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Biomedical subjects

T K Bhattacharyya

Publications and source records attributed to T K Bhattacharyya.

At least 19 recordsLinked to original sources
PubMed2004

Synonymous codon usage in Lactococcus lactis: mutational bias versus translational selection.

In this study codon usage bias of all experimentally known genes of Lactococcus lactis has been analyzed. Since Lactococcus lactis is an AT rich organism, it is expected to occur A and/or T at the third position of codons and detailed analysis of overall codon usage data indicates that A and/or T ending codons are predominant in this organism. However, multivariate statistical analyses based both on codon count and on relative synonymous codon usage (RSCU) detect a large number of genes, which are supposed to be highly expressed are clustered at one end of the first major axis, while majority of the putatively lowly expressed genes are clustered at the other end of the first major axis. It was observed that in the highly expressed genes C and T ending codons are significantly higher than the lowly expressed genes and also it was observed that C ending codons are predominant in the duets of highly expressed genes, whereas the T endings codons are abundant in the quartets. Abundance of C and T ending codons in the highly expressed genes suggest that, besides, compositional biases, translational selection are also operating in shaping the codon usage variation among the genes in this organism as observed in other compositionally skewed organisms. The second major axis generated by correspondence analysis on simple codon counts differentiates the genes into two distinct groups according to their hydrophobicity values, but the same analysis computed with relative synonymous codon usage values could not discriminate the genes according to the hydropathy values. This suggests that amino acid composition exerts constraints on codon usage in this organism. On the other hand the second major axis produced by correspondence analysis on RSCU values differentiates the genes into two groups according to the synonymous codon usage for cysteine residues (rarest amino acids in this organism), which is nothing but a artifactual effect induced by the RSCU values. Other factors such as length of the genes and the positions of the genes in the leading and lagging strand of replication have practically no influence in the codon usage variation among the genes in this organism.

Codon↗
PubMed2001

A histologic analysis of three-dimensional versus two-dimensional tissue expansion in the porcine model.

OBJECTIVE: Recently, a two-dimensional Silastic Dacron stretching skin device has been developed for scalp reduction surgery. Attached subgaleally, this device stretches skin over time, while avoiding the visible volumetric distention that is typical of three-dimensional tissue expanders. Unlike three-dimensional expanders, the histological changes observed with a two-dimensional stretching device have not been described in the literature. The present study compares the histological effects of two-dimensional and three-dimensional skin tissue expansion in the porcine model. STUDY DESIGN: A university Institutional Review Board-approved study in which 16 domestic piglets were used. The 16 piglets were divided evenly into four cohorts as follows: 1, 1-week control cohort; 2, 1-week experimental cohort; 3, 4-week control cohort; and 4, 4-week experimental cohort. METHODS: Tissue expanders (three-dimensional) and Dacron Silastic tissue stretchers (two-dimensional) were surgically inserted into the lateral skin of 16 domestic pigs. Animals were killed at either 1 or 4 weeks based on group assignment. Light microscopic ocular micrometry and stereological point counting were used to determine the depth of the epidermis, dermis, and subdermal adipose tissue layer; width of the panniculus muscle; diameter of sweat gland follicles; percentage ratio of dermal collagen, blood vessels, and tissue space; and epidermal mitotic index in 100 specimens. One-way ANOVA was used to evaluate statistical differences. RESULTS: Both tissue expanders yielded increased values compared with control subjects, with respect to epidermal, dermal, and fat widths and blood vessel counts, whereas adnexal structures in the panniculus muscle width were unaltered. CONCLUSIONS: Although statistically the two types of expansion produced histologically similar changes, the degree of change varied according to the type of expander that was used and the duration of tissue expansion. Most notably, three-dimensional expansion produced more tissue gain per unit area expanded at both the 1-week and the 4-week time intervals, and early (1-week) two-dimensional tissue expansion stimulated a greater angiogenic response than three-dimensional expansion. These findings will assist the surgeon in understanding the physical changes that occur with these two forms of tissue expansion, as well as the potential clinical advantages and shortcomings of each method.

Adipose Tissue↗
PubMed2000

An evaluation of fibrin tissue adhesive concentration and application thickness on skin graft survival.

