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Biomedical subjects

A Allen

Publications and source records attributed to A Allen.

At least 307 records · Page 17Linked to original sources
PubMed1980

Gastric mucus: isolation and polymeric structure of the undegraded glycoprotein: its breakdown by pepsin.

Human gastric mucus has been obtained from mucosal scrapings of gastric resection specimens. The glycoprotein was isolated from the mucus gel--undegraded and free of noncovalently bound protein--by equilibrium centrifugation in a CsCl density gradient. Ultracentrifugation studies showed this glycoprotein was a single component of molecular weight of 2 X 10(6). Analysis by gel filtration showed the undegraded glycoprotein was a polymer that was split into glycoprotein subunits, of about 5 X 10(5) mol wt, by pepsin and other proteolytic enzymes. Reduction with mercaptoethanol, but not with 2 M NaCl, also split the glycoprotein into subunits, which indicated that these subunits are joined together by disulphide bridges to form the undegraded glycoprotein. This structure is very similar to that described for the previously characterized pig gastric mucus glycoprotein, and it shows that results obtained using pig gastric mucus as a model are directly applicable to human gastric mucus. It also follows that pepsin in humans, by destroying this polymeric structure of the constituent glycoproteins, solubilizes the surface mucus gel, and liberates the degraded glycoprotein subunits into the gastric lumen. The relevance of this to changes in the thickness of the surface mucus gel in vivo and possible effects on mucosal protection in pathologic conditions is discussed.

Animals↗
PubMed1980

Attitudes toward weight gain in pregnancy.

Recently, there has been increased interest in the influence of maternal prenatal nutrition on the course and outcome of pregnancy. Evidence has accumulated that a woman's weight before pregnancy and the weight gained during pregnancy directly affect infant birth weight, incidence of neonatal mortality, and growth and development of the infant during the first year of life. Although recent recommendations for weight gain in pregnancy have been liberalized, a survey of 195 pregnant women who had prenatal visits in both clinic and private offices showed deficiencies in their understanding of the subject. Some 37 percent of women believed they should gain 20 pounds (9 kg) or less during pregnancy. Eight percent admitted to dieting before at least one antenatal visit and 54 percent thought their doctor would not be concerned about too little weight gained during pregnancy. This suggests that many women and some doctors are still ignorant of current concepts of proper nutrition during pregnancy. Apparently, increased lay and professional educational efforts are needed.

Attitude to Health↗
PubMed1979

Comparison of interwave latencies of brain stem auditory evoked responses in narcoleptics, primary insomniacs and normal controls.

A study of brain stem auditory evoked responses (BAER) was carried out in 10 narcoleptics, 10 primary insomniacs and 10 normal controls to determine if a neurophysiologic abnormality could be detected in these primary sleep disorders. The mean interpeak conduction times of Wave I-III, III-V and Iv were compared between the following groups: normal controls awake and in monitored sleep; narcoleptics awake and in monitored sleep, normal controls awake and narcoleptics awake; normal controls awake and insomniacs awake; narcoleptics awake and insomniacs awake; narcoleptics with cataplexy (n = 6) awake and narcoleptics without cataplexy (n = 4) awake. No significant differences were found which suggests that these sleep disorders represent dysfunctions which do not involve brain stem structures subserving the BAER.

Adult↗
PubMed1978

The isolation and characterization of the high-molecular-weight glycoprotein from pig colonic mucus.

