Biomedical subjects
D Singh
Publications and source records attributed to D Singh.
Congenital malformations--a retrospective study of 10,000 cases.
The frequency of congenital malformations in a retrospective study done on 10,000 consecutive births from January 1983 to March 1989 was 3.6%. The predominant system involved was CNS. Major malformations constituted 79.7% of the total. Malformations were seen 4 times more often among still births. The common malformations in still births were also of CNS. The frequency of malformations was similar in both the sexes, though genitourinary anomalies were commoner among male, while anencephaly in female babies. A statistically significant increase in the frequency of congenital malformations was observed with decreasing gestation and birth weight. There was a significant correlation between maternal factors, like previous abortions, drug intake and fever during 1st trimester, diabetes mellitus, pre-eclamptic toxemia, antepartum hemorrhage and congenital malformations in the baby.
Perinatal mortality in Ludhiana, Punjab--a seven year hospital study.
Perinatal deaths occurring over a seven year period were studied in a teaching hospital in Punjab. Causes of death were analysed as per Wigglesworth's classification. We have further modified this by correlating different gestations and weight groups with causes of death. The perinatal mortality rate (PNMR) in the present study was 74/1000 and showed a downward trend secondary to a statistically significant fall of early neonatal mortality. There was a decline in PNMR among babies of 1500-2000 g. birth weight and 33-36 weeks gestation. Asphyxia and macerated still births were found to be the two main causes of death. Macerated still births were seen more commonly among babies of lower weight at all gestations. The PNMR of babies born to booked mothers was 22/1000 as compared to 152/1000 among unbooked mothers. It was concluded that to bring down the PNMR, economic development alone is not enough. Provision of adequate antenatal care to all mothers, health education and timely referral of high risk mothers is very essential.
Metastatic tumour in the parotid gland.
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Localized bullous separation of Descemet's membrane after previous cataract surgery.
This paper describes four cases of localized bullous separation of Descemet's membrane that occurred from more than 1 year to 7 years after cataract surgery. In all eyes, fluid resembling a hypopyon (pseudohypopyon) filled the space created by the separation. In three cases, the fluid was white. In one of these, pathological examination of the fluid showed mostly necrotic but a few viable squamous epithelial cells. In the fourth case in which the fluid was whitish red, there were many capillaries along the edge of the separation and there was evidence of injury to the nearby epithelium. The one case with poor visual acuity improved after the fluid was removed.
Arthroscopic subacromial decompression: results and factors affecting outcome.
Arthroscopic subacromial decompression was performed on 114 patients with rotator cuff impingement who had not responded to nonoperative measures. None of the patients had a full-thickness cuff tear. Patients with associated instability, symptomatic acromioclavicular joint disease, or ruptures of the long head of biceps were not included. Results were determined by questioning patients about their satisfaction with the outcome of surgery and by functional assessment of the shoulder with the parameters of pain, ability to perform daily activities, and range of motion according to the Constant scoring system. When reviewed at a mean interval of 19 months after surgery, 85 patients (75%) were satisfied with the outcome. Pain scores improved by an average of 8.6 points; "activities of daily living" scores improved by an average of 5.8 points; range-of-motion scores improved by an average of 3.6 points. The improvements in all 3 parameters scored were significant (P < .05). The following variables were statistically analyzed to assess their influence on final outcome: age, sex, occupation, duration of symptoms before surgery, dominance of the affected shoulder, outcome of the impingement test, state of the cuff, and experience of the surgeon performing the operation. The duration of symptoms before surgery was the most significant predictor of outcome. Symptoms of prolonged duration were associated with an unsatisfactory subjective results (P < .01) and with smaller improvements in the parameters of the Constant score (P < .001). Recovery after arthroscopic subacromial decompression and eventual outcome were related to the extent of cuff damage. Patients with partial thickness tears or fraying of the cuff had a delayed return to work (P < .001) and were found to have smaller increases in the pain and range-of-motion scores (P < .05). A satisfactory subjective result was most often associated with a positive impingement test (P < .05). Unsatisfactory outcomes were associated with a questionable diagnosis and lack of clear evidence of impingement at arthroscopy, inadequate decompression of the subacromial space, or the presence of calcium deposits in the rotator cuff.
