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Biomedical subjects

P Deshpande

Publications and source records attributed to P Deshpande.

15 recordsLinked to original sources

Point mutant mice with hypersensitive alpha 4 nicotinic receptors show dopaminergic deficits and increased anxiety.

Knock-in mice were generated that harbored a leucine-to-serine mutation in the alpha4 nicotinic receptor near the gate in the channel pore. Mice with intact expression of this hypersensitive receptor display dominant neonatal lethality. These mice have a severe deficit of dopaminergic neurons in the substantia nigra, possibly because the hypersensitive receptors are continuously activated by normal extracellular choline concentrations. A strain that retains the neo selection cassette in an intron has reduced expression of the hypersensitive receptor and is viable and fertile. The viable mice display increased anxiety, poor motor learning, excessive ambulation that is eliminated by very low levels of nicotine, and a reduction of nigrostriatal dopaminergic function upon aging. These knock-in mice provide useful insights into the pathophysiology of sustained nicotinic receptor activation and may provide a model for Parkinson's disease.

Animals↗

Prenatal diagnosis of fetal abdominal lymphangioma by ultrasonography.

We present a case of abdominal lymphangioma in a fetus together with a review of the literature. Diagnosis was made at 20 weeks' gestation by antenatal ultrasonography. In keeping with other reports, the lesion was located on the left and serial ultrasonography demonstrated rapid growth with extension into the lower extremity.

Abdominal Neoplasms↗

Using active management of labor and vaginal birth after previous cesarean delivery to lower cesarean delivery rates: aA 10-year experience.

OBJECTIVE: Our objective was to analyze the statistics on cesarean delivery rates and the factors that have led to a reduction in these rates. STUDY DESIGN: A retrospective analysis was done of delivery statistics from a 10-year period, January 1, 1989, to December 31, 1998. We investigated the changes made in the methods of delivery during the study period. The data were divided into 1-year periods and analyzed by chi(2) tables. RESULTS: The overall cesarean delivery rate decreased from 16.59% to 10.92%; the primary cesarean delivery rate decreased from 9.22% to 7.11% and the repeated cesarean delivery rate from 7.37% to 3.81%. All these decreases were statistically significant. An increase in the rate of active management of labor by increasing oxytocin use and encouraging a trial of labor after previous cesarean delivery was also statistically significant. No changes in the outcome were observed in terms of neonatal morbidity and mortality rates. CONCLUSION: We found that our working plan for management of labor and delivery yielded and maintained a successful decline in the cesarean delivery rates without any negative effect on neonatal or maternal mortality rates. This low rate was maintained for a 10-year period.

Adult↗

Failure of autoresuscitation in weanling mice: significance of cardiac glycogen and heart rate regulation.

"Autoresuscitation" (AR) is the spontaneous recovery from hypoxic apnea by gasping. We examined aspects of heart function in two situations: 1) the maturationally acquired failure of AR that is characteristic of SWR, but not BALB/c, weanling mice and 2) AR failure in BALB/c mice induced by repeated exposures to anoxia. We determined maturational changes in heart and liver glycogen. Unlike liver glycogen levels, heart glycogen levels in SWR mice differed from those in BALB/c mice. They were consistently much lower throughout maturation and reached a nadir during the brief period when SWR weanling mice are vulnerable to AR failure. Also, rate of cardiac glycogen utilization in vulnerable SWR mice was lower than that of same-aged BALB/c mice and was nil during the latter one-half of the gasping stage when heart function is critical for AR success. Therefore, because glycogen utilization reflects cardiac work, heart failure could explain AR failure in SWR weanlings. Additionally, the increase in hypoxic heart rate that occurs with maturation is developmentally delayed in SWR mice, and this may contribute to their AR failure. Cardiac glycogen was not fully depleted in BALB/c mice during repeated anoxic exposures, indicating other reasons for AR failure. We view these findings as a potential model for the age-related peak in incidence of sudden infant death syndrome.

