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Biomedical subjects

O Johnson

Publications and source records attributed to O Johnson.

At least 55 records · Page 3Linked to original sources
PubMed1991

Is HLA B27 antigen a predictor of cardiac or pulmonary disease in patients with rheumatoid arthritis?

Pericarditis was a frequent echocardiographic finding in 20 HLA B27 positive patients with erosive, seropositive rheumatoid arthritis (RA) and in 20 B27 negative RA controls (35% and 30% respectively). There was no significant difference in echocardiographic 2-D or M-mode measurements between the groups. A 48 hour continuous electrocardiographic monitoring, showed that ventricular extrasystoles were more frequent (p less than 0.01) in the B27 negative patients. Pulmonary diffusion capacity was reduced in 25% of the patients in both groups. There were no association between clinical or laboratory data and the cardiac or pulmonary findings except for the finding of a higher frequency of treatment with corticosteroids in patients with pericarditis.

Arthritis, Rheumatoid↗
PubMed1991

Chronic idiopathic thrombocytopenic purpura (ITP) in adult Ethiopians: clinical findings and response to therapy.

Between January 1982 and December 1989, thirty four cases of chronic idiopathic thrombocytopenic purpura (ITP) were seen in adult Ethiopians in the Department of Internal Medicine in-patient and haematology referral clinic, of Tikur Anbessa teaching hospital. Twenty three were females and eleven males; female to male ratio of 2.1:1. The age range was 13-57 years, with a mean of 24.9 years. The commonest manifestations were: purpura, epistaxis, gum-bleeding and menorrhagia. The duration of symptoms ranged from one month to over ten years (median 4.5 months). The platelet counts ranged from 4000/mm3 to 77,000/mm3 (mean - 19,200/mm3), haemoglobin 3.01 to 15.4 gm/dl (mean - 8.2 gm/dl). Four (11.8%) patients were not treated; of these, one went into spontaneous remission. Thirty patients (88.2%) were treated with prednisolone 1.0 to 1.5 mg/kg/day orally. Of these, 7 (23.3%) had excellent, 2 (6.7%) good, 6 (20%) fair, and 15 (50%) had poor responses. Ten patients had splenectomy with 5 (50%) excellent 2 (20%) good, 2 (20%) fair and 1 (10%) poor response. One patient with refractory ITP was treated with immunosuppressive drugs and had an excellent response. Fifteen patients are alive and on followup 3-122 months (median 33 months) after diagnosis, fifteen are lost after followup of 1-66 months (median 9 months) and four have died 1-18 months (median 2 months) after diagnosis. Chronic ITP is frequently seen in adult Ethiopians, its clinical features and response to therapy are similar to those reported in the literature.

Adolescent↗
PubMed1989

A comparison of the crystal structures of some quaternary trimethylammonium salts related to dopamine and noradrenaline with those of the corresponding amines: a comment on their nicotine-like biological activities.

The crystal structures of seven substituted phenethylammonium salts and one (phenylpropyl)-ammonium salt have been determined. (I) Trimethyl(phenethyl)ammonium iodide, C11H18N+.I-, Mr = 291.2, orthorhombic, P2(1)2(1)2(1) (No. 19), a = 6.040 (2), b = 7.689 (2), c = 26.528 (9) A, V = 1232 (1) A3, Z = 4, Dx = 1.56 g cm-3, Mo K alpha radiation (lambda = 0.71073 A), mu = 25.33 cm-1, F(000) = 576, T = 298 K, R (wR) = 0.0302 (0.0305) for 1991 reflections with I greater than 3 sigma (I). (II) (p-Hydroxyphenethyl)trimethylammonium iodide, C11H18NO+.I-, Mr = 307.2, triclinic, P1 (No. 2), a = 9.619 (1), b = 9.926 (1), c = 14.179 (2) A, alpha = 95.24 (1), beta = 97.50 (1), gamma = 98.97 (1) degrees, V = 1317.2 (3) A3, Z = 4, Dx = 1.55 g cm-3, Mo K alpha radiation (lambda = 0.71073 A), mu = 23.79 cm-1, F(000) = 608, T = 298 K, R (wR) = 0.0351 (0.0373) for 4320 reflections with I greater than 3 sigma (I). (III) (m-Hydroxyphenethyl)trimethylammonium iodide hemihydrate, C11H18NO+.I-.1/2H2O, Mr = 316.2, monoclinic, P2(1)/n (non-standard, No. 14), a = 8.048 (2), b = 9.782 (3), c = 17.447 (7) A, beta = 90.15 (1) degrees, V = 1374 (2) A3, Z = 4, Dx = 1.53 g cm-3, Mo K alpha radiation (lambda = 0.71073 A), mu = 22.86 cm-1, F(000) = 628, T = 298 K, R (wR) = 0.0719 (0.0655) for 1006 reflections with I greater than 1 sigma (I).(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1989

The X-ray crystal structure of 4-diphenylcarbamyl-N-methyl-piperidine methobromide (the carbamate analogue of 4-DAMP methiodide).