Peptide-based intracellular shuttle able to facilitate gene transfer in mammalian cells.
Loligomers are peptide-based intracellular vehicles able to penetrate cells and self-localize into distinct cellular compartments. Loligomers can be rapidly assembled by automated solid-phase approaches and were designed to act as nonviral, nonlipophilic intracellular shuttles. One nucleus-directed loligomer, termed loligomer 4, was evaluated for its ability to function as a transfection agent. Loligomer 4 readily associates with plasmids to form noncovalent complexes. The migration of loligomer 4-plasmid complexes into cells was monitored by flow cytometry and fluorescence microscopy. Populations of plasmids labeled with 7-AAD exist either free or in association with loligomer 4 inside cells and are visible throughout the cytosol and nucleus of chinese hamster ovary (CHO) cells. Loligomer 4-plasmid complexes were not cytotoxic to cells and were readily imported by most cells (>70%). CHO cells were transfected with complexes of loligomer 4 and plasmids harboring luciferase, green fluorescent protein or beta-galactosidase reporter genes. The transfection efficiency of loligomer 4-plasmid DNA complexes was greater when cells were maintained as suspensions instead of monolayers. Transfections could be performed with cells suspended in serum-containing medium. The observed levels of transfection, however, were modest with 5-10% of CHO cells expressing either a green fluorescent protein or the enzyme beta-galactosidase. Loligomers have recently been observed in vesicular compartments [Singh, D., Kiarash, R., Kawamura, K, LaCasse, E. C., and Gariépy, J. (1998) Biochemistry 37, 5798-5809] and differences between levels of cellular import and transfection efficiency may well reflect the need to optimize the release of loligomers and their complexes from these compartments in future designs. In summary, loligomer 4 behaves as a stable, soluble and effective transfection agent. These results demonstrate the feasibility of designing loligomers able to act as intracellular guided agents aimed at gene transfer applications.
Potentiation of chlorin e6 photodynamic activity in vitro with peptide-based intracellular vehicles.
Photodynamic therapy (PDT) is a targeted treatment modality where photosensitizers accumulate into cells and are selectively activated by light leading to the production of toxic species and cell death. Focusing the action of photosensitizers to a unique intracellular target may enhance their cytotoxicity. In this study, we demonstrate that the routing of the porphyrin-based photosensitizer chlorin e(6), to the nucleus of cells can significantly alter its toxicity profile. The cellular localization of chlorin e(6) was achieved by coupling the chromophore during solid-phase synthesis to a nucleus-directed linear peptide (Ce6-peptide) or a branched peptide (Ce6-loligomer) composed of eight identical arms displaying the sequence of the Ce6-peptide. These constructs incorporated signals guiding their cytoplasmic uptake and nuclear localization. Ce6-peptide and Ce6-loligomer displayed an enhanced photodynamic activity compared to unconjugated chlorin e(6), lowering the observed CD(50) values for CHO and RIF-1 cells by 1 or more orders of magnitude. The intracellular accumulation of Ce6-peptide and Ce6-loligomer was assessed by electron and confocal microscopy as well as by flow cytometry. Constructs were internalized by cells within an hour and by 6 h, the release of active oxygen species could be observed within the nucleus of cells pretreated with Ce6-loligomer. These results highlight the utility of designing peptides as vehicles for regulating the intracellular distribution of photosensitizers such as chlorin e(6) in order to maximize their efficacy in PDT.
Second to fourth digit ratio: ethnic differences and family size in English, Indian and South African populations.
