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Biomedical subjects

J Desai

Publications and source records attributed to J Desai.

At least 19 recordsLinked to original sources
PubMed1997

Primary posterior capsulorhexis with and without anterior vitrectomy in congenital cataracts.

PURPOSE: To determine whether anterior vitrectomy is necessary along with primary posterior capsulorhexis in children less than 5 years of age with congenital cataracts. SETTING: Iladevi Cataract & IOL Research Centre, Ahmedabad, India. METHOD: This prospective study comprised 18 eyes of 16 children whose mean age was 2.3 years (range 3 months to 5 years). Primary posterior continuous curvilinear capsulorhexis (PCCC) and posterior chamber intraocular lens (IOL) implantation were performed in all eyes. No vitrectomy was done in 8 eyes (Group 1); an anterior vitrectomy was performed in 10 eyes (Group 2). Optic capture through the posterior capsule was achieved in 3 eyes in Group 1 and in 5 eyes in Group 2. Average follow-up was 13.3 months. RESULTS: Five eyes (62.5%) in Group 1 needed secondary pars plana vitrectomy because the visual axis was obscured; no eye in Group 2 needed a secondary procedure. Four Group 1 eyes developed significant complications (updrawn pupil, decentration, occlusio pupillae, transient glaucoma). While no Group 2 eye developed a serious complication, some degree of pigment dispersion was noted in all the eyes. CONCLUSION: The results suggest that anterior vitrectomy is desirable along with primary PCCC in children younger than 5 years with congenital cataracts.

Aphakia, Postcataract↗
PubMed1997

Enlarging the capsulorhexis.

We describe a method to enlarge an initial small capsulorhexis using an iris spatula and cystotome needle. The iris spatula is placed underneath the anterior capsulorhexis margin; the spatula supports the anterior capsule and protects the posterior capsule. A gentle touch on the spatula by the cystotome needle generates a break in the continuity. This is done prior to intraocular lens implantation with the capsular bag and anterior chamber filled with viscoelastic.

Anterior Chamber↗
PubMed1996

Long-term preservation of islets of Langerhans in hydrophilic macrobeads.

Several obstacles have hindered the successful transplantation of islets of Langerhans to human patients in efforts to cure type I diabetes mellitus. One problem is the necessity for short- and long-term storage of islets after isolation and before transplantation. Current long-term storage methods, such as incubation in a physiological medium and cryopreservation, are suboptimal, resulting in significant loss of viable islet mass or function. Better storage methods are needed. In this study we examined the long-term storage of rat islets in macrobeads composed of agarose and collagen. Islets isolated from Wistar-Furth rats were placed into macrobeads (1000 islets/macrobead) and maintained in culture for periods of up to 189 days at 37 degrees C. Insulin released from the cultured macrobeads remained constant for periods of at least 154 days. In one group, insulin release was 1050 mU/24 hr/4 beads on day 3 and 1040 mU/24 hr/4 beads on day 154. In another group, insuling release was 1305 Xenotransplantation of Wistar Furth islet macrobeads, stored for 10 to 112 days at 37 degrees C, degrees C into 42 B6AF/1 mice with streptozotocin-induced diabetes resulted in a return to euglycemia in the recipients within 24 hr. Thereafter, euglycemia was maintained for more than 100 days in 32/42 of the recipients, and removal of the macrobeads caused a return to hyperglycemia within 48 hr in all animals. In addition, a group of 7 mice receiving macrobeads containing 1000 islets stored for 84 days had normal glucose tolerance tests (compared with those of 7 nontreated, nontransplanted mice with streptozotocin-induced diabetes and 7 normal mice), demonstrating that the islets in the macrobeads were functioning as they would in an intact pancreas. Finally, 5 macrobeads transplanted after initial storage of 112 days, removed from the first recipient after 100 days or more, stored again for 4 days in vitro, and retransplanted into 5 other diabetic mice also restored and maintained euglycemia for at least 45 days. Our results indicate that collagen-agarose macrobeads are capable of preserving rat pancreatic islets for extended periods without loss of in vitro insulin release capability or ability to achieve and maintain euglycemia in vivo. As such they should be useful for human islet transplantation efforts.