1. Crystals of 4-diphenylcarbamyl-N-methylpiperidine methobromide contain 2 conformers, one with the ester group equatorial and the other with the ester group axial to the piperidine ring. 2. In both conformers and diphenylcarbamyl nitrogen is trigonally substituted and flat compared with the tetrahedral substitution of the corresponding carbon atom in 4-diphenylacetoxy-N-methylpiperidine (4-DAMP) methiodide. 3. The low activity and selectivity of the carbamate at muscarinic receptors is comparable with that of compounds containing only one phenyl ring, e.g. phenylacetyl-N-methyl piperidine methiodide or phenylacetylcholine. It is suggested that the high affinity of 4-DAMP metho-salts and their selectivity depend upon interactions with groups arranged in three dimensions and that the trigonal arrangement about the nitrogen atom in the carbamate makes it impossible for both benzene rings to interact at once.

Crystallization↗
PubMed1989

Relations between structure and nicotine-like activity: X-ray crystal structure analysis of (-)-cytisine and (-)-lobeline hydrochloride and a comparison with (-)-nicotine and other nicotine-like compounds.

1. Although (-)-cytisine is a rigid structure, it occurs in the crystal in two distinct but very similar conformations in which the pyridone ring is tilted relative to the charged nitrogen atom at much the same angle as the pyridine ring is in (-)-nicotine hydrogen iodide. The carbonyl group in the pyridone ring of (-)-cytisine, however, is on the side of the ring opposite to pyridine nitrogen in (-)-nicotine. 2. The pKa of (-)-lobeline HCl at 25 degrees C is 8.6 (approx), indicating that (-)-lobeline is at least 90% in the protonated form at physiological pH (7.6). It is probably the phenyl 2-keto-ethyl part of (-)-lobeline, rather than the phenyl 2-hydroxy-ethyl part, which interacts with the receptor. 3. The combination within one molecule of a charged ('onium') nitrogen atom lying out of the plane of, and some distance (4.5-6.5 A) from, an aromatic ring is common to many compounds with nicotine-like activity (e.g. nicotine, cytisine, choline phenyl ether bromide, dimethyl-phenyl-piperazinium (DMPP) iodide, coryneine iodide and m-hydroxyphenylpropyl trimethyl ammonium iodide). In some molecules the aromatic ring can be replaced by an unsaturated group, such as carbonyl (e.g. acetylcholine) or double-bonds (e.g. anatoxin). 4. Activity at nicotinic receptors appears to involve interactions between the positively charged nitrogen atom and a negatively charged group, probably close to cysteine residues 192 and 193 in the receptor. It is suggested that rather than specific groups in the molecule also being involved, activity at nicotinic receptors depends on interactions between a flat part of the drug containing double-bonds, or systems of double bonds, and a planar area in the receptor, possibly tyrosine or phenylalanine residues.

Alkaloids↗
PubMed1989

Haptoglobin groups in acute myocardial infarction.

In patients with acute myocardial infarction, the haptoglobin (HP) groups were found to be associated with serum cholesterol levels. Heterozygotes (HP 2-1) showed serum cholesterol levels significantly higher (p less than 0.0001) than those of patients with HP 1-1 or HP 2-2. Furthermore, an association between HP type and infarction size was observed, HP 2-2 being associated with smaller infarctions.

Aspartate Aminotransferases↗
PubMed1987

The extrinsic fibrinolytic system in survivors of myocardial infarction.

The extrinsic fibrinolytic system was assessed among 124 consecutive survivors of acute myocardial infarction below 70 years of age. In samples drawn 3 months after discharge from hospital, the PAI-1 levels were higher and the tPA activities were lower than among elderly healthy controls. In contrast, the AMI survivors had higher tPA antigen levels at rest and after venous occlusion, and higher tPA activities after venous occlusion. Among patients having PAI-1 levels greater than 10 IU/ml, there was a positive correlation between PAI-1 and serum triglycerides, and a negative correlation between PAI-1 and age; this group was also significantly younger than the subgroup having less than or equal to 10 IU/ml of PAI-1. There were thus multiple disturbances of the extrinsic fibrinolytic system among these patients. As cardiovascular risk factors, these disturbances appear to be relatively more important the younger the patients are.

Adult↗
PubMed1986

Molecular structure of 1,8-dimethylfluoren-9-one.