Age Factors↗

Channel gating governed symmetrically by conserved leucine residues in the M2 domain of nicotinic receptors.

In nicotinic acetylcholine receptors (nAChR), as well as glycine, GABAA (gamma-aminobutyric acid), serotonin (5-HT3), and GluCl glutamate receptors, a leucine residue at the approximate midpoint of the M2 transmembrane domain (the 9' position) is conserved across most known subunits. Structural data for the nAChR suggest that the Leu 9' residues occupy a 'kink' in each of the five M2 helices and point into the closed channel; in the opening step, the M2 helices rotate so that Leu 9' side chains no longer occlude the conduction pathway. Mutation of Leu 9' to one of several other residues slows desensitization and increases sensitivity to agonist. We have exploited the alpha 2 beta gamma delta stoichiometry of muscle nAChR to express receptors with ms* = 0 to 5 Leu 9'Ser mutated subunits. Strikingly, each Leu 9'Ser mutation shifts the dose-response relation for ACh to the left by approximately 10-fold; a nAChR with ms* = 4 is 10(4)-fold more sensitive than the wild type. The results suggest that each of the five Leu 9' residues participates independently and symmetrically in a key step in the structural transition between the closed and open states.

Acetylcholine↗

DMSO resolves certain compressions and signal dropouts in fluorescent dye labeled primer-based DNA sequencing reactions.

Automated base calling algorithms are more sensitive to the quality of the DNA sequencing data than are the labor intensive visual methods of base calling. To improve this quality, data from DNA sequencing reactions have been compared in order to determine the effects of the inclusion of dimethyl sulfoxide (DMSO). Inclusion of 10% DMSO into the reaction cocktail resolves at least one type of sequence compression. This compression may be due to the lack of ability in T7 DNA polymerase to read through certain sequences correctly. The poor quality of these data is seen as radioactive bands or fluorescent signal peaks that have an abnormal alignment, either in the wrong order or as single bands/peaks. The inclusion of DMSO also resolves sequences where the peak signal is absent or severely diminished, leading to a "gap" in the chromatogram profile. DMSO is better than deaza-dITP for resolving certain compressions. Addition of DMSO is a cheaper and more efficient method for high-throughput DNA sequencing than repeating reactions with base analogs.

Algorithms↗

Organization, sequence, and function of 34.5 kb of genomic DNA encompassing several murine T-cell receptor alpha/delta variable gene segments.

A cosmid-bearing murine genomic DNA, encompassing several T-cell receptor variable alpha/delta gene segments, has been sequenced using shotgun DNA cloning methodology coupled with fluorescence-based high-through-put DNA sequencing technology. This region, spanning 34.5 kb, contains a pseudogene V alpha gene segment (psi V alpha 16.1), a V delta gene segment (V delta 2), and a variable gene segment that has been reported to be expressed with both C alpha (V alpha 6) and C delta (V delta 3). Therefore, this cosmid is the ideal vehicle for examining the possible control sequences that may be involved in determining whether a V gene segment associates with either C alpha or C delta. Polymerase chain reaction experiments demonstrate that the two functional variable gene segments (V delta and V alpha/delta) are expressed individually with both C alpha and C delta genes as mRNA, indicating a permissiveness in their expression patterns. In addition, a variety of genomic sequence-related features have been identified.

Amino Acid Sequence↗

The human T-cell receptor TCRAC/TCRDC (C alpha/C delta) region: organization, sequence, and evolution of 97.6 kb of DNA.

