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Biomedical subjects

D D Jones

Publications and source records attributed to D D Jones.

At least 55 records · Page 3Linked to original sources
PubMed1977

Experimental study of sacculotomy in endolymphatic hydrops.

Thirty-nine guinea pigs were used for four groups of experiments: 1. sacculotomy only, 2. sacculotomy and simultaneous obliteration of the endolymphatic duct, 3. sacculotomy followed by obliteration of the endolymphatic duct, and 4. obliteration of the endolymphatic duct followed by sacculotomy. Sacculotomy alone caused only minimal cochlear pathology, whereas sacculotomy on hydropic ears produced severe atrophy of the organ of Corti and cochlear neurons as well as connective cells of the limbus. There was histological evidence that Reissner's membrane in hydropic ears was ruptured by the sacculotomy procedure. The primary cause for the severe atrophic changes is thought to be the toxic effect of intermixing perilymph with a large volume of endolymph. The surgically induced saccular tears appeared to be healed in all ears, and the procedure had no significant effect on the course of endolymphatic hydrops. Although two out of eleven specimens in which sacculotomy was performed on hydropic ears showed tears and collapse of Reissner's membrane, since others with similar tears showed extensive hydrops, the possibility of artifact could not be ruled out. In one specimen with simultaneous sacculotomy and obliteration of the duct, persisting fistulae were noted at the sites of accidental fracture of the osseous spiral lamina; this ear is the only one which failed to develop hydrops following obliteration of the duct. The results of this experiment, namely sacculotomy on hydropic guinea pig ears, suggest that sacculotomy is not a rational procedure for the control of endolymphatic hydrops in Ménière's disease for the following reasons: 1. surgically induced tears in the saccular wall are followed by rapid healing and 2. intermixing of perilymph and a large volume of endolymph causes toxic atrophy of the limbus, organ of Corti and cochlear neurons.

Animals↗
PubMed1977

Plasma urate and serum deoxycytidylate deaminase measurements for the early diagnosis of pre-eclampsia.

The value of measuring plasma urate and serum deoxycytidylate deaminase (dCMP deaminase) for the early diagnosis of pre-eclampsia has been investigated in 45 patients. A combination of increased blood pressure and increased plasma urate identified 19 patients with a high incidence of fetal and maternal morbidity ascribable to pre-eclampsia. Seventeen of the 19 patients also had an increased serum dCMP deaminase. Serial antenatal observations for a mean period of 104 days (36-179 days) on 33 of the patients demonstrated that plasma urate and serum dCMP deaminase increased together as early changes in the development of pre-eclampsia. In six patients, blood pressure, plasma urate and serum dCMP deaminase all increased but in only one was the rise in blood pressure the first change. Elevations of plasma urate and serum dCMP deaminase are therefore both early features of pre-eclampsia. Serial measurements can give warning of the disorder before the appearance of other clinical features. The change in dCMP deaminase is probably another reflection of early renal involvement in the pre-eclamptic process.

Blood Pressure↗
PubMed1977

The effect of metal ions on the activity of delta-aminolevulinic acid dehydratase.

The effects of lead, iron, copper, and zinc ions on delta-aminolevulinic acid dehydratase from red blood cell haemolysates in humans, both in the absence and presence of plasma proteins, have been investigated. delta-aminolevulinic acid dehydratase (ALAD) was not found to be a specific indicator of blood lead concentrations since it was also inhibited by copper and activated by zinc. Plasma protein protected the enzyme from both inhibition and activation. ALAD activity was found to be an indicator of the total metal ion concentration in the blood and was therefore considered to be of doubtful value in screening large populations for increased lead absorption.

Blood Proteins↗
PubMed1975

A rapid method for the determination of deoxycytidylate deaminase activity in pregnancy serum.

A method is described for determining the activity of deoxycytidylate deaminase in serum. The ammonia liberated from deoxycytidine monophosphate has been specifically determined by enzymatic amination of alpha-ketoglutarate using glutamate dehydrogenase. The concurrent oxidation of NADH2 at 340 nm was proportional to the ammonia liberated from deoxycytidine monophosphate. Using the technique described, a result would be available to the clinician in under 4.5 h. The "normal activity" for deoxycytidine deaminase in normal male, female and pregnancy sera has been determined.

DCMP Deaminase↗
PubMed1975

Deoxycytidylate deaminase in pregnancy.

Deoxycytidylate (DCMP) deaminase was assayed at various times during and after normal and abnormal pregnancies. The level in amniotic fluid was assessed at induction and at caesarean section, and cord blood levels were estimated after normal delivery and at caesarean section. A rise occurred during labour and after hysterectomy and caesarean section--returning to normal after 2-3, and 12 days respectively. Levels above 4.8 X 10-minus 4 ml-minus 1 were found in cases of preeclamptic toxaemia and early intrauterine death and in twin pregnancies over 36 weeks' gestation. It is suggested that because of its low incidence of false-negative and false-positive results this test is far superior to other enzyme tests in pregnancy, and a further trial is in progress to assess its role.

Aminohydrolases↗
PubMed1975

Source of the pregnancy serum N-acetyl-beta-glucosaminidase isoenzyme during human pregnancy.

The antisera to the A and B isoenzymes found in placenta and fetal liver were raised in rabbits. No antigenic difference was found between the fetal liver and adult tissue isoenzymes. Antisera to the placental isoenzymes did not react with the isoenzymes of adult tissues. The antibody raised against the placental B and fetal B liver isoenzyme decreased the N-acetyl-beta-glucosaminidase activity in maternal serum at 38 weeks gestation to the value found in normal human serum. Immunological evidence has been presented that the isoenzyme of N-acetyl-beta-glucosaminidase found only in pregnancy serum was of placental origin.

Acetylglucosaminidase↗
PubMed1975

The serum activity of glucose-6phosphatase and 5'-nucleotidase during human pregnancy.

An attempt has been made to show that the increase in enzyme activities in sera of pregnant women found with glucose-6-phosphate and adenosine 5'-monophosphate as substrates (described as glucose-6-phosphatase and 5'-nucleotidase) was due to the increase in alkaline phosphatase. The three enzyme activities has pH optima and heat stability characteristics of alkaline phosphatase. The response to the action of inhibitors and activators was typical for alkaline phosphatase. There was an identical increase in all three enzyme activities during pregnancy. As a control similar investigations were made with liver and placental tissue extracts.

Adenosine Monophosphate↗
PubMed1973

Blood lead levels in a Welsh rural community.

In a study of the blood lead levels of 626 healthy blood donors no differences were found between men and women, but there was a significant increase with age. Resident donors had a higher blood lead than students, and the level in residents increased with living in the Aberystwyth area up to about 20 years. The levels in the students did not increase with residence in Aberystwyth. No differences were found in the blood lead of donors living in different wards of Aberystwyth and none between the blood lead of donors living in the rural area and those in the town. Almost half of the local resident donors had a level above the "normal" range.

Adolescent↗