1. A high-molecular-weight glycoprotein constitutes over 80% by weight of the total glycoprotein from water-soluble pig colonic mucus. 2. It was isolated from from nucleic acid and non-covalently bound protein by nuclease digestion followed by equilibrium centrifugation in a CsCl gradient. 3. The glycoprotein has the following composition by weight: fucose 10.4%; glucosamine 23.9%; galactosamine 8.3%; sialic acid 9.9%; galactose 20.8%; sulphate 3.0%; protein 13.3%; moisture about 10%. 4. The native glycoprotein has the high mol.wt. of 15 X 10(6). 5. Reduction of the native glycoprotein with 2-mercaptoethanol results in a glycoprotein of mol.wt. 6 X 10(6). 6. Pronase digestion removes 29% of the protein (3% of the glycoprotein) but none of the carbohydrate. 7. The molecular weight of the Pronase-digested glycoprotein is 1.5 X 10(6), which is halved to 0.76 X 10(6) on reduction with 2-mercaptoethanol. 8. The contribution of non-covalent interactions, disulphide bridges and the non-glycosylated peptide core to the quaternary structure of the glycoprotein are discussed and compared with the known structure of pig gastric glycoportein.

Amino Acids↗
PubMed1977

The action of proteolytic enzymes on the glycoprotein from pig gastric mucus.

A glycoprotein of mol.wt. 2x10(6) was isolated in homogeneous form from pig gastric mucus by isopycnic centrifugation in CsCl but without enzymic digestion or reductive cleavage of disulphide bonds. Digestion of the purified glycoprotein with trypsin, pepsin or Pronase resulted in the formation of glycoprotein subunits, of mol.wt. 5.2x10(5)-5.8x10(5), one-quarter that of the undigested glycoprotein. The glycoprotein subunits were isolated by gel filtration and shown to contain all the carbohydrate present in the undigested glycoprotein, but 18.6-25.6% of the total amino acids originally present were lost on digestion. The relative amount of threonine, serine and proline had increased from 41% (w/w) in the undigested glycoprotein to 61-67% of the total amino acids in the glycoprotein subunits after digestion. The results support the previously proposed structure for the glycoprotein, namely that of four subunits joined by disulphide bridges. These results show the presence of two distinct regions in the glycoprotein molecule, one rich in threonine, serine and proline, which is glycosylated and resistant to proteolyis, whereas the other, with an amino acid composition more characteristic of a globular protein, is not glycosylated and is susceptible to proteolysis. In addition, the region that is susceptible to proteolysis contains the disulphide bridges which join the glycoprotein subunits together to form the gastric glycoprotein.

Amino Acids↗
PubMed1977

A review of criminally insane patients in Ohio: a personal narrative.

In 1974, acting on precedents set in other cases, a federal district court in Ohio ordered the re-evaluation of all patients committed to Lima State Hospital to determine the need for their continuing to be held in a maximum-security facility. The court set a 12 week period for the review of more than 600 patients by three-member teams consisting of a psychiatrist, a psychologist, and a social worker. The author, a psychoanalyst, was one of approximately 30 professionals who volunteered to participate in the project, which was completed three weeks ahead of schedule. He describes the review process and his personal reactions and observations as a participant.

Commitment of Persons with Psychiatric Disorders↗
PubMed1976

Prenatal diagnosis of placental steroid sulfatase deficiency.

Placental steroid sulfatase deficiency is an unusual cause of low estriol production during pregnancy. Its importance lies in the differentiation of this disorder from the more ominous fetal defects that result in low estriol levels. Serum free estriol levels were found to be low or absent in a 25-year-old gravida 3, para 2 woman, while placental lactogen and chorionic gonadotropin levels were normal. An abdominal x-ray revealed no apparent congenital abnormalities and an oxytocin challenge test was negative. The dehydroepiandrosterone sulfate (DHEA-S) level in the patient's amniotic fluid was 6.8 to 18.4 times greater than those found in control amniotic fluids. The patient's amniotic fluid cortisol level was normal. Twenty-four hours following a normal, spontaneous labor and delivery at 39 weeks, the male infant underwent a synthetic ACTH1-24 stimulation test, with serum cortisols rising from 3.7 to 46 mug/dl at 1 hour. The placenta was morphologically normal on gross, light, and electron microscopic examinations. Steroid 3-alcohol sulfatase and arylsulfatase activities in the patient's placenta were virtually absent. These data indicate that this benign cause of low serum estriol levels may be diagnosed prenatally by elevated amniotic fluid DHEA-S levels.

Adult↗