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Biomedical subjects

H Raj

Publications and source records attributed to H Raj.

10 recordsLinked to original sources
PubMed1995

Sensory origin of lobeline-induced sensations: a correlative study in man and cat.

1. Intravenous injections of lobeline HCl into twenty-six normal young male human volunteers produced sensations of choking, pressure or fumes in the throat and upper chest at a mean threshold dose of 12 micrograms kg-1. 2. Reflex changes in breathing pattern usually appeared just before the sensations. Increasing the dose of lobeline increased the intensity of the sensations gradually until a dry cough appeared at a mean threshold dose of 24.3 micrograms kg-1. At these doses there was a mean difference of 0.3s in the latencies for sensation and respiratory reflex; in four subjects there was no difference at all. 3. In cats anaesthetized with 35 mg kg-1 sodium pentobarbitone, injecting 25-67 micrograms kg-1 lobeline into the right atrium sensitized thirteen out of seventeen rapidly adapting receptors (RARs). In three out of four cats lobeline had no excitatory effect on the RARs in the absence of normal activity (i.e. when it was injected while artificial respiration was suspended), but on restarting the respiration the activity increased greatly. After injecting lobeline, the activity increased during inflation or deflation or in both phases of the respiratory cycle. It also increased greatly during deflation produced by suction of air from the lungs after lobeline. Such presumed increased activity in the RARs of man produced by forced expiration to residual volume at the time lobeline-induced sensations were expected did not enhance the sensations in any subject. 4. In all the subjects tested, forced expiration alone, which should stimulate RARs, never produced a dry cough or sensations similar to those produced by lobeline.(ABSTRACT TRUNCATED AT 250 WORDS)

Administration, Inhalation↗
PubMed1991

Hearing assessment by brainstem auditory evoked responses (BAER) in neonates at risk.

In the present study, brainstorm auditory evoked responses (BAER) were recorded in 68 at risk neonates discharged from the neonatal ICU of Safdarjung Hospital. The high risk group of 35 neonates included 13 neonates with multiple (3-4) risk factors and 22 neonates with single risk factors, viz., prematurity (less than 32 weeks) low birth weight (LBW) (less than 1500 g), hyperbilirubinemia requiring exchange transfusion, severe birth asphyxia, craniofacial malformations and sepsis with meningitis treated with amikacin for 3 weeks. The remaining 33 neonates were grouped in the low risk category who had only one of the following factors: prematurity (33-36 weeks)/LBW (1500-2000 g), hyperbilirubinemia requiring phototherapy, mild/moderate birth asphyxia, or sepsis treated with amikacin for 2 weeks. The test was performed at the mean conceptional age of 40.2 weeks (range 34-44 weeks) and involved determination of threshold of hearing as per presence of wave V. A normal response had wave V at 30 dB hearing level click stimulus at 50/sec from both ears or to 30 dB hearing level from one ear and 45 dB hearing level from the other ear. Thirteen neonates of the high risk group failed to produce a normal response (5 failed at 30 dB, 6 failed at 45 dB, and 2 failed at 75 dB hearing level). Forty six per cent of them had multiple high risk factors. All the low risk group neonates had normal threshold of 30 dB hearing level in the initial screening.(ABSTRACT TRUNCATED AT 250 WORDS)

Auditory Threshold↗
PubMed1991

Auditory brainstem response in neonates with hypoxic-ischemic-encephalopathy following perinatal asphyxia.

The technique of auditory brainstem evoked responses testing (ABR) was applied to twenty four new born infants with asphyxia complicated by hypoxic-ischemic-encephalopathy (HIE) in an attempt to study potential influence of HIE on hearing impairment. Twenty normal term neonates with no apparent neurological disorder, were also examined for comparison. Twenty two per cent (n = 5) of the patients with HIE showed some abnormality in the ABR pattern, the major one being a transient elevation in threshold of wave V (n = 4; 16.6%). ABR abnormalities, however, were found with greater frequency in neonates with Stage II HIE (75% vs 10%, p less than 0.001). Further ABR abnormalities were found in Stage II HIE only when duration of neurological abnormalities was greater than 5 days. There was no difference, however, between the ABR latencies of the asphyxiated and non-asphyxiated newborn infants (p greater than 0.05). One neonate (4%) with severe HIE, however, had persistent ABR abnormality in the form of bilateral absence of all waves in the later part of the ABR with preservation of wave I. This implied only cochlear functions and absence of any brainstem conduction. These results indicate that birth asphyxia complicated by HIE is a significant high risk factor for hearing impairment in the affected neonates. This justifies ABR testing of neonates with HIE (particularly Stage III), at the time of their discharge, as a screening procedure for early detection of permanent hearing loss.