Animals↗
PubMed1995

Capsulorhexis: its safe limits.

We undertook this study to determine the safe limits of capsulorhexis during nucleus expression in 40 eyes of patients undergoing extracapsular cataract extraction (ECCE) with a posterior chamber intraocular lens (PCIOL) implantation and in 30 cadaver eyes. In group I (patient eyes), capsulorhexis of 4.5 to 7.5 mm was performed and the nucleus was expressed by hydrodissection. The nuclei measured 4.5 to 9.0 mm. One relaxing incision at 12 o'clock position had to be placed in 9 patients. In group II (cadaver eyes), continuous curvilinear capsulotomies of 4.0, 4.5, 5.0, 5.5, 6.0 and 6.5 mm were made in 5 eyes each. No relaxing incisions were placed. In both the groups, nuclei of all sizes could be safely delivered through intact capsulotomies measuring 5.5 mm or more. In two patient eyes, posterior capsule rupture occurred with rhexis measuring 4.5 and 5.0 mm, respectively. In the cadaver eyes, intracapsular extraction occurred in 4 eyes with rhexis measuring 5.0 mm or less. We conclude that a rhexis less than 5.5 mm is not safe for nucleus delivery during ECCE.

Adult↗
PubMed1991

Acute hypokalemia and inducibility of ventricular tachyarrhythmia in a nonischemic canine model.

Inducibility of sustained ventricular tachycardia (VT) and ventricular fibrillation (VF) by programmed ventricular stimulation following acute hypokalemia was studied in 21 anesthetized dogs free of inducible ventricular tachyarrhythmias at baseline. The control mean serum potassium concentration of 3.65 mEq/L was decreased to 2.14 mEq/L by insulin and furosemide administration. Inducibility of arrhythmias was also assessed following isoproterenol infusion before and after induction of hypokalemia. None of the animals developed sustained VT. Only one animal developed VF following hypokalemia (p greater than 0.05). Two normokalemic animals and five hypokalemic animals developed VF following isoproterenol infusion; this difference was not significant (p greater than 0.05). In this study, hypokalemia did not predispose to the development of a substrate necessary for the genesis and maintenance of VT. The inducibility of VF following hypokalemia was not significantly enhanced and appears to be related to the "aggressive" stimulation protocol.

Acute Disease↗
PubMed1990

Impaired hoarding and olfactory learning in DSP-4-treated rats and control cagemates.

The possibility that variables affecting rats' home-cage odor preferences also influence hoarding behavior was examined. Neonatal male rats were injected SC with the noradrenergic neurotoxin, N-(2-chloroethyl)-N-ethyl-2-bromobenzylamine (DSP-4), or with vehicle. At weaning, rats were assigned to control-only, DSP-4-only, or mixed groups of DSP-4 and control rats. For the next 10 days, half the rats in each social condition were housed in cedar shavings, and remaining rats were housed in pine. Exposure to cedar significantly increased preference for the odor in control-only groups, but not in DSP-4-only or mixed treatment groups. Control-only groups also hoarded significantly more pellets per animal than rats in the other two social conditions. The results suggest that both olfactory adaptation and hoarding can be impaired by either neonatal NE depletion or an abnormal social environment.

Animals↗
PubMed1990

Characterisation of the gene encoding a 104-kilodalton microneme-rhoptry protein of Theileria parva.