We sequenced and analyzed 97.6 kb of new DNA sequence containing the human TCRAC (C alpha) and TCRDC (C delta) genes as well as the TCRDV3 (V delta 3) and 61 different TCRAJ (J alpha) gene segments and compared its organization and structure to the previously described mouse T-cell receptor TCRAC/TCRDC (C alpha/C delta) region. A comprehensive nomenclature, consistent with the IUIS nomenclature committee recommendations, for both human and mouse TCRAJ gene segments is presented. In the human sequence, we identified 20 new TCRAJ gene segments and obtained the germline sequence for 23 additional TCRAJ gene segments known from cDNA clones. Using the sequence data obtained from the human TCRAC/TCRDC region, we have extended a polymerase chain reaction-based assay to test for the expression of the individual TCRAJ gene segments. At least five TCRAJ pseudogene segments were identified by sequence criteria. Like the murine TCRAC/TCRDC sequence, this sequence contains a high level of coding sequence, with over 6.6% of the total sequence being transcribed. Comparison of the human sequence with the previously reported mouse DNA sequence reveals homologous counterparts for the variable and joining (J) gene segments and both constant genes. Eleven new J pseudogene segments have been identified in the mouse TCRAC/TCRDC sequence through the use of human and mouse sequence comparisons. In terms of structure and organization, this region of the human and mouse genome appears to be remarkably conserved.

Amino Acid Sequence↗

Sequence length and error analysis of Sequenase and automated Taq cycle sequencing methods.

We have examined DNA sequence error as a function of length using both a manual method of performing reactions with Sequenase and an automated Taq cycle sequencing method. DNA fragments from both methods were separated and analyzed on a sequencer. To determine the sequence of a cosmid insert (35.3 kb), 379 sequences were obtained from a manual Sequenase method, and 354 sequences were obtained from a Taq cycle sequencing method as performed on an automated robotic workstation and sequenced on an automated fluorescent sequencer. A highly redundant consensus of these sequences was obtained and aligned with the individual sequences to determine sequence error over the length of each sequence. The results of this study indicate that error is about 1% per position over the first 350 nucleotides, but increases thereafter to about 17% at 500 nucleotides. This pattern of accuracy was nearly equivalent for manual Sequenase methods and automated Taq cycle sequencing methods. The potential of these methods in large-scale DNA sequencing projects is discussed.

Cloning, Molecular↗

Effect of azadirachtin on Mesocyclops leuckarti sensu lato, vector of dracunculiasis.

Extension or otherwise of characteristic insect development inhibitory effects of the neem sesquiterpenoid azadirachtin have been examined on eggs and nauplii of the crustacean cyclops, M. leuckarti sensu lato, a major vector of guineaworm disease at 0.1 ppm and above doses. Azadirachtin reduced survival of early nauplii (N1 to N3) at 0.1 ppm and above doses. No such effect was observed when eggs and late nauplii (N4 to N5) were exposed. Azadirachtin did not affect the moult cycle when late nauplii (N4 to N5) were exposed continuously till adulthood. At all concentrations tested, adult cyclops exhibited normal mating.

Animals↗

Soleus motor neuron excitability before and after standing.

H-reflexes have been used to assess the effect of various postures on the excitability of the soleus motor neuronal pool. The purpose of this study was to determine if the excitability of the motor neuron pool, measured via H-reflexes in a seated position, change after a standing protocol in able-bodied individuals. We hypothesized that the excitability of the motor neuronal pool is minimally affected by the standing protocol leading to a reproducible H-reflex. Ten healthy individuals (height = 69.05+/-2.27 inches, weight = 161.7+/-22.44 lbs, age = 27.7+/-7.0 years) participated in the study. Soleus H-reflex recruitment curves were established before and after a standing protocol in a seated position. The standing protocol involved 12 minutes of active upright standing interspersed with 10 minutes of relaxed passive standing in a standing frame, similar to a protocol currently used for spinal cord injured subjects. The maximum M-waves and H-reflex amplitudes were not systematically changed before and after standing. There was also a strong agreement between the H-reflexes and M-waves measured before and after standing (ICC = 0. 99 and .96, respectively). We conclude that the H-reflexes measured in this study were reproducible, indicating that standing had no long lasting effect on the motor neuronal pool excitability. The findings support that the method discussed in this report is appropriate to assess the effects of electrically induced standing on motor neuron pool excitability in individuals with spasticity from spinal cord injury.

Adult↗