OBJECTIVES: To examine the effects of fibrinogen concentration and application thickness of fibrin tissue adhesive on skin graft survival. STUDY DESIGN: Prospective controlled study. METHODS: Ten domestic pigs were included in the study. A 20 x 5-cm area of skin was harvested bilaterally along the flanks of the animals using a Padgett dermatome. The harvested grafts were trimmed into four 4 x 4-cm squares. Donor sites were treated according to group assignment and the non-meshed grafts were placed on the side opposite their initial orientation and secured with staples. Both single- and multiple-donor human fibrin tissue adhesive preparations, with low and high average fibrinogen concentrations of 30 mg/mL and 60 mg/ mL, were used. Adhesive preparations were applied in either a thin layer (0.015 mL/cm2) or a thick layer (0.06 mL/cm2) using a spray applicator. A constant thrombin concentration of 10 U/mL was used in the study. No adhesive was used in the control group and grafts were stabilized with staples. No topical dressings were applied to any of the treatment sites. Animals were sacrificed 4 weeks after graft application. RESULTS: Based on statistical analysis, thickness of adhesive application had a significant effect on skin graft survival. Percent mean graft survival in the control and thin application groups was found to be 92% and 97.8% respectively; the mean survival rate in the thick application group was 63.1%. Fibrinogen concentration, when evaluated independently within the thin and thick application groups, was found to have no significant effect on graft survival. CONCLUSION: Independent of fibrinogen concentration, a thin layer of fibrin tissue adhesive, when applied between two opposing surfaces, does not interfere with and may support the healing process, whereas a thick layer of adhesive inhibits skin graft healing.

Animals↗
PubMed2000

Evaluation of LR white resin for histology of the undecalcified rat tibia.

Histology of plastic embedded undecalcified bone represents a challenging problem to the histotechnologist. We outline here an exploration of LR White resin as a suitable medium for histologic study of undecalcified rat tibia. A procedure was developed for light microscopy of rat tibia embedded in LR White and sectioned by sawing-grinding technics. The specimens were fixed in 10% neutral buffered formalin or alcohol-acetic acid-formol, dehydrated in ethanol, defatted in chloroform followed by resin infiltration and heat-curing of embedded blocks. The procedure of dehydration, defatting, infiltration, and polymerization can be completed within 10 days. Cold curing with accelerator provided by the manufacturer did not yield superior results compared to blocks cured with heat. Thick sections were obtained using a diamond wire saw, attached to plexiform slides, then ground and polished. Surface staining with Von Kossa silver reagent or toluidine blue revealed satisfactory morphological preservation of the mineralized bone sections. Artifacts like small bubbles appeared occasionally and could not be avoided despite prolonged infiltration or cold curing of blocks. Our method is relatively simple for base-line histologic study of rat tibia. The method offers advantages such as easy adaptability, reliable stainability, contrast, and resolution of bone architecture and marrow cells. Two other embedding media, Micro-Bed resin and Unicryl, were also tested, but produced inferior results.

Acrylic Resins↗
PubMed1998

Auditory brain stem response in young and old guinea pigs.

OBJECTIVE: To characterize age-related auditory changes in genetically similar guinea pigs. BACKGROUND: In humans and animals, changes in hearing are known to occur with age. METHODS: Brain stem-evoked responses were measured in genetically similar guinea pigs that ranged 6-36 months in age. Changes in hearing and the input/output function curve were determined. RESULTS: Threshold shift with increase in age was seen. Marked reduction in amplitude of response with increasing age was also demonstrated. No change was seen in latency or interpeak interval. CONCLUSIONS: In genetically similar guinea pigs, age-related changes in threshold occurred. Latency and interpeak intervals remained unchanged. Amplitude of response decreased substantially after 12 months of age to a greater extent than predicted by threshold shifts alone. This phenomenon appears important in understanding the pathophysiology of age-related hearing loss.

Age Factors↗
PubMed1998

Effect of calcium-channel blocking drugs on focal ventricular arrhythmias induced by sub-epicardial epinephrine infusion in cats.

Sub-epicardial infusion of epinephrine (EP) in the dose of 3 x 10(-3) M in 2.5 x 10(-3) M CaCl2-0.9% NaCl (calcium-saline vehicle) at the rate of 10 microliters in the right ventricular myocardium of mongrel cats weighing between 2.8 and 3.3 kg, produced uniform, reversible and reproducible focal ventricular arrhythmia (VA) of varrying intensity and duration. Infusion of two calcium-channel blocking agents, verapamil (VP) and nifedipine (ND) at the site of arrhythmogenesis, in equimolar concentration of 3 x 10(-3) M alongwith EP in the same vehicle reduced the incidence, duration, peak and mean frequencies of arrhythmias while, the latent period of onset of arrhythmias increased significantly. Verapamil in equimolar concentration of 3 x 10(-3) M was found to be more effective than nifedipine in antagonizing EP-induced ventricular arrhythmias.