A neutralizing antiserum, C16, raised against sporozoites of Theileria parva parva was used to screen a lambda gt11 expression library of T. parva parva (Muguga) genomic DNA fragments. Proteins encoded by one phage clone, lambda TpS-17, were reactive with the C16 antiserum. Detailed characterisation of the DNA insert showed it to encode determinants found on four theilerial antigens of approximately 104, 90, 85 and 35 kDa. The sequence encoded by the clone is expressed during sporogony as a single RNA transcript of about 3000 nucleotides. On sequencing a portion of the 5000-bp insert, an open reading frame of 2772 bp was revealed that encoded a 104-kDa protein. Immunoscreening a library of subfragments of the DNA insert with the original antiserum localised sequences encoding the dominant antigenic determinants to an 800-bp stretch of DNA at the 3' end of the open reading frame. Sequence data from three subclones spanning this region show portions of the antigenic domains to be unusually rich in proline residues which are repeated every three amino acids. These repeats often take the form X-S(T)-P or X-K(R)-P. Antibodies directed against each of the three subclones recognize the 104- and 35-kDa antigens and different combinations of the 90- and 85-kDa kDa antigens, suggesting that the smaller proteins are derived from the 104-kDa antigen by limited proteolysis occurring at the carboxyl terminus end of the protein. In immunoelectron micrographs the antigen is associated with the microneme/rhoptry complexes of the sporozoite.

Amino Acid Sequence↗
PubMed1990

Oesophageal resection after instrumental perforation.

Between 1981 and 1987, 11 patients underwent oesophageal resection following endoscopic perforation of the oesophagus. They had a median age of 67 years with a range of 36 to 88 years. They all were managed either by one- or two-stage oesophageal resections. Six patients were perforated at other hospitals, 5 on site. Seven had carcinoma of the middle or lower third of the oesophagus, 2 of these were perforated at attempted palliative intubation. Four had benign peptic strictures perforated during dilatation. Seven were resected within the first 24 hours and 4 between 2 and 10 days after perforation. All 4 patients with benign disease survived but 4 of the 7 patients with cancer died giving an operative mortality of 36.3%. Respiratory complications were the most common postoperative problem: all deaths were attributed to respiratory failure. Perforation of the thoracic oesophagus carries a high mortality. Resection after perforation in benign strictures may be life saving in a potentially lethal condition but resection after perforation, even in operable cancer, still carries a high mortality.

Adult↗
PubMed1989

Factors influencing mortality and morbidity following oesophageal resection.

Operative mortality and morbidity following oesophageal resection has fallen in recent years. We have attempted to identify the factors responsible for this improvement by reviewing the results of surgery at this hospital over the last 6 years. Two hundred and two oesophageal resections were performed between January 1981 and June 1987 for carcinoma. Of these, 21 patients (10.4%) died before leaving hospital. Fourteen patients died of multisystem failure, 1 died of pure respiratory failure and 2 died of renal failure. Two died of surgical causes (other than anastomotic leak), 1 died of pulmonary embolus and 1 from a cerebro-vascular accident. No patient died of purely cardiac causes. The most significant risk factors in those dying (Chi-square test) were: postoperative respiratory failure, defined as reventilation after initial successful extubation, (P less than or equal to 0.001), reoperation as an emergency in the early postoperative period (P less than or equal to 0.001), anastomotic leak (P less than or equal to 0.01) and age over 70 (P less than or equal to 0.005). Less significant risk factors were chyle leak and histologically undifferentiated tumour. Of the 181 survivors, 103 left hospital with no complications of any kind. The mean stay in hospital for survivors was 15 days. Respiratory infection occurred in 22% of patients, prolonged gastric stasis in 8%, wound infection in 5% and empyema in 1%. As long as high risk groups are accepted for radical surgery, operation will carry a significant mortality in those groups. In others, we believe that perioperative monitoring and early aggressive treatment of complications can further reduce mortality and morbidity.

Adenocarcinoma↗
PubMed1988

Infection rates in sterile males of morsitans, palpalis and fusca groups Glossina for pathogenic Trypanosoma species from East and West Africa.

