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Biomedical subjects

N S Desai

Publications and source records attributed to N S Desai.

At least 19 recordsLinked to original sources
PubMed2001

Active transport of nitrofurantoin into human milk.

STUDY OBJECTIVE: To determine the extent to which nitrofurantoin is transferred into human milk. DESIGN: Prospective, single-dose pharmacokinetic study. SETTING: University-affiliated clinical research center. PATIENTS: Four healthy lactating women 8-26 weeks postpartum. INTERVENTION: All subjects received a single, oral, 100-mg dose of nitrofurantoin macrocrystals with food. Serial serum and milk samples were obtained and analyzed by high-performance liquid chromatography. MEASUREMENTS AND MAIN RESULTS: Milk pH, milk fat partitioning, and protein binding in serum and milk were determined. Predicted milk:serum ratio (M:S) was compared with the observed M:S. Nitrofurantoin M:S predicted was 0.28+/-0.05, whereas M:S observed was 6.21+/-2.71. Average milk concentration was 1.3 mg/L, and estimated suckling infant dosage was 0.2 mg/kg/day or 6% of maternal dose (mg/kg). CONCLUSIONS: Nitrofurantoin is actively transported into human milk, achieving concentrations in milk greatly exceeding those in serum. Concern is warranted for suckling infants younger than 1 month old, or for infants with a high frequency of glucose-6-phosphate dehydrogenase deficiency or sensitivity to nitrofurantoin.

Administration, Oral↗
PubMed1999

Plasticity in the intrinsic excitability of cortical pyramidal neurons.

During learning and development, the level of synaptic input received by cortical neurons may change dramatically. Given a limited range of possible firing rates, how do neurons maintain responsiveness to both small and large synaptic inputs? We demonstrate that in response to changes in activity, cultured cortical pyramidal neurons regulate intrinsic excitability to promote stability in firing. Depriving pyramidal neurons of activity for two days increased sensitivity to current injection by selectively regulating voltage-dependent conductances. This suggests that one mechanism by which neurons maintain sensitivity to different levels of synaptic input is by altering the function relating current to firing rate.

Animals↗
PubMed1999

Housestaff workload and procedure frequency in the neonatal intensive care unit.

OBJECTIVE: To investigate the association of clinical workload and the decision to perform procedures on infants in the neonatal intensive care unit (NICU). DESIGN: Prospective cohort study over one academic year, observing infants exposed to housestaff working under various levels of clinical workload. SUBJECTS: All 31 housestaff rotating on the NICU service during the academic year 1993 to 1994 were observed. A total of 785 infants were admitted to these housestaff. SETTING: One academic Level III intensive care nursery. MEASUREMENTS AND MAIN RESULTS: Clinical workload was operationalized as number of NICU infants cared for by the individual houseofficer on-call each night. The procedures of interest were number of umbilical artery catheters (UACs), intubations, lumbar punctures (LPs), and peripheral phlebotomy performed by the houseofficer on-call. Using multiple linear regression approaches, controlling for the average severity-of-illness of each of the NICU infants, the experience and residency program of the houseofficer on-call, and the individual attending, we found that increased clinical workload (number of NICU infants) resulted in a significantly greater probability that an admitted infant received an umbilical artery catheter (p = .02), but resulted in less probability that any NICU infant received a lumbar puncture (p = .0001) or peripheral phlebotomy (p = .0002). The decision to intubate an infant was not affected by the workload in the NICU. CONCLUSIONS: The clinical workload of housestaff in the NICU can affect decisions to perform procedures on infants in the NICU. For equivalently severely ill infants, there is a greater chance of receiving a UAC and less chance of being phlebotomized or receiving an LP when workload is high. Attending neonatologists need to be sensitive to possible effects of workload on patient care in the NICU.

Analysis of Variance↗
PubMed1999

Two-color GFP expression system for C. elegans.

