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Biomedical subjects

J Myers

Publications and source records attributed to J Myers.

At least 217 records · Page 12Linked to original sources
PubMed1984

Alpha 1-acid glycoprotein and albumin in human serum bupivacaine binding.

Bupivacaine protein binding was studied with the use of human serum, isolated human serum albumin, and isolated alpha 1-acid glycoprotein. The effect of lactic acid on bupivacaine binding was also studied. Bupivacaine protein binding in serum is best characterized by a model described by two classes of binding sites and that in alpha 1-acid glycoprotein or albumin is best characterized by a model described by one class of binding sites for each protein. Albumin binding closely correlated with the data obtained for the low-affinity, high-capacity binding site in serum, while alpha 1-acid glycoprotein data closely correlated with the data obtained for the high-affinity, low-capacity site in serum. A reduction in pH resulted in a significant reduction in the affinity for the high-affinity, low-capacity site in serum. No other binding parameters were affected. These data were in excellent agreement with results of the isolated protein studies. Our data demonstrate that acidosis results in significant increases in free bupivacaine concentrations only at relatively low total bupivacaine concentrations (less than 7 micrograms/ml) and that distribution characteristics for bupivacaine are essentially unchanged over a wide concentration range.

Bupivacaine↗
PubMed1984

The role of sodium and potassium in the control of blood pressure.

When sodium intake was increased from 70-200 mmol/day in normotensive volunteers, their blood pressure rose by 6/4 mmHg. In most people over 50 years, blood pressure rose and it also rose in about 15% of younger people. Those who had a rise in blood pressure had a creatinine clearance lower than others when on a reduced sodium intake. In the sodium sensitive group creatinine clearance rose when sodium intake was increased. In the people with a rise in blood pressure there was a fall in plasma volume. Increased sodium intake altered a number of factors that control sodium transport across cell membranes. The changes are complex but suggest that genetically inherited and environmentally caused defects are necessary to allow hypertension to be expressed. Reduction of sodium intake reduced blood pressure in people with mild hypertension. Potassium interacted with sodium to reduce the rise in blood pressure caused by sodium. Sodium intake and blood pressure are linked by many mechanisms. If the intake is excessive for that individual or if there are defective control mechanisms, hypertension will result.

Age Factors↗
PubMed1984

The reproducibility of hemodynamic, electrocardiographic, and gas exchange data during treadmill exercise in patients with stable angina pectoris.

Fourteen male patients with exercise test-induced angina and ST-segment depression underwent treadmill testing on three consecutive days to evaluate the reproducibility of certain treadmill variables. Computerized ST-segment analysis and expired gas analysis, including anaerobic threshold, were evaluated for reproducibility using an intra-class correlation coefficient analysis. Measured oxygen uptake at peak exercise displayed better reproducibility than total treadmill time, the onset of angina, and the gas exchange anaerobic threshold (ATGE). The double product, heart rate, and ST-segment displacement in lead X were found to be reproducible at peak exercise, the onset of angina, and the ATGE. The incorporation of gas exchange analysis can provide accurate physiologic determinants of exercise capacity in patients with angina pectoris. In addition, noninvasive estimates of myocardial oxygen demand and ischemia can be reproducibly determined. These findings have important implications for the design of studies evaluating the effects of an intervention on angina pectoris.

Adult↗
PubMed1984

The role of potassium in control of blood pressure.

Extra potassium intake has been found to be a determinant of blood pressure for epidemiological and experimental reasons. People with hypertension have a small fall in blood pressure with added potassium. Potassium chloride (48 mmol/day) was given to 36 male patients with high blood pressure; 5 did not comply with therapy. In the entire group of patients, potassium chloride had no significant effect on blood pressure, but prevented the rise in blood pressure and pulse rate produced by posture. In patients with a urinary Na+ excretion less than 75 mmol per 10 mmol creatinine, potassium chloride had no effect on supine blood pressure, but prevented the rise in blood pressure and pulse rate with standing. In those on a high sodium intake, potassium chloride lowered both the systolic and diastolic pressures. In sodium-responsive subjects, potassium chloride prevented the rise in blood pressure induced by sodium chloride but had no significant effect on blood pressure when on a low sodium intake. These results indicate that potassium reduces the rise in blood pressure caused by sodium chloride and reduces the increased sympathetic postural response seen in people on a low sodium intake.

Aged↗
PubMed1983

Phycobilisome composition and possible relationship to reaction centers.