Infection rates in sterile male Glossina morsitans centralis, G. austeni, G. palpalis palpalis, G.p. gambiensis, G. fuscipes fuscipes, G. tachinoides and G. brevipalpis for Trypanosoma vivax, T. congolense and T. brucei isolated from East and West Africa, were studied. Five groups of the sterile males, together with the five groups of sexually fertile males, of each of the respective species and subspecies were allowed to feed for 24 days on a Boran calf or goats infected with T. vivax or T. congolense, or with T. brucei for 34 days, after which they were dissected. The results showed that the infection of the pathogenic Trypanosoma species became better established in some tsetse species than in others. Also, the infection rates of T. vivax, T. congolense and T. brucei for sterile and sexually fertile males of any of the above Glossina did not differ significantly. These results indicate that releases of sterile male tsetse in the tsetse control programme will potentially increase the risk of trypanosomiasis during the period of tsetse releases in the affected areas, unless in the areas with low tsetse density the sterile male tsetse are rendered refractory to trypanosome infection prior to their releases while in the areas with medium to high tsetse densities, the resident tsetse populations are initially reduced with insecticides, traps and/or targets.

Africa, Eastern↗
PubMed1987

Comparative study on the infection rates of different Glossina species for East and West African Trypanosoma vivax stocks.

Teneral male Glossina morsitans centralis, G. austeni, G. palpalis palpalis, G. p. gambiensis, G. fuscipes fuscipes, G. tachinoides and G. brevipalpis were fed on the flanks of Boran calves infected with Trypanosoma vivax stock ILRAD 2241 isolated from a cow in Likoni, Kenya; stock ILRAD 2337 isolated from a cow in Galana, Kenya; stock ILRAD 1392 isolated from a cow in Nigeria; or, stock EATRO 1721 isolated from G. m. submorsitans in Nigeria. The tsetse were fed on the infected hosts for 24 days and were then dissected to determine the infection rates. In G. m. centralis and G. brevipalpis, the mature infection rates of T. vivax from Kenya were 61.1%, and 75.3% for ILRAD 2241, and 36.2% and 58.2% for ILRAD 2337, respectively. In G. austeni and in the four palpalis group of tsetse, the rates for these two stocks were very low and ranged from 0% in G. p. palpalis to 1.8% in G. austeni for ILRAD 2241 and from 0% in G. f. fuscipes to 5% in G. tachinoides for ILRAD 2337. In contrast, the hypopharyngeal infection rates of T. vivax from Nigeria were quite high in all the 7 tsetse species and sub-species. They ranged from 55.5% in G. austeni to 91.9% in G. p. gambiensis for ILRAD 1392, and from 71.4% in G. austenei to 97.1% in G. brevipalpis for EATRO 1721.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1982

Value of the H-Q interval in patients with bundle branch block and the role of prophylactic permanent pacing.

His bundle electrograms were obtained in 313 patients with chronic bundle branch block who were followed for a mean period of almost 3 years. The infranodal conduction time (H-Q interval) was less than 55 ms in 97 patients (Group I), 55 to 69 ms in 99 patients (Group II), and greater than or equal to 70 ms in 117 patients (Group III). There was a higher incidence of organic heart disease in patients in Group III, but the groups were otherwise comparable. On follow-up study, mortality and the incidence of sudden death were similar among the groups, but patients in Group III had a greater incidence of progression to high degree atrioventricular block (HDB) than did those in Groups I and II (14 of 117 [12%] versus 4 of 97 [4%] and 2 of 99 [2%], p less than 0.01, respectively). High degree block was found in 4 of 17 (24%) patients with an H-Q interval (H-Q) greater than or equal to 100 ms. Sixty-two patients underwent permanent prophylactic pacemaker insertion at the discretion of the referring physician and were compared with 231 patients who did not. Paced patients had a higher incidence of transient neurologic symptoms and prolonged H-Q, but the groups were otherwise comparable. On follow-up study, mortality and the incidence of sudden death were similar among the groups, but symptom relief was significantly more common among patients with pacemakers. In conclusion, in our population (1) H-Q greater than or equal to 70 ms was an independent risk factor for progression to HDB, (2) H-Q greater than or equal to 100 ms identified a subgroup at particularly high risk, and (3) prophylactic pacemakers relieved neurologic symptoms but did not prolong life.