BACKGROUND: The second to fourth digit ratio (2D:4D) is lower in men than in women. 2D:4D may be established in utero and is negatively correlated with sperm counts and testosterone in men and positively correlated with oestrogen in men and women. Negative associations between male 2D:4D and family size and positive associations between female 2D:4D and family size have been found in some European populations. AIM: The study seeks to investigate the relationship between 2D:4D and family size in samples from Europe, Asia and Africa. SUBJECTS AND METHODS: Measurements of right hand 2D:4D were made in English (Merseyside, n = 403), Indian (Sugali and Yanadi, n= 160) and South African (Zulu,n = 258) populations. RESULTS: 2D:4D was weakly sexually dimorphic and showed strong ethnic differences. There were significant associations between 2D:4D and family size. For males these included negative associations in English and South African samples, and in the total sample. In females there was a positive association in the English sample, a negative association in the South African sample, and the total female sample showed a positive relationship between 2D:4D and family size. CONCLUSIONS: 2D:4D showed weak sex and strong ethnic differences. Low values of 2D:4D were associated with large family size in men. The situation was less clear in women but on balance there was evidence to support a relationship between high values of 2D:4D and large family size.
Sampling frequency of the RR interval time series for spectral analysis of heart rate variability.
Spectral analysis of heart rate variability (HRV) is an accepted method for assessment of cardiac autonomic function and its relationship to numerous disorders and diseases. Various non-parametric methods for HRV estimation have been developed and extensive literature on their respective properties is available. The RR interval time series can be seen as a series of non-uniformly spaced samples. To analyse the power spectra of this series using the discrete Fourier transform (DFT), we need to interpolate the series for obtaining uniformly spaced intervals. The selection of sampling period plays a critical role in obtaining the power spectra in terms of computational efficiency and accuracy. In this paper, we shall analyse the RR interval time series from selected subjects for different sampling frequencies to compare the error introduced in selected frequency-domain measures of HRV at a constant frequency resolution for a specific duration of electrocardiogram (ECG) data. It should be pointed out that, although many other error causes are possible in the frequency-domain measures, our attention will be confined only to the performance comparison due to the different sampling frequencies. While the choice of RR interval sampling frequency (f(s)) is arbitrary, the sampling rate of RR interval series must be selected with due consideration to mean and minimum RR interval; f(s = )4 Hz was proposed for a majority of cases. This is an appropriate sampling rate for the study of autonomic regulation, since it enables us to compute reliable spectral estimates between dc and 1 Hz, which represents the frequency band within which the autonomic nervous system has significant response. Furthermore, resampled RR intervals are evenly spaced in time and are synchronized with the samples of the other physiologic signals, enabling cross-spectral estimates with these signals.
An improved windowing technique for heart rate variability power spectrum estimation.
Spectral analysis of heart rate variability (HRV) is an accepted method for assessment of cardiac autonomic function and its relationship to numerous disorders and diseases. Discrete Fourier transform (DFT) based methods are widely used for their easy applicability, computational speed and the possibility for direct interpretation of results. This study assesses the limitation of windowing of the RR interval series of power spectrum estimation using DFT for heart rate variability studies. The mean value of the RR interval series should be subtracted before windowing. This may leave a small residual DC component after windowing, but the RR interval series is properly tapered to zero at the beginning and end of the window. However, if the windowed RR interval series has a non-zero mean then subtracting this mean will create an abrupt transition between the first and last data points, and the padded zeros. This is equivalent to superimposing upon the RR interval series a rectangular pulse of the same length as the window, with a height equal to the subtracted mean value. In the present paper an approach to overcome the above effects of the window in reducing the signal energy and introducing the low frequency component into spectrum has been suggested and incorporated. Result have been compared for DC biasing of windowed data spectrum, bias of windowed data removed by substraction of mean data, and data processed to remove windowed mean level and to maintain mean power. Thus the preprocessing of RR interval series with this method improves the accuracy of HRV analysis methods. The study was carried out by smoothing the complete RR interval series by single Hann window and by 50% overlapping the data segments of 256 data points followed by the DFT. Overlapping the data segments provides equal weight to all values in the RR interval series and smoothed spectral estimate with clearly dominant peaks in low- and high-frequency regions.