Animals↗
PubMed1996

Vascular anatomy of the nose and the external rhinoplasty approach.

OBJECTIVE: To characterize the venous, lymphatic, and arterial blood supply of the nose and determine the effect of the external rhinoplasty approach on this vasculature. We hypothesized that dissection in the areolar tissue plane below the musculoaponeurotic layer of the nose will preserve the nasal vasculature and minimize postoperative nasal tip edema. DESIGN: The study included preoperative and postoperative clinical evaluation, cadaver dissection, and histologic examination. In the clinical section, lymphoscintigraphy was performed before and after rhinoplasty using the endonasal (transnostril) or external (open) approach. Additionally, nasal tip edema was subjectively quantified at specified interval after surgery. In the cadaver dissection section, 15 fresh cadavers were dissected to identify the venous and arterial vasculature. In the histology section, fresh nasal tissue was examined by light microscopy to verify the anatomy of arteries, veins, and lymphatic vessels. SETTING: Subjects for the clinical section of the study were volunteers undergoing primary rhinoplasty surgery at the University of Illinois College of Medicine at Chicago. PATIENTS: Lymphoscintigraphy was performed on nine patients who underwent rhinoplasty surgery. Seven of these patients underwent postoperative lymphoscintigraphy. INTERVENTIONS: The rhinoplasty procedures included three different methods of exposure of the nasal structures. Two patients underwent an endonasal (transnostril) nondelivery approach using a transcartilaginous incision. Five patients underwent the external approach with three receiving dissection in the areolar tissue plane below the musculoaponeurotic layer (preserving major nasal vasculature) and two undergoing dissection above the musculoaponeurotic layer (disrupting nasal vasculature). MAIN OUTCOME MEASURES: In the clinical section of the study, the outcome measures were tracer flow as seen on lymphoscintigraphy and tip edema scores subjectively quantitated on a scale from 1 (none) to 4 (maximal). RESULTS: Clinical Section: Lymphoscintigraphy revealed flow of tracer along the lateral aspect of the nose (cephalic to lateral crura) to the preparotid lymph nodes. Postoperative scans revealed preservation of flow of tracer with the endonasal (transnostril) approach and the external approach with submusculoaponeurotic areolar tissue plane dissection. There was loss of normal flow of tracer with the external approach using dissection that disrupted the musculoaponeurotic layer with supratip debulking. The nasal tip edema scores for the transnostril and external approach using areolar plane dissection were significantly lower than the external approach with disruption of the musculoaponeurotic layer. Cadaver Dissection Section: Other than the lateral nasal veins, the major arteries, veins, and lymphatic vessels ran superficial to the musculoaponeurotic layer of the nose. The lateral and dorsal nasal and the columellar arteries comprise an alar arcade that provides the major blood supply to the flap elevated in the external rhinoplasty approach. Histologic Section: Light microscopy of plastic resin sections verified the lymphoscintigraphic and cadaver dissection findings. The lymphatic vessels were located primarily in the reticular dermis above the muscle layer. CONCLUSIONS: The major arterial, venous, and lymphatic vasculature courses in or above the musculoaponeurotic layer of the nose. In the external rhinoplasty approach, dissection in the areolar tissue plane below the musculoaponeurotic layer will minimize tip edema and protect against skin necrosis by preserving the major vascular supply to the nasal tip.

Cadaver↗
PubMed1996

Fibroblast growth factor-induced motor end plate regeneration in atrophic muscle.