The molecular and crystal structure of the synthetic 1,8-dimethyl derivative of 9H-fluoren-9-one (F-9-one) has been determined by direct methods from X-ray diffractometric data and refined to an R index of 0.035 over 1216 independent reflections. With a mutual inclination between benzene rings of 178.6 degrees, the molecule is closely planar; of the non-hydrogen atoms, only the oxygen is as much as 0.08 A out of the plane defined by the ring-joining carbons C(10), C(11), C(12) and C(13). Neither the carbonyl bond nor the beach bond C(11)-C(12) differs significantly from the corresponding bonds in F-9-one and the 2,7-diamino compound; C-C bonds involving methyl carbons and the keto carbon are all very close to 1.50 A long (e.s.d. 0.003 A). The C-C(methyl) bonds are bent so that angles C(10)-C(1)-C(14) and C(13)-C(8)-C(15) are about 123 degrees, while the methyl groups are orientated with one hydrogen from each pointing away from the carbonyl group.

Crystallization↗
PubMed1985

Familial aortic aneurysms: serum concentrations of triglyceride, cholesterol, HDL-cholesterol and (VLDL + LDL)-cholesterol.

Patients with abdominal aortic aneurysms (AAAs) have been compared with healthy controls with respect to the serum concentrations of triglyceride, cholesterol, HDL-cholesterol and (VLDL + LDL)-cholesterol. The concentrations of triglyceride and (VLDL + LDL)-cholesterol in serum were higher in the patients than in the controls, while the concentration of HDL-cholesterol in serum was lower in the patients than in the controls. There was no statistically significant difference in the serum concentration of total cholesterol between the patients and the controls. Twelve patients had first degree relatives (brothers, sisters and/or parents) with AAAs and six patients had second degree relatives (cousins or brothers and sisters of the parents) with AAAs. There was no statistically significant difference between the patients who had first degree relatives with AAAs and the patients without AAAs in the family in the serum concentrations of triglyceride, cholesterol, HDL-cholesterol and (VLDL + LDL)-cholesterol.

Aged↗
PubMed1985

Clearance of triglycerides from the circulation and its relationship to serum lipoproteins: influence of age and sex.

In this study of a randomly selected population from 20 to 70 years of age, the clearance of triglycerides from the blood was studied after i.v. injection of an artificial triglyceride emulsion Intralipid. In women, the triglyceride clearance from the blood decreases with increasing age, but for men there was no change with age. Women had faster fractional removal rates of i.v. injected triglycerides than men in all age-groups. The triglyceride clearance showed a negative correlation to Broca index (obesity), serum triglyceride, serum cholesterol, triglycerides in very low density lipoproteins, and to cholesterol in very low density lipoproteins and in low density lipoproteins, but showed a strong positive correlation to cholesterol in high density lipoproteins.

Adult↗
PubMed1984

Decreased removal of triglycerides from the blood--a mechanism for the hypertriglyceridemia in male patients with coronary artery disease.

We determined serum apolipoprotein A I and A II concentrations and triglyceride and cholesterol concentrations in serum lipoprotein density classes in 28 male patients with severe ischaemic heart disease (IHD) and with angiographically verified coronary artery disease (CAD) and in age-matched controls. Both triglyceride and cholesterol concentrations in very low density lipoproteins and in low density lipoproteins were higher in IHD-patients than in the controls. The triglyceride but not the cholesterol concentration in serum was higher in IHD-patients than in the controls. The cholesterol in high density lipoproteins and the serum apolipoprotein A I concentration were lower in IHD-patients than in the controls. At least in part the higher triglyceride concentration in very low density lipoproteins could be attributed to a decreased removal of triglycerides from the blood since the fractional removal rate of an i.v. injected artificial triglyceride emulsion (Intralipid) was slower in IHD-patients than in the controls.

Adult↗
PubMed1982

Serum lipoproteins and apolipoproteins A I and A II in male patients with peripheral arterial insufficiency.

Serum apolipoprotein A I and A II concentrations and triglyceride and cholesterol concentrations in serum lipoprotein density classes were determined in male patients with peripheral arterial insufficiency (PAI) and in controls. Both triglyceride and cholesterol concentrations in serum, very low and low density lipoproteins were higher in PAI patients than in controls. The cholesterol in high-density lipoproteins and the serum apolipoprotein A I concentration were lower in PAI patients than in controls. No difference between the groups was found for serum apolipoprotein A II concentration. The results show that the lipoprotein pattern in PAI is changed in roughly the same way as in ischemic heart disease.

Adult↗
PubMed1982

Serum lipoproteins, apolipoproteins and intravenous fat tolerance in young athletes.

Serum lipoproteins, apolipoproteins and intravenous fat tolerance were studied in 22 male athletes and compared with healthy age and weight-height matched controls. All of the subjects were non-smokers. Athletes had lower serum, very low density lipoprotein (VLDL) and low density lipoprotein (LDL) triglycerides, lower serum VLDL and LDL cholesterol and an increase in apolipoprotein A I. High density lipoprotein (HDL) cholesterol was similar in both groups. The clearance of i.v. injected triglyceride emulsion was faster in athletes. This suggests that the lower serum and VLDL triglycerides in athletes are at least in part due to a more rapid triglyceride clearance.

Adult↗