We describe the use of modified versions of the Aequora victoria green fluorescent protein (GFP) to simultaneously follow the expression and distribution of two different proteins in the nematode, Caenorhabditis elegans. A cyan-colored GFP derivative, designated CFP, contains amino acid (aa) substitutions Y66W, N146I, M153T and V163A relative to the original GFP sequence and is similar to the previously reported "W7" form. A yellow-shifted GFP derivative, designated YFP, contains aa substitutions S65G, V68A, S72A and T203Y and is similar to the previously described "I0C" variant. Coding regions for CFP and YFP were constructed in the context of a high-activity C. elegans expression system. Previously characterized promoters and localization signals have been used to express CFP and YFP in C. elegans. Filter sets designed to distinguish YFP and CFP fluorescence spectra allowed visualization of the two distinct forms of GFP in neurons and in muscle cells. A series of expression vectors carrying CFP and YFP have been constructed and are being made available to the scientific community.

Amino Acid Substitution↗
PubMed1998

Activity-dependent scaling of quantal amplitude in neocortical neurons.

Information is stored in neural circuits through long-lasting changes in synaptic strengths. Most studies of information storage have focused on mechanisms such as long-term potentiation and depression (LTP and LTD), in which synaptic strengths change in a synapse-specific manner. In contrast, little attention has been paid to mechanisms that regulate the total synaptic strength of a neuron. Here we describe a new form of synaptic plasticity that increases or decreases the strength of all of a neuron's synaptic inputs as a function of activity. Chronic blockade of cortical culture activity increased the amplitude of miniature excitatory postsynaptic currents (mEPSCs) without changing their kinetics. Conversely, blocking GABA (gamma-aminobutyric acid)-mediated inhibition initially raised firing rates, but over a 48-hour period mESPC amplitudes decreased and firing rates returned to close to control values. These changes were at least partly due to postsynaptic alterations in the response to glutamate, and apparently affected each synapse in proportion to its initial strength. Such 'synaptic scaling' may help to ensure that firing rates do not become saturated during developmental changes in the number and strength of synaptic inputs, as well as stabilizing synaptic strengths during Hebbian modification and facilitating competition between synapses.

2-Amino-5-phosphonovalerate↗
PubMed1998

The relevance of parity to ureteric dilatation.

OBJECTIVE: To assess whether the mild dilatation of the right ureter in women that is sometimes seen on intravenous urography (IVU) represents persistent dilatation after a previous pregnancy. PATIENTS AND METHODS: The intravenous urograms of 71 men, 63 parous and 27 nulliparous women were evaluated prospectively. The two groups of women were divided into those with and without a confirmed history of urinary tract infection (UTI) as the indication for IVU. producing five groups in all. Measurements were taken on both the 5-min and the compressed or release films on each side. RESULTS: There were no significant differences in ureteric diameters among the five groups for the uncompressed right ureter (P=0.23), the left ureter uncompressed (P=0.32) or compressed (P=0.87). For the compressed right ureter, the difference was significant, with the diameters in the parous women with proven UTIs being larger than in the other groups (P=0.043). CONCLUSION: There is a significant increase in the diameter of the compressed right ureter in the group of parous women with a history of proven UTI. Infection or parity alone do not produce this effect: the combination of the two factors is required.

Adult↗
PubMed1998

Occult spinal dysraphism in neonates: assessment of high-risk cutaneous stigmata on sonography.