Asphyxia Neonatorum↗
PubMed1966

Enrichment medium for selection of Salmonella from fish homogenate.

A new liquid medium, called "dulcitol selenite enrichment," has been developed for the detection and enumeration of Salmonella in foods. The medium is not only highly selective in enriching Salmonella and inhibiting completely or appreciably other extraneous organisms commonly found in seafoods, but is also highly sensitive in recovering as low as 2 to 7 cells of Salmonella, even in the presence of large numbers (10(4) to 10(6) cells) of mixed flora common to these foods. The addition of seafood material does not seem to interfere with the sensitivity, selectivity, or productivity of the medium. Even physiologically debilitated cells of Salmonella were enriched well enough in this medium to be detected easily.

Animals↗
PubMedDate not supplied

Auditory brainstem responses (ABR) in neonates with hyperbilirubinemia.

The technique of ABR testing was applied to 25 infants with neonatal hyperbilirubinemia at levels exceeding that for exchange transfusion, in an attempt to study potential influence of bilirubin toxicity on the auditory brainstem pathway. The test was performed at a mean conceptional age of 40.4 +/- 0.6 weeks just after discharge. Twenty normal term neonates of comparable birth weights and conceptional ages, who had no hyperbilirubinemia, were also examined for comparison. Fifty six percent (n = 14) of the hyperbilirubinemic neonates had some abnormality in the ABR pattern, the major one being a transient increase in the threshold of wave V (7, fail-30; 5, fail-45). Wave V, however, was consistently present at 30 dBnHL click stimulus in all the normal neonates (pass-30; normal threshold). Further, mean ABR latencies (wave III, V) and 1-V interpeak latency (brainstem conduction time) were significantly prolonged in jaundiced neonates as compared with controls (P less than 0.01). ABR changes were strongly correlated with the serum bilirubin levels (P less than 0.001). On follow up retesting at 3 months, however, all infants were found to have normal ABR latencies and threshold. Neonatal jaundice was associated with significant transient aberrations of ABR, suggestive of a transient toxic brainstem encephalopathy.

Auditory Threshold↗
PubMedDate not supplied

Evaluation of risk factors for hearing impairment in at risk neonates by brainstem evoked response audiometry (BERA).

Thirteen (19.2%) of 68 at risk neonates in an intensive care nursery with one or more adverse perinatal clinical factors viz; prematurity (less than 37 wks), low birth weight (less than 2000 gm), hyperbilirubinemia requiring active intervention, birth anoxia, neonatal seizures, infections, aminoglycoside administration, and craniofacial malformations; were diagnosed to have hearing impairment (elevated auditory threshold) by BERA testing performed within the first six weeks of life at a mean conceptional (gestational age + age after birth) age of 40.2 +/- 0.6 wks. As against this, 20 healthy term neonates who were examined at a mean conceptional age of 40.4 +/- 0.8 weeks had a normal hearing threshold of 30 db nHL. Elevated auditory threshold was found more frequently in neonates with multiple clinical adverse factors than in those having single risk factor (6/13 Vs 7/55, p less than 0.001). On multiple logistic regression analysis, however, only 2 factors viz; hyperbilirubinemia at level exceeding indication for exchange transfusion and birth weight less than 1500 gm, were found to be significantly correlated with the hearing impairment in the affected neonates and in that order of importance. Prematurity, birth asphyxia, neonatal seizures, infections and aminoglycoside administration had no significant correlation with hearing impairment. Since most of the neonates admitted to the neonatal ICU have one or more identified adverse risk factors, their hearing screening by BERA at the time of discharge seems justified.

Evoked Potentials, Auditory, Brain Stem↗