The photosynthetic apparatus was studied in Anacystis nidulans wild type and in a spontaneous pigment mutant 85Y which had improved growth in far-red light (greater than 650 nm). Two phycobiliproteins, C-phycocyanin (lambda max 625) and allophycocyanin (lambda max 650), were present in a molar ratio of approximately 3:1 in the wild type and approximately 0.4:1 in the mutant. Phycobilisomes of wild type cells were larger (57 X 30 nm) than those of the mutant 85Y (28 X 15 nm). In the mutant they seemed to consist primarily of the allophycocyanin core. Fluorescence emission maxima of wild type and mutant 85Y phycobilisomes were at 680 nm (23 degrees C) and 685 nm (-196 degrees C). Excitation maxima of phycobilisomes were at 630 and 650 nm for the wild type and the mutant 85Y, respectively. The phycobilisomes of wild type cells whether grown in white or far-red light had the same size and pigment composition. A typical wild type cell in white light had a thylakoid area of 22.8 microns 2, but in far-red light the area was reduced to 13.5 microns 2, which was close to that of 85Y at 13.6 microns 2. Chlorophyll molecules per cell decreased in far-red light from 1.1 X 10(7) in wild type (white light) to 4.5 X 10(6) in mutant 85Y (far-red). The number of phycobilisomes per cell (approx 2 X 10(4)), calculated from the phycobiliprotein content and phycobilisome size, was about the same in wild type (white light) and mutant 85Y (far-red light), but the number of phycobilisomes per unit area of thylakoid was significantly greater in mutant 85Y than in wild type. The present results suggest that the phycobilisomes are linked with reaction centers and that the PSII complement (photo-system II and phycobilisome) was fully maintained in far-red light.

Binding Sites↗
PubMed1983

Synthesis of a shortened pro-alpha 2(I) chain and decreased synthesis of pro-alpha 2(I) chains in a proband with osteogenesis imperfecta.

Synthesis of type I procollagen was examined in skin fibroblasts from a proband with a lethal variant of osteogenesis imperfecta. The fibroblasts synthesized shortened pro-alpha 2(I) chains and these shortened chains accounted for all the pro-alpha 2(I) chains synthesized by the cells. In addition, there was a decrease in the relative rate of synthesis of pro-alpha 2(I) chains. Fragmentation of the shortened pro-alpha 2(I) chains with vertebrate collagenase and cyanogen bromide demonstrated that the shortening was in alpha 2(I)-CB3,5A, a fragment from about the middle of the chain containing amino acid residues 361 to 775. Based on the relative mobility in electrophoretic gels, the shortening was about 20 amino acid residues. The decreased synthesis of pro-alpha 2(I) chains was demonstrated by an increase in the ratio for the rates of synthesis of pro-alpha 1(I):pro-alpha 2(I) chains. It was associated with an increase in the ratio of mRNAs for pro-alpha 1(I):pro-alpha 2(I) in the cells. Fibroblasts from the father also demonstrated a decreased synthesis of pro-alpha 2(I) chains as reflected by an increase in the ratio of newly synthesized pro-alpha 1(I):pro-alpha 2(I) chains. No shortened pro-alpha 2(I) chains were seen in fibroblasts from either the father or the mother. The observations suggested that the proband inherited a nonfunctioning pro-alpha 2(I) gene from her father and that the gene for the shortened pro-alpha 2(I) chain probably arose from a sporadic mutation.

Cells, Cultured↗
PubMed1983

Combination chemotherapy for the treatment of Hodgkin's disease in relapse. Results with lomustine (CCNU), melphalan (Alkeran), and vindesine (DVA) alone (CAD) and in alternation with MOPP and doxorubicin (Adriamycin), bleomycin, and vinblastine (ABV).

Vindesine (desacetyl vinblastine amide sulfate, DVA) was used in combination with CCNU (lomustine) and melphalan (Alkeran) (CAD) to treat 15 heavily pretreated patients with Hodgkin's disease in relapse. The patients were treated with up to six cycles, depending upon their response. Two patients (13%) achieved a complete remission (CR) and five (33%) patients a partial remission (PR). The major toxicity was prolonged thrombocytopenia, which was decreased by a reduction in the initial drug doses for patients who had received extensive prior chemotherapy and radiotherapy (RT). The CAD regimen was then alternated with nitrogen mustard or cyclophosphamide, vincristine, procarbazine, and prednisone (MOPP, C-MOPP) and doxorubicin (Adriamycin), bleomycin, and vinblastine (ABV) for a total of nine cycles in 25 patients with Hodgkin's disease in relapse with somewhat more favorable prognostic features. Two patients also received low-dose RT to areas of bulky nodal disease. Eleven patients (44%) achieved a CR and seven (28%) a PR. Of the 11 CR patients, six remain in remission. The serious toxicity was comparable to that seen with other combination chemotherapy regimens. These results indicated that the CAD/MOPP/ABVD regimen is as active as other so-called 'salvage' regimens for Hodgkin's disease in relapse, and suggest that it might be useful for newly diagnosed Hodgkin's disease.