OBJECTIVE: In this study, we evaluated the incidence of dorsal cutaneous stigmata in a healthy neonate population; we also assessed whether specific types of cutaneous stigmata are associated with underlying spinal dysraphism. SUBJECTS AND METHODS: From July 1993 through December 1996, we prospectively examined term neonates with dorsal cutaneous stigmata. Each neonate underwent spinal sonography and clinical assessment of the cutaneous stigmata. Incidence of dorsal cutaneous stigmata in a healthy neonatal population was determined by dividing the number of neonates with cutaneous stigmata by the total number of neonates examined. RESULTS: The incidence of cutaneous stigmata in the healthy neonate study population was 4.8%. We examined 207 neonates with 216 cutaneous stigmata, the most common of which was the simple midline dimple (74%). None of the neonates with only a simple midline dimple had spinal dysraphism. Of the 207 neonates we examined, 16 had spinal dysraphism. Clinical examination revealed 180 dimples and 36 other types of cutaneous stigmata (e.g., hemangiomas, hairy patches, masses, tails, lesions). Fourteen (39%) of 36 other cutaneous stigmata were positive for spinal dysraphism. Eight (40%) of 20 atypical dimples were positive for spinal dysraphism. Three were large clefts (>5 mm); the remaining five cases were seen in combination with other lesions and were all located more than 2.5 cm from the anus. Six (67%) of the nine neonates with multiple cutaneous stigmata had spinal dysraphism. CONCLUSION: Simple midline dimples are the most commonly encountered dorsal cutaneous stigmata in neonates and indicate low risk for spinal dysraphism. Only atypical dimples are associated with a high risk for spinal dysraphism, particularly those that are large (>5 mm), high on the back (>2.5 cm from the anus), or appear in combination with other lesions. High-risk cutaneous stigmata in neonates include hemangiomas, upraised lesions (i.e., masses, tails, and hairy patches), and multiple cutaneous stigmata.

Humans↗
PubMed1998

Neonatal alloimmune thrombocytopenia due to anti-HPA-1b (PLA2)(Zwb). A case report and review.

BACKGROUND: Neonatal alloimmune thrombocytopenia is a rare condition due to passively acquired maternal antibodies directed against paternal platelet antigens inherited by the infant. Only 5 cases have been reported due to antibodies against HPA-1b (PLA2) (Zwb). CASE REPORT: We report a case of neonatal alloimmune thrombocytopenia due to anti-HPA-1b in the second pregnancy of a 26-year-old Caucasian female. The male infant was treated with a 5-day course of intravenous immunoglobulin without complications. We report the HLA phenotype of the infant's mother and summarize the previous case reports due to anti-HPA-1b. CONCLUSION: Based on this case and a review of the literature, intravenous immunoglobulin as well as random donor exchange transfusion and random donor platelet transfusions are effective in the treatment of neonatal alloimmune thrombocytopenia due to anti-HPA-1b. Obvious associations between HLA alleles and sensitization to HPA-1b have not been elucidated.

Adult↗
PubMed1997

Does pediatric housestaff experience influence tests ordered for infants in the neonatal intensive care unit?

OBJECTIVE: To assess the relationship between the experience of pediatric housestaff and tests ordered on infants in the neonatal intensive care unit (ICU). DESIGN: Prospective, cohort study over one full academic year. SETTING: One academic Level III neonatal intensive care nursery. PATIENTS: Data were collected prospectively on all 785 infants admitted to the neonatal ICU from July 1993 to June 1994. These infants were cared for by 14 different categorical pediatric housestaff. MEASUREMENTS AND MAIN RESULTS: Our neonatal ICU has either a resident or an intern on-call by himself/herself at night, affording us a natural setting to compare intern vs. resident test ordering. The outcomes of interest were number of arterial blood gases, radiographs, and electrolytes ordered per infant by the on-call pediatric houseofficer, as tabulated the morning after the call night. Control variables included the severity-of-illness of the individual infant (using the Neonatal Therapeutic Intervention Scoring System), the workload of the houseofficer (number of patients, number of admissions), and supervision (rounding frequency and on-call attending). Controlling for the severity-of-illness of the infant, the workload on the call night, and supervision with multiple linear regression, we found that interns ordered significantly (p = .02) greater numbers of arterial blood gases per infant than residents, amounting to some 0.33 blood gases per infant per call night (3.22 vs. 2.89 arterial blood gases per infant per night). This increase of 0.33 blood gases per infant amounts to interns ordering $169 more arterial blood gases per call night at our institution. There was no difference between interns and residents in ordering radiographs or electrolytes. CONCLUSION: Interns order significantly more arterial blood gases per infant than junior and senior residents on-call in the neonatal ICU. Additional study is required to see if the experience of housestaff is associated with a broader array of neonatal outcomes, such as morbidity and mortality.

