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Biomedical subjects

M Litt

Publications and source records attributed to M Litt.

At least 199 records · Page 11Linked to original sources
PubMed1977

Human cervical mucus. I. Rheologic characteristics.

The viscoelastic properties of human cervical mucus were subjected to detailed characterization by microrheometry. An introduced to the range of parameters that can be measured and the sensitivity of microroheometry to variations in mucus viscoelasticity was presented, along with an interpretation of results obtained by this approach. Fresh cervical mucus samples were shown to be rheologically heterogeneous, reflecting compositional differences in situ. Mucas viscoelasticity was stable for several hours when samples were stored at ambient temperature in the microrheometer sample holder. Mucus viscoelasticity was strongly dependent upon nondialyzable solids (NDS) concentration. In order to eliminate (NDS) as a variable in comparative studies of mucus, procedures were developed for reconstitution of mucus at identical (NDS) or for normalization of viscoelasticity data derived from fresh samples to 2.5% NDS. The validity of this approach was then examined by applying these procedures to mucus collected during the follicular, ovulatory, and luteal phases of the normal menstrual cycle.

Animals↗
PubMed1976

Effect of mucolytic agents on the rheological properties of tracheal mucus.

Canine tracheal mucus was dissolved by a number of mucolytic agents, including disulfide bond reducing agents, hydrogen bond breaking agents, and chaotropic ions, and their effect on rheological properties was assessed. Sodium thiocyanate led to 85-100% dissolution with the maximum retention of elasticity. Thiocyanate exposure did not result in demonstrable alterations in the size or shape of the mucus glycoproteins. Sodium thiocyanate is therefore recommended as a suitable dispersing agent for physiochemical studies of glycoprotein secretions.

Animals↗
PubMed1976

Biosynthesis of mammalian transfer RNA. Evidence for regulation by deacylated transfer RNA.

The rate of tRNA synthesis in cultured Friend leukemia cells has been examined as a function of the variation in polyribosome structure produced by treatment with a variety of inhibitors of protein synthesis. The results indicate, in contrast to the conclusions of Bölcsföldi (Bölcsföldi, G. (1974) Exp. Cell Res., 88, 231--240), that no necessary relationship exists between the ribosome distribution and the rate of tRNA synthesis. Alternatively, it is observed that inhibitors of tRNA aminoacylation cause, in all cases, a decrease in the rate of tRNA synthesis whereas drugs which may stimulate the aminoacylation of tRNA cause, in all cases, an elevation of the rate of tRNA synthesis. It is concluded that tRNA synthesis in mammalian cells may be regulated by the relative levels of acylated and deacylated tRNA.

Animals↗
PubMed1976

Neonatal narcotic abstinence: Effects of pharmacotherapeutic agents and maternal drug usage on nutritive sucking behavior.

An uncoordinated and ineffectual sucking reflex is a major manifestation of neonatal narcotic abstinence and may have important consequences for the infant's subsequent well being. Measures of nutritive sucking were used to monitor the severity of neonatal narcotic abstinence in a series of infants born to narcotic-dependent mothers who were either attending the methadone clinic or else were "street addicts." In all these infants, sucking measures were significantly reduced relative to normal control subjects. Furthermore, the sucking behavior of infants born to mothers attending the methadone clinic was significantly more depressed than that of infants born to street addicts. In regard to the salutary effects of pharmacotherapy for neonatal narcotic abstinence, infants treated with paregoric approached normal control levels and showed significantly better sucking than those treated with phenobarbital or diazepam. The latter drug practically eliminated all spontaneous nutritive sucking behavior.

Diazepam↗
PubMed1976

Studies in experimental eosinophilia. XI. Dependence of eosinophilia, apparently induced by histamine, on acidity.

A solution of histamine in saline elicited eosinophil response in both lymph nodes and the blood stream. The lymph node response was not inhibited by the antihistamine, mepyramine maleate, but was inhibited by puromycin. Both the lymph node and the systemic response were essentially abolished when the pH of the solution (5.0 and 4.7, respectively) was brought to neutrality by phosphate buffer. Serum could bring the pH of histamine to neutrality or higher, but the histamine-serum mixture retained in vivo activity, unless the histamine was buffered before addition to the serum. When normal guinea pig gamma-globulin was incubated with histamine, a nondialyzable factor was generated which had the same activity as histamine. Thirteen different amino acids induced lymph node eosinophilia and each was acid in saline solution; when one of them, trytophane, was brought to neutral pH, its activity was considerably reduced. During the period when the circulating level of eosinophils was rising, there was no detectable fall in the bone marrow stores of mature of immature eosinophils. Thus, the activity of histamine, vis-a-vis eosinophils, is nonspecific and is attributable to its acidity. The data suggest that histamine, in the acidic state, generates autoantigens, which, in turn, lead to antibody-mediated eosinophilia in lymph nodes.

Amino Acids↗
PubMed1976

Detection of cystic fibrosis heterozygotes using the zeta potential reduction method.

Parotid saliva samples from cystic fibrosis homozygotes, heterozygotes and normal individuals were tested by the zeta potential technique for secretion factor in a double-blind experiment. There was no overlap between zeta potential reduction of the control group and the cystic fibrosis test groups, indicating that the zeta potential test may be detecting a unique component in saliva of cystic fibrosis genotypes.

Adult↗
PubMed1975

The assessment of behavioral change in infants undergoing narcotic withdrawal: comparative data from clinical and objective methods.

Studies comparing objective measures of sucking with data from finegrained clinical assessments of the neonate have shown significant correlations between painstaking and time-comsuming clinical methods which may only be reliably applied by highly trained clinician-investigators, and the data generated by a simple technique which can be rapidly and precisely administered in the nursery by nurses or technicians. Within a few minutes the sucking instrument can generate data that explain 50% or more of the variance in certain relevant factors of the Brazelton neonatal neurobehavioral assessment scale, which in our hands requires the participation of two trained clinician-investigators for a period of almost one hour for each test and recording session. There are certain limitations to the information directly available from the sucking measures. Clinical observations must be made in order to correctly interpret some of the findings such as the biphasic relationship between irritability and sucking. For example, an infant may not suck at all because it is obtunded, or it may not suck because it is overexcited. In the case of irritability, sucking performance provides a measure of the magnitude, but not of the polarity of the CNS arousal sucking correlates directly and gives a good estimate of both polarity as well as amount of these behaviors. Objective measures of sucking behavior are a convenient and reliable means for measuring drug effects in the nursery and may be useful in regulating therapy of the newborn.

Arousal↗
PubMed1975

Narcotic addiction in the newborn: differences in behavior generated by methadone and heroin.

The nutritive sucking performance of congenitally addicted infants undergoing narcotic withdrawal was used to provide objective measures of adaptive behavior in a series of 50 infants born to mothers addicted either to heroin or methadone. Sucking rates as well as average pressures developed during sucking were significantly reduced for the addicted infants relative to a control group born to normal mothers and a second control group born to toxemic mothers. The subgroup of infants born to methadone-addicted mothers was significantly more depressed with regard to sucking behavior than the infants of heroin-addicted mothers. Furthermore, infants treated with paregoric (an opiate) for symptoms of the narcotic withdrawal syndrome showed significantly less depression of the sucking response than those treated with sedatives such as phenobarbital.

Adaptation, Physiological↗