OBJECTIVE: To determine whether fibroblast growth factor 1 implanted with viable nerve into atrophic muscle will stimulate formation of functional, acetylcholine producing motor end plates. DESIGN: Twelve male Lewis rats underwent predenervation of the hamstring muscle 8 weeks before implantation of the nerve at a site distant from the original motor end plate. Six animals underwent implantation of the tagged nerve ending into atrophic muscle with 50 microgram of fibroblast growth factor 1 in a fibrin adhesive carrier (group 1). Three animals underwent implantation with nerve, fibrin adhesive, and no fibroblast growth factor 1 (group 2); and three animals underwent implantation with fibroblast growth factor 1 and fibrin adhesive with no nerve (group 3). Animals were killed 9 weeks after implantation and nerve and muscle specimens were harvested. MAIN OUTCOME MEASURES: Histoenzymologic methods for acetylcholinesterase and silver impregnation of nerve fibers were performed 9 weeks after fibroblast growth factor 1-fibrin adhesive implantation. Variables included the number of motor end plates per highpower field and motor end plate length. RESULTS: Robust axonal sprouting and formation of multiple motor end plates were found arborized in serial fashion equidistant around the implanted nerve ending. Rare extrasynaptic staining occurred. End plate lengths were significantly shorter in the fibroblast growth factor 1-treated muscles (group 1) than in the specimens without fibroblast growth factor 1 (group 2) (31.2 vs 58.5 micron; P>001, paired t test). The arborization of motor end plates, rare extrasynaptic staining, and shorter end plate lengths seen in group 1 were all consistent with mature motor end plates. Controls (group 3) displayed limited motor end plate formation and extensive extrasynaptic staining typical of denervation. CONCLUSION: This study presents encouraging evidence that fibroblast growth factor 1 with fibrin adhesive carrier can facilitate the reinnervation of atrophied muscle by enhancing the formation or revitalization of motor end plates. Future studies will address muscle function and use of different carrier materials.

Animals↗
PubMed1995

Role of 5-hydroxytryptamine in toxaemia of pregnancy.

5-HT concentration in blood of 24 randomly selected pregnant women presenting with signs and symptoms of toxaemia of pregnancy were estimated and compared with 30 normal pregnant women. As such 5-HT level increases with the progress of pregnancy and in toxaemia group in comparison to normal pregnancy. A change in the degree of oedema from moderate to severe could bring a statistically significant change in blood pressure and serum 5-HT level. Increased 5-HT plays a role in toxaemia as well as in normal pregnancy and some of the toxic effects observed in toxaemia of pregnancy are due to the effects of 5-HT.

Adult↗
PubMed1994

Effect of lidocaine and quinidine on focal ventricular arrhythmias induced by subepicardial epinephrine in cats.

Subepicardial infusion of epinephrine (EP) in the dose of 3 x 10(-3) M in 2.5 x 10(-3)M CaCl2-0.9% NaCl (calcium-saline vehicle) at the rate of 10 microliters/min in the right ventricular myocardium of mongrel cats weighing between 2.7 and 3.3 kg produced uniform reversible and reproducible focal ventricular arrhythmias of varying intensity and duration. Infusion of two antiarrhythmic agents, lidocaine (LD) and quinidine (QD) in the same site of arrhythmogenesis in equimolar concentration of 3 x 10(-3) M along with EP in the same vehicle reduced incidence, duration, peak and mean frequencies of arrhythmias while the latent period of onset of arrhythmias increased significantly. In present study, quinidine, in equimolar concentration of 3 x 10(-3) M was found to be more effective than lidocaine in antagonizing EP-induced ventricular arrhythmias.

Animals↗
PubMed1991

Potentiation of cochlear hair cell loss by acoustic stimulus and gentamicin in the guinea pig.

We explored the possibility of synergism between a pure-tone stimulus and gentamicin in causing cochlear injury by analyzing hair cell loss. Guinea pigs receiving daily injections of gentamicin (200 mg/kg body wt.) for 1 week were exposed to a 2 kHz tone (95 dB SPL, 2 hours daily). Surface preparations of the spiral organ were studied by phase contrast microscopy, and the extent of hair cell loss in the entire organ of Corti was recorded in cytocochleograms. Gentamicin by itself was slightly ototoxic, damaging the innermost row of outer hair cells, whereas exposure to sound alone caused no hair cell loss. Combined antibiotic and acoustic exposure produced extensive cochlear damage. A few animals showed massive hair cell degeneration and collapse of the organ of Corti, except in the apical turn. The site of damage was possibly determined by the frequency of the sound stimulus. Thus, an intermittent tonal stimulus such as that used in the present experiment can be harmless by itself, but causes injury to cochlear hair cells in guinea pigs when administered in combination with gentamicin.

Acoustic Stimulation↗
PubMed1989

Influence of age on hair cell loss in the rabbit cochlea.