Blood Gas Analysis↗
PubMed1997

Relation of gastric distention to prostaglandin therapy in neonates.

PURPOSE: To evaluate the short-term gastric effects of prostaglandin therapy in neonates. MATERIALS AND METHODS: The authors retrospectively reviewed the radiographs of nine neonates with congenital heart disease who received prostaglandins during the 1st week of life. Eighteen matched control infants (nine healthy neonates and nine infants with noncyanotic congenital heart disease) who did not receive prostaglandins were also evaluated. RESULTS: Within 48 hours of initial prostaglandin therapy, persistent (>3 days) gastric distention was noted in four of nine infants. No infants developed feeding intolerance during the 1st week of life; two of nine infants (both with initial asymptomatic gastric distention) developed feeding intolerance with prolonged prostaglandin therapy. In all cases, gastric distention resolved with cessation of prostaglandins. The radiographs of the control infants were unremarkable (P < .01). CONCLUSION: Persistent, asymptomatic gastric distention can be seen in neonates within 48 hours of initiation of prostaglandin therapy. Intervention is not warranted; this finding resolves with cessation of prostaglandins. Early gastric distention may be predictive of feeding intolerance in infants who receive prolonged prostaglandin therapy.

Alprostadil↗
PubMed1997

Prognostic significance of tumor angiogenesis in advanced breast carcinoma: an Indian experience.

Angiogenesis is essential for tumor growth and metastasis. In the present study we investigated the prognostic significance of microvessels (MV) density using immunohisto-localization of factor VIII antigen in 51 breast cancer patients. We counted microvessels per 200x field in the most active areas of neovascularization by staining factor VIII related antigen and graded MV density and correlated with stage, LN involvement and histologic grade. Patients who subsequently developed metastases had significantly high MV counts than patients without metastatic disease (p < 0.001). Patients who subsequently died of the disease had significantly high mean microvessels counts than patients who remained alive at the end of 5 years (p < 0.001). As density of factor VIII antigen staining increased the survival decreased (p < 0.001). All the patients having > 25 MV per 200x field had tumor recurrence faster as compared with patients having < 25 MV (p < 0.02). Thus, the MV count correlates with the prediction for metastasis and poor survival. Such an indicator would be useful in selection of a subgroup of patients with breast cancer who are at high risk for having occult metastasis at presentation and subsequently would benefit from aggressive therapy.

Breast Neoplasms↗
PubMed1996

Housestaff experience, workload, and test ordering in a neonatal intensive care unit.

BACKGROUND: Little is known of how the inexperience or the clinical workload of housestaff affects the decisions they make in the neonatal intensive care unit (NICU). The authors hypothesized that less experienced interns would order more tests per infant than more experienced residents, especially under conditions of heavy workload. METHOD: The NICU at the University of Kentucky A. B. Chandler Medical Center has either an intern or a resident on call by himself or herself at night, a natural setting to compare test ordering by interns and residents. The authors counted the numbers of X rays, analyses of arterial blood gases (ABGs), and electrolyte determinations ordered by the house officers on call for 321 infants from July through November 1993. Data for nine interns and seven residents were compared using multivariate linear regression. RESULTS: When workload became heavier (about five NICU patients), the interns increased their ordering of ABGs per infant to a significantly greater degree than did the residents (p = .01), with the difference being even greater on weekends when the housestaff were under less supervision (p = .004). CONCLUSION: As workload becomes greater in the NICU, interns order more ABGs per infant than do more experienced residents, especially when the interns are less supervised.

Academic Medical Centers↗
PubMed1995

Occult spinal dysraphism in the infant.