Aged↗
PubMed1982

Termination of ventricular tachycardia by carotid sinus massage.

Intracardiac electrophysiologic studies were performed in two patients who had recurrent sustained ventricular tachycardia. In both, the tachycardia was repeatedly terminated by carotid massage. In one patient, intracardiac electrophysiologic studies revealed ventricular tachycardia with 2:1 retrograde ventriculoatrial (VA) block. Carotid massage resulted in alternate Wenckebach retrograde VA conduction terminated by ventricular echo beats. When ventricular echo beats occurred at a coupling interval of 340 - 400 msec, the tachycardia was terminated. Similarly, induced atrial depolarizations (during ventricular tachycardia) produced ventricular capture and terminated the tachycardia when the resultant ventricular coupling interval was 330 - 395 msec. In the second patient, progressively premature atrial or ventricular depolarizations did not terminate the tachycardia. carotid massage had no consistent effect on retrograde VA conduction during ventricular tachycardia, but usually resulted in gradual increases in the tachycardia cycle length (50 - 100 msec) before abrupt termination of the tachycardia. This is the first report documenting termination of ventricular tachycardia by carotid massage alone (i.e., without prior drug intervention); hence, tachycardia termination by simple carotid sinus massage does not prove a supraventricular origin. The mechanism of tachycardia termination was due to ventricular echo beats from retrograde atrioventricular nodal reentry in one patient and to direct vagal effects on either the ventricular muscle or the ventricular specialized conduction system in the other.

Adult↗
PubMed1982

Electrophysiologic effects of disopyramide in patients with atrioventricular nodal dysfunction.

Seventeen patients with first-degree or Mobitz I atrioventricular (AV) block and narrow QRS complexes underwent electrophysiologic drug testing before and after i.v. administration of disopyramide. Disopyramide did not significantly change the mean sinus cycle length (895 +/- 131 vs 877 +/- 119 msec), mean maximal sinus node recovery time (1134 +/- 160 vs 1133 +/- 13 msec), mean atrial effective refractory period (314 +/- 72 vs 307 +/- 54 msec), mean AV nodal conduction time (187 +/- 79 vs 180 +/- 73 msec) or the mean paced cycle length at which AV nodal Wenckebach conduction occurred (545 +/- 144 vs 497 +/- 130 msec) after disopyramide. The mean AV nodal effective refractory period decreased significantly (from 535 +/- 137 to 521 +/- 122 msec), and both infranodal conduction time and the paced ventricular cycle length producing ventriculoatrial block increased significantly (from 56 +/- 12 to 63 +/- 13 msec and from 625 +/- 158 to 655 +/- 157 msec, respectively). We conclude that i.v. disopyramide administered in a dose resulting in therapeutic blood levels showed no adverse effects on AV nodal conduction in patients with AV nodal dysfunction. In contrast, i.v. disopyramide depressed retrograde AV conduction.

Aged↗
PubMed1982

Disopyramide.

Since disopyramide was introduced 5 years ago, the therapeutic spectrum of this drug in treating patients with ventricular and atrial arrhythmias has been found to be similar to that of the other type I antiarrhythmic drugs, quinidine and procainamide. Disopyramide has the potential to suppress sinus node function and, therefore, must be used cautiously in patients with the sick sinus syndrome. The available data indicate that it can be used safely in patients with bundle branch block and first-degree or type I second-degree atrioventricular block. Disopyramide has been found at times to precipitate ventricular tachycardia or ventricular fibrillation. Because this drug often causes decompensation in patients with congestive heart failure, it must be used very cautiously, if at all, in such patients.

Arrhythmias, Cardiac↗