Spectral evaluation of aging effects on blood pressure and heart rate variations in healthy subjects.
The background to heart rate variability (HRV) and blood pressure variability (BPV), and their determinants and physiological correlates, remain obscure. The impact of age must be taken into account if HRV and BPV are used for predictive purposes in clinical settings. Healthy subjects show wide inter-individual variation in their heart rate behaviour and the factors affecting heart rate dynamics are not well known. This paper has undertaken to evaluate heart rate variability (HRV) and baroreflex sensitivity (BRS) in a random sample of subjects without evidence of heart disease, and to estimate the relation of HRV and BPV behaviour to age. The aim of this study was to analyse the effects of ageing on HRV and BPV for simultaneous recordings of electrocardiograph (ECG) and blood pressure (BP) signals at rest in healthy subjects. We studied eight young (21-34 years old) and eight elderly (68-85 years old) rigorously screened subjects from the Fantasia Database to make the reproducibility and comparability of the results more extensive. Time- and frequency-domain analysis of HRV and BPV was performed on 5-minute ectopic-free recordings. BRS on the heart was estimated by frequency-domain analysis of spontaneous variability of systolic blood pressure (SBP) and RR interval. It has been observed that compared to young the elderly subjects have (i) diminished HRV; (ii) a shift in the power spectral density and median frequency to low frequency side for HRV and to higher frequency side for BPV; and (iii) increased low-frequency alpha index and decreased high-frequency alpha index of BRS with overall alpha index augmented. The results convey that normal ageing in the absence of disease is associated with lesser parasympathetic regulation of heart rate. Thus it is concluded that the age is an important factor to be considered for prognosis and diagnosis by HRV and BPV. For reliable clinical applications, more research needs to be done on a broad spectrum of subjects. In addition, these observations will prove to be useful for dynamic modelling of cardiovascular regulation for testing the authentication of new techniques for analysis purposes.
True heartburn: a case of gastropericardial fistula.
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Performance of obese humans on transfer of training and reaction time tests.
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Vascular access: a lifeline. Thoughts on the situation in India.
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Rhabdomyolysis.
Rhabdomyolysis is a condition caused by skeletal muscle injury and release of muscle cell contents into the circulation. It may result in myoglobinuria, the filtration of myoglobin into the urine, and is often associated with acute renal failure (ARF). Rhabdomyolysis may complicate many disease states. In some, such as crush injury, muscle injury is obvious; in others, such as drug overdose, it may never be apparent. It may occur in the setting of an altered mental status, and even in the conscious patient, it may occur with minimal symptoms or physical findings. Therefore, diagnosis requires a high level of suspicion and appropriate sensitivity to abnormal laboratory values. Many insults can precipitate rhabdomyolysis and myoglobinuria. Disruption of the muscle cell membrane may result from a direct mechanical or toxic insult to the membrane or an inability to maintain ionic gradients across the membrane (as in ischemia or extreme exertion). This article reviews the etiology, pathogenesis, clinical features, complications, and management of rhabdomyolysis, particularly crush injuries in the setting of a major disaster.
Synchronous adenocarcinoma and MALT lymphoma of stomach.
We describe a patient in whom adenocarcinoma and lymphoma occurred simultaneously in the stomach. She presented with pain and lump in the epigastrium with history of hematemesis. Endoscopy revealed a growth involving the lesser curvature, and biopsy showed poorly differentiated carcinoma. Histological examination of the gastrectomy specimen showed synchronous diffuse adenocarcinoma with primary lymphoma of MALT type. The latter entity is known to be associated with Helicobacter pylori infection.