The progressive neurologic dysfunction caused by occult spinal dysraphism can be prevented with early clinical recognition, radiographic diagnosis, and neurosurgical treatment. However, detection of occult spinal dysraphism in the infant is difficult because neurologic symptoms often are not apparent until the child becomes ambulatory. Occult spinal dysraphism, however, can be suspected in the asymptomatic neonate when cutaneous stigmata, such as hemangiomas, hairy patches, deep and/or eccentric dimples, or subcutaneous masses are seen over the lumbosacral spine. Because of the serious, often irreversible, sequelae of a delayed diagnosis, spinal sonography of high-risk infants with midline, lumbosacral, cutaneous stigmata should be considered as an effective, noninvasive screening method.

Humans↗
PubMed1991

Comparison of two neonatal intravenous amino acid formulations in preterm infants: a multicenter study.

Two neonatal intravenous amino acid solutions (Aminosyn-PF and Troph-Amine) were compared in 44 preterm infants. The rate of weight gain, nitrogen balance, and changes in plasma aminograms were determined over 7 days to ascertain whether different outcomes could be identified for the two solutions. At study entry, the infants received a minimum infusion of 2 g amino acid/kg/d with 50 or more nonprotein kcal/kg/d. Group mean amino acid intake over the study period was approximately 2.6 g/kg/d for both groups; nonprotein caloric intake approximated 90 kcal/kg/d. Results showed no significant differences between solutions for the rate of weight gain, nitrogen balance, and nitrogen retention, which approximated intrauterine rates. The rate of weight gain averaged nearly 15 g/kg/d for both solutions. Differences between day 0 and day 7 plasma aminograms showed significant changes between solutions for histidine, lysine, methionine, phenylalanine, threonine, and glutamic acid. However, day 7 plasma aminograms for both solutions compared favorably with those from enterally fed preterm infants reported in the literature. Failure to identify significant differences for the rate of weight gain, nitrogen balance, or nitrogen retention between the two groups suggests that differences in plasma aminograms resulting from use of one solution or the other had no short-term clinical consequences in the premature infants studied.

Amino Acids↗
PubMed1991

Purpura fulminans in three cases of early-onset neonatal group B streptococcal meningitis.

The diagnosis of purpura fulminans was associated with three cases of early-onset group B beta-hemolytic streptococcal (GBS) disease. All three infants had confirmed bacterial disease, extensive purpuric lesions involving the extremities, and laboratory evidence of a consumptive coagulopathy. All three children survived but had markedly compromised neurologic outcomes. Purpura fulminans has not been previously reported with early-onset GBS disease.

Disseminated Intravascular Coagulation↗
PubMed1986

Classroom performance and social factors of children with birth weights of 1,250 grams or less: follow-up at 5 to 8 years of age.

Of 43 long-term survivors with birth weights of 1,250 g or less, 33 were compared with peers and school-aged siblings for educational levels and needs. Of the 33 children in school, three (9.1%) were in classes for children with major handicaps, whereas 30 (90.9%) were found to be comparable to their classmates by teachers and/or test scores, but 14 (47%) were receiving remedial instruction to perform at grade level. Of 13 children with school-aged siblings, three required more hours of assistance by specialized teaching staff than their siblings. The group without the need for specialized teaching staff had older mothers and tended to reside in higher socioeconomic households. Overall, our children with birth weights of 1,250 g or less (51.5%) required more special education efforts than the general school population (24.1%), thereby enabling most to compare favorably with their peers.

Child↗
PubMed1983

Ischemic extremities due to compartment syndromes in a septic neonate.

The clinical presentation and diagnostic evaluation of a septic neonate with sclerema neonatorum and impending tissue loss secondary to compartment syndromes is presented. Vascular disease leading to tissue loss is uncommon in children. To our knowledge, this is the only reported case of a compartment syndrome leading to tissue loss in a neonate.

Compartment Syndromes↗