostication in Non Hodgkin's Lymphoma (NHL) has not been fully investigated. We analysed hundred cases of NHL, all of which had a minimum of two and a half years of follow up, using histology by International Working Formulation (IWF) and their AgNOR scores. We found the IWF grading to have a good correlation with the outcome. The two and a half year survival for low grade NHL was 90 percent, for intermediate grade NHL was 47 percent and for high grade NHL was 30 percent. AgNOR scores correlated well with IWF grading and classification, with average AgNOR score of 1.82 (SD 0.34) in low grade NHL; 4.47 (SD 2.25) in intermediate grade NHL and 7.07 (SD 4.40) in high grade NHL. Over histology, AgNOR counting yielded additional prognostic information only in the diffuse small cleaved cell NHL (DSC), where finely dispersed NORs were seen. Of the 22 case of DSC included, 11 cases with AgNOR scores less than three had a much better outcome with 75 percent survival at two and a half years. Cases of DSC with AgNOR scores greater than three had a significantly worse outcome with only 25 percent survival at two and a half years (p=0.0103). Such sub-stratification could not be done in any other catergory of NHL using AgNOR scores. Thus, counting of AgNORs in lymphomas with finely dispersed NORs as in DSC is of prognostic value.

Adult↗
PubMed1999

Laryngeal mucosal histology in laryngomalacia: the evidence for gastro-oesophageal reflux laryngitis.

OBJECTIVE: To describe the histopathological changes of the mucosa in laryngomalacia; look for any relationship with gastro-oesophageal reflux and to describe the histological changes of reflux laryngitis in laryngomalacia. METHODS: We examined serial histological sections from nine cases of laryngomalacia, who had aryepiglottoplasty and compared the histopathological features with five cases of postintubation inflammatory laryngitis and five age-matched autopsy specimens of normal larynx. RESULTS: Five of the cases of laryngomalacia had mild inflammation in the form of basal cell hyperplasia and chronic inflammation close to the basement membrane. Deeper subepithelium was oedematous. Two cases had moderate and two cases severe inflammation. The latter showed ulceration and a dense band of chronic inflammation in the immediate subepithelium with underlying oedema. Three of the cases had gastro-oesophageal reflux proven by barium swallow. Two of these showed intraepithelial eosinophils. CONCLUSIONS: A band of inflammation of variable intensity just beneath the epithelium with oedema deep to it is the most important histological feature of laryngomalacia. The presence of intraepithelial eosinophils appears to be a histological indication for reflux aetiology of the inflammation.

Culture Techniques↗
PubMed1999

Wilms' tumor. Role of fine needle aspiration and DNA ploidy by image analysis in prognostication.

OBJECTIVE: To evaluate the utility of cytomorphologic features and DNA ploidy estimation in fine needle aspirates (FNAs), from Wilms' tumors for prognostication. STUDY DESIGN: Twenty-three cases of Wilms' tumor having FNA and follow-up data were selected. Cytomorphology was analyzed by two observers. DNA ploidy was determined in 19 cases by image cytometry by destaining Papanicolaou-stained slides and restaining with Feulgen stain. Various parameters and patient outcomes were compared, and statistical evaluation was done. RESULTS: Poor outcome (12/23 cases) was associated with age < 2 years (P = .01), severe pleomorphism of blastemal cells (4/23 cases, P < .05), very large nucleoli (5/23 cases, P = .075), atypical mitosis (6/23 cases, P = .032) and aneuploidy/tetraploidy of tumor cells (6/29 cases, P = .005). Term unfavorable cytology is proposed when a combination of severe pleomorphism, very large nucleoli and atypical mitosis is seen in FNA smears. Four Wilms' tumor FNAs were characterized as showing unfavorable cytology, and all had a poor outcome (P = .0351). Three of the six cases with aneuploid/tetraploid features also showed unfavorable cytology. CONCLUSION: Unfavorable cytology and aneuploidy/tetraploidy in FNA smears of Wilms' tumor are associated with a poor prognosis.

Age Factors↗
PubMed1998

Fine-needle aspiration diagnosis of foreign body granulomatous reaction presenting as an orbital mass: case report and review of the literature.

Foreign body granuloma is a rare cause for an orbital mass. A case with proptosis and an orbital mass on CT scan is presented. Fine-needle aspiration of the mass was performed. Numerous foreign body giant cells were seen which contained polarizable filamentous material. A diagnosis of foreign body granuloma was rendered which was confirmed on histopathology.

Adult↗
PubMed1991

Reproducibility of the vesicular breath sounds in normal subjects.

Nonfiltered (NF) lung sounds from the apical area of the heart along with lung volumes and ECG signals were recorded from 5 normal subjects. The signals were digitized and subjected to three methods of heart sound cancellation: 75-Hz high-pass filtering (75 HF), ECG-triggered blanking (BL) and adaptive noise cancelling (AF) [IEEE Trans. Biomed. Engng 33: 1141-1148, 1986]. The sound signals were then subjected to the fast Fourier transform algorithm to obtain power spectra. Five breaths from each subject were analyzed, and their spectra were similar and slightly skewed to the right. The average values of mean, median and mode frequencies of the whole breath of 5 subjects, respectively, were for NF: 64.62 +/- 3.74, 44.57 +/- 2.06 and 36.75 +/- 1.79 Hz; for 75 HF: 150.42 +/- 17.49, 114.02 +/- 6.43 and 86.16 +/- 3.13 Hz; for BL: 81.76 +/- 6.02, 52.36 +/- 2.79, 41.10 +/- 3.15 Hz; for AF: 96.87 +/- 11.58, 68.23 +/- 10.44 and 52.25 +/- 8.97 Hz. These values showed no differences between subjects. The F values obtained by the two-way analysis of variance of all breaths of all subjects (mean, median, mode) were: NF: 0.161, 0.341, 0.089; 75 HF: 0.455, 0.042, 0.085; BL: 0.108, 0.082, 0.057; AF: 0.130, 0.204, 0.113 (all p greater than 0.1). The data revealed a remarkable lack of variation within and between subjects, suggesting similar sites and mechanisms of production and transmission.