The surface preparation technique was used for a study of cochlear hair cell loss as a function of age in rabbits 1 week, 6 months, 1 year, and 4 years old. Cytocochleograms from these animals were prepared which indicated damaged or missing hair cells over the entire spiral organ from the apical to the basal coil. The loss in the mean percentage of total outer hair cells (OHC) and inner hair cells (IHC) appeared to increase linearly with increasing age, with a statistically significant correlation. The cell loss was similar in all three rows of OHC in each of the age groups. In animals up to 1 year of age, areas of OHC loss were localized in the apical and basal coils. In 4-year-old rabbits, OHC degeneration had become progressively accentuated and widespread. The pattern of IHC loss was somewhat similar to that of OHC. Age-related hair cell loss in the rabbit is comparable to that in the rat, monkey, and human cochlea.

Aging↗
PubMed1986

Age related cochlear toxicity from noise and antibiotics--a review.

Laboratory experimental evidence indicates that there is an age related susceptibility to cochlear damage from noise exposure and ototoxic antibiotics. In some rodents there is a critical period of auditory development during which there is greater vulnerability to such damage and, in some species, noise induced damage is influenced by genotype. Available data from patients are inconclusive in this regard. Further careful studies are indicated in this area. All available evidence emphasizes that caution should be exercised in the use of ototoxic drugs during pregnancy, in neonates, young children, and older people.

Acoustic Stimulation↗
PubMed1984

Ototoxicity and noise-drug interaction.

Diverse therapeutic agents, such as certain antibiotics, diuretics, and analgesics can cause functional and morphological damage to the inner ear. Noise present in recreational or occupational environment may also be potentially damaging to the auditory system when combined with some ototoxic therapeutic agents. This article documents recent research and controversies about the site and mechanism of action of major ototoxic drugs, noise-drug interaction, and possible prophylaxis against such ototoxicity.

Adult↗
PubMed1981

Distribution and structure of the adrenocortical homologue in the garpike.

The microanatomy of the yellow corpuscles (adrenocortical homologue, AH) in the holostean fish, Lepisosteus spp. was studied by serial sectioning, steroid histochemistry, and electron microscopy. The modification of this tissue to short-term ACTH treatment was also observed. The distribution of the AH within the renal tissue of the garpike phylogenetically represents a more advanced condition than that seen in its closest holostean relative, the bowfin, and appears to approximate that in teleosts. The homology of this tissue of vertebrate adrenocortical tissue was established by the positive identification of the enzyme, gamma 5-3 beta-hydroxysteroid dehydrogenase, and by the ultrastructural features of the cells before and after ACTH administration. The AH cells possess fine structural features characteristic of steroidogenic cells, namely, polymorphic mitochondria with tubular cristae, abundant tubules of smooth endoplasmic reticulum, a prominent Golgi complex, and lipid droplets. Other interesting features include the presence of annulate lamellae and a variety of dense bodies. Digitonin perfusion results in the deposition of presumed, cholesterol-digitonide crystalline spicules on the surface microplicae of the cells and as dense accumulations in association with smooth endoplasmic reticulum. ACTH administration results in swelling of mitochondria, a loss of their cristae, and a smooth decrease in electron density of their matrices. Alterations also occur in the smooth and rough endoplasmic reticulum, and large osmiophilic inclusions of irregular profile appear. Some of the ACTH-induced modifications are similar to those observed in the adrenocortical cells of other vertebrate groups following comparable stimulation.

3-Hydroxysteroid Dehydrogenases↗
PubMed1980

Ultrastructure of the adrenocortical homologue in dexamethasone-treated eels.

The ultrastructural modifications of the adrenocortical homologue (AH) in the North American eel (Anguilla rostrata) were studied following a 10 day treatment with dexamethasone (20 mg/day). The principal changes were: disorganization of smooth endoplasmic reticlum, regression and fragmentation of the Golgi apparatus, and a lowering of matrix density in the mitochondria. Steroid treatment also induced the appearance of numerous cytoplasmic inclusions: (a) lamellated bodies with electron-lucent cores; (b) membranous whorls isolating cytoplasmic regions containing smooth endoplasmic reticulum and mitochondria and (c) complex aggregates showing whorls of membranes, residues of cytoplasmic organelles, and dense matrix. The non-accumulation of lipid droplets in repressed AH cells was noteworthy. These subcellular changes indicate endogenous cellular autophagy in the AH as a result of steroid-induced suppression of ACTH production by the pituitary.

Adrenal Cortex↗