Adolescent↗
PubMed1983

Inherited deficiency of C8 in a patient with recurrent meningococcal infections: further evidence for a dysfunctional C8 molecule and nonlinkage to the HLA system.

An adult male with recurrent meningococcal infections is reported whose serum lacked functional C8 activity but possessed antigenic C8. The addition of 1500 U of purified C8/ml of serum restored hemolytic activity to normal. Four to five times more C8 was required to restore bactericidal activity than to restore hemolytic activity. Bactericidal activity could also be restored by mixing the patient's serum with a second C8-deficient serum that lacked detectable antigenic or functional C8. The patient's serum contained bactericidal antibody for groups A, B, C, and Y meningococci and specific antibody to group Y capsular polysaccharide. There was two to three times more bactericidal antibody activity in the serum than in a pool of normal sera for the infecting strain. Family studies disclosed a sibling who was HLA identical to the patient but whose serum contained normal amounts of total hemolytic and C8 functional activity.

Adolescent↗
PubMed1983

On the Ratio of Photosynthetic Reaction Centers RC2/RC1 in Chlorella.

Chlorella pyrenoidosa (Emerson strain) was grown under high and under low irradiance. Measurements of the O(2) flash yield and the P700 absorption change gave estimates for the ratio of photoreaction centers RC2/RC1 at 1.2 to 1.5. A background light 1 did not increase flash yield.

Journal Article↗
PubMed1983

The effect of sodium intake on the blood pressure related to age and sex.

Two hundred and one volunteers with no known hypertension and 60 patients with untreated hypertension were entered into a study that compared the effect of two levels of sodium intake on blood pressure. One hundred and fifty-four volunteers and 46 hypertensive patients reached compliance goals, with a urinary sodium excretion on the high sodium diet twice that on the reduced sodium intake. The blood pressure on the high sodium diet was 4.5 +/- 0.5 mmHg (n = 154 p less than 0.001) higher than on the reduced sodium diet in normotensive individuals and was increased by 8.4 +/- 1.5 mmHg (n = 46 p less than 0.001) in hypertensive individuals. In the volunteer group the major rise in blood pressure occurred in people over the age of 50. In the hypertensive patients the alteration in blood pressure was not age dependent. In the younger age groups some individuals had an increase in blood pressure when on the high sodium intake which was outside the spontaneous variations in blood pressure of a control group. This implied that a number of young normotensive individuals were susceptible to this alteration in sodium intake. Changes in sodium intake alter blood pressure in hypertensive people, in normotensive people over 50 and in a small number of younger normotensive people. Overall reduction of sodium intake from 200 - 70 mmol/day would reduce the blood pressure level of the population and would reduce the number of people who have a blood pressure that requires drug therapy.

Adolescent↗
PubMed1982

Protochlorophyll(ide) in a Blue-Green Alga.

During growth under far-red (>650 nm) light, Anacystis nidulans accumulates protochlorophyllide to concentrations about one-tenth of the chlorophyll. From whole cell fluorescence spectra, protochlorophyll(ide) was identified also in another blue-green, and in a red, alga grown in far-red light.

Journal Article↗
PubMed1982

Multidisciplinary treatment of advanced Hodgkin's disease by an alternating chemotherapeutic regimen of MOPP/ABDV and low-dose radiation therapy restricted to originally bulky disease.

Ninety-one evaluable patients with advanced Hodgkin's disease (patients with stages IIB, IIIB, or IV disease and patients with IIIA disease who were greater than 35 years old or had mixed cellularity or lymphocyte depletion histology) received chemotherapy with MOPP and ABDV given in alternating months; radiation therapy (RT) (2000 rad in 2 weeks) was given during Month 5 of therapy to the previously untreated patients through ports that were limited to the originally bulky disease. The complete remission rates observed were: 88% in previously untreated patients, 69% in patients who had had prior RT but minimal chemotherapy, and 50% in patients who had had prior heavy chemotherapy. The actuarial relapse-free survival rates at 4 years, for patients who had complete remission, are: previously untreated, 84%; prior RT, 70%; and prior heavy chemotherapy, 30%. The total actuarial survival rates at 5 years for all 118 patients, evaluable and nonevaluable, who were entered in the study, are: previously untreated, 80%, prior RT, 57%; and prior heavy chemotherapy, 40%.

Adolescent↗