Adult↗
PubMed1990

Inspiratory and expiratory vesicular breath sounds.

Unfiltered breath sounds (NF) from the apical area of the heart, lung volume and ECG signals were recorded in 5 normal subjects. The signals were digitized and subjected to three methods of heart sound cancellation: 75-Hz high-pass filtering (75 HF), ECG-triggered blanking (BL) and adaptive filtering (AF). The sound signals were then subjected to the fast Fourier transform algorithm to obtain power spectra. Inspiratory and expiratory phase sounds of five breaths of each subject were analyzed separately. The inspiratory and expiratory sound power spectra were very similar and skewed slightly to the right, and therefore characterized by median frequencies. The differences between inspiratory and expiratory median frequencies were insignificant for NF: 42.90 +/- 2.03 (mean +/- SD) vs. 46.64 +/- 2.53 Hz (p greater than 0.1); for 75 HF: 106.43 +/- 10.27 vs. 118.22 +/- 6.30 Hz (p greater than 0.5); for BL: 44.46 +/- 3.33 vs. 66.73 +/- 2.93 Hz (p greater than 0.1), for AF: 49.72 +/- 5.68 vs. 79.20 +/- 13.07 Hz (p greater than 0.1). We conclude that the lack of significant differences suggests similar mechanisms and sites of production of inspiratory and expiratory vesicular breath sounds.

Adult↗
PubMed1990

Adaptive filtering in biological signal processing.

The high dependence of conventional optimal filtering methods on the a priori knowledge of the signal and noise statistics render them ineffective in dealing with signals whose statistics cannot be predetermined accurately. Adaptive filtering methods offer a better alternative, since the a priori knowledge of statistics is less critical, real time processing is possible, and the computations are less expensive for this approach. Adaptive filtering methods compute the filter coefficients "on-line", converging to the optimal values in the least-mean square (LMS) error sense. Adaptive filtering is therefore apt for dealing with the "unknown" statistics situation and has been applied extensively in areas like communication, speech, radar, sonar, seismology, and biological signal processing and analysis for channel equalization, interference and echo canceling, line enhancement, signal detection, system identification, spectral analysis, beamforming, modeling, control, etc. In this review article adaptive filtering in the context of biological signals is reviewed. An intuitive approach to the underlying theory of adaptive filters and its applicability are presented. Applications of the principles in biological signal processing are discussed in a manner that brings out the key ideas involved. Current and potential future directions in adaptive biological signal processing are also discussed.

Animals↗
PubMed1989

Autoregressive modeling of lung sounds: characterization of source and transmission.

In this communication, we discuss the application of autoregressive modeling to lung sounds analysis. The lung sounds source in the airway is modeled as a white noise source, consisting of one or a combination of the following sources: random white noise sequence, periodic train of impulses, and impulsive bursts of energy. The acoustic transmission through the lung parenchyma and chest wall is modeled as an all-pole filter. Using this method, the source and transmission characteristics of lung sounds are estimated separately, based on the lung sounds at the chest wall. To illustrate the potential validity of the model, lung sound segments in known disease conditions were selected from teaching tapes and the source and transmission characteristics were estimated by applying the model. The estimated characteristics were found to be consistent with current knowledge of the generation and transmission of lung sounds in the known conditions.

Analog-Digital Conversion↗
PubMed1989

Characteristics of normal lung sounds after adaptive filtering.

Lung sounds were recorded from five normal male subjects during tidal breathing. Simultaneous electrocardiograms were recorded and used as index signals to generate simulated heart sounds for digital subtraction from recorded lung sounds to obtain purer lung sounds. Five random breaths from each subject were analyzed. Sound signals were band-pass filtered 25 to 1,000 Hz (antialiasing), digitized at 3,000 Hz, and then subjected to (1) direct fast Fourier transform (FFT) without filtering (NF); (2) digital high-pass filtering at 75 Hz and subsequent FFT (75 HzF); (3) adaptive filtering and subsequent FFT (AF). The FFT algorithms of all lung sounds were characterized by mean, median, and mode frequencies. The mean, median, and mode of NF were lower than those of 75 HzF (64.98 +/- 4.04 versus 150.42 +/- 17.49, mean +/- SE, p less than 0.003; 44.57 +/- 2.06 versus 111.81.5.78, p less than 0.0003; 36.81 +/- 1.77 versus 86.16 +/- 3.13, p less than 0.0001) and those of AF (64.98 +/- 4.04 versus 96.87 +/- 11.58, p less than 0.01; 44.57 +/- 2.06 versus 68.23 +/- 10.44, p less than 0.05; 36.81 +/- 1.78 versus 52.24 +/- 8.97, p less than 0.06). The mean, median, and mode of AF were lower than those of 75 HzF (96.87 +/- 11.58 versus 150.42 +/- 17.49, p less than 0.02; 68.23 +/- 10.44 versus 111.81 +/- 5.77, p less than 0.007; 52.24 +/- 8.97 versus 86.16 +/- 3.73, p less than 0.01). The results indicated that by filtering out low frequency heart sounds, the frequency spectrum of lung sounds was moved upward.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