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Biomedical subjects

I Wahlberg

Publications and source records attributed to I Wahlberg.

At least 19 recordsLinked to original sources
PubMed2000

Potential nitrite scavengers as inhibitors of the formation of N-nitrosamines in solution and tobacco matrix systems.

The ability of 20 compounds, all but one tobacco constituents, to inhibit the formation of tobacco-specific N-nitrosamines (TSNA) was investigated in buffer and detergent solution and in tobacco midrib and lamina systems. In solution at pH 5.5, ascorbic acid and the phenolic acids caffeic and ferulic acid were the most potent inhibitors of the reaction between nornicotine and nitrite, with nearly complete inhibition at molar ratios test compound/nitrite > 1:1. Also, cysteine > dihydrocaffeic acid > protocatechuic acid approximately catechin acted as strong inhibitors with >90% inhibition at a ratio of 3:1. Lower inhibitions were observed with chlorogenic acid > p-coumaric acid > sclareol > serine. Rutin showed an inhibition of 34% at a ratio of 0.1:1. Sclareol, alanine, proline, and serine did not significantly affect the N-nitrosonornicotine (NNN) formation. alpha-Tocopherol and glutathione enhanced NNN formation at pH 5.5 but were inhibitors at pH 3. Cinnamic acid, vanillic acid, eugenol, and esculin enhanced NNN formation. Increased NNN formation was also observed for dihydrocaffeic acid, chlorogenic acid, protocatechuic acid, and catechin at a less-than-equimolar ratio of test compound to nitrite. The tobacco matrix experiments were performed with air-cured, ground tobacco midrib and lamina. Caffeic acid, ferulic acid, dihydrocaffeic acid and catechin were potent inhibitors of the formation of TSNA in the midrib as well as in the lamina. Also protocatechuic acid, glutathione, ascorbic acid, p-coumaric acid, chlorogenic acid and cysteine were inhibitors, while alpha-tocopherol and rutin inhibited the reaction in the midrib but not in the lamina. Cinnamic acid, vanillic acid, eugenol, alanine, proline and serine showed small effects only. The molar ratio of secondary alkaloid(s)/nitrite in the test systems were 0.1:1 (solution), approximately 0.25:1 (midrib), and approximately 1:1 (lamina) and is most likely the major contributor to the observed order of inhibition potency (solution > midrib > lamina) of the test compounds. The vicinal phenolic hydroxyl groups of polyphenols and the simultaneous presence of a phenol group and an olefinic bond in hydroxycinnamic acids were the most characteristic structural elements of the potent inhibitors.

Free Radical Scavengers↗
PubMed1993

Structure-related inhibiting activity of some tobacco cembranoids on the prostaglandin synthesis in vitro.

Structure-related inhibitory effects on the prostaglandin synthesis in vitro have been detected among eight diterpenoids of the cembrane class (1-8). The 4,6-diols 1 and 2 are the most active of the cembranoids studied with IC50 values of 0.36 and 0.39 mM, respectively, as compared with an IC50 value of 1.4 for acetylsalicylic acid. Lower activities are found for cembranoids having undergone oxidation of/at the 11,12 double bond (5-8), while the 4-hydroxy-6-oxocembranoids 3 and 4 exhibit effects lower than those of 1 and 2 but higher than those of 5-8.

Animals↗
PubMed1992

Tobacco chemistry. 73. 4,6,8-trihydroxy-11-capnosene-2,10-dione, a new cembrane-derived bicyclic diterpenoid from tobacco.

A new diterpenoid containing a rare carbobicyclic cembrane-derived skeleton, the capnosane skeleton, has been isolated from flowers of Greek tobacco. It has been identified as (1S*,3R*,4S*,6R*,7R*,8R*,11Z)-4,6,8-trihydroxy-11-capnosene- 2,10-dione by spectral methods and X-ray analysis of the corresponding benzoate. A full account of the X-ray work is given.

Diterpenes↗
PubMed1986

Tobacco chemistry. 65. Two new 7,8-epoxycembranoids from tobacco.

Two new diterpenoids have been isolated from tobacco. They have been identified as the (1S,2E,4S,6R,7R,8R,11E)- and (1S,2E,4S,6R,7S,8S,11E)-7,8-epoxy-2,11-cembradiene-4,6-diols 1 and 2 by synthesis and X-ray analysis. The conformation about the 5,6 bond in some 7,8-epoxycembranoids is discussed, as is the biogenesis of the two new compounds.

Chemical Phenomena↗
PubMed1985

Gaucher disease--Norrbottnian type. Ocular abnormalities.

Ocular abnormalities in 22 patients with the Norrbottnian type of Gaucher disease are reported. During their first 10 years of life 10 patients had a horizontal gaze abnormality simulating congenital ocular motor apraxia. Examination showed signs of supranuclear oculomotor disturbances in several of them. Thirteen patients had squint secondary to weakness of the abductor muscles; 8/21 examined patients exhibited white retinal infiltrates, which mostly appeared after splenectomy; 8/19 examined patients had myopia. Except for the retinal changes, no connection was found between the abnormalities and the severity of the disease.

Adolescent↗
PubMed1978

Influence of output capacitor, electrode and pulse width on power consumption in cardiac pacing.

Three different types of unipolar endocardial electrodes--47 in all--were compared in regard to power consumption at stimulation threshold with six different output capacitors and seven pulse widths. Fifteen were conventional large surface electrodes (area 47 mm2); 18 were conventional small surface electrodes (area 6 mm2), and 14 had a specially designed tip with a large area but small active surface of 8 mm2. Pulse widths ranged from 0.15 to 2.0 msec and output capacitors from 1.0 to 22.0 microFarads. All in all about 2,000 measurements were performed. The average current drain to the pacemaker output stage was measured and power consumption was calculated for each electrode--pulse width--output capacitor combination. In all combinations, the two small surface electrodes consumed approximately the same amount of power and, in both cases, significantly less than the larger one. With regard to power economy at stimulation threshold, the pulse width of choice was about 0.5 msec and, furthermore, power consumption decreased with increasing capacitor size. The optimal combination was a small surface electrode, an output capacitor of 22 microF and a pulse width of 0.5 msec.

Adult↗
PubMed1977

Low threshold endocaridal electrodes for permanent cardiac pacing. Comparison between one large and two small surface electrodes.

Three different electrodes, i.e. conventional large and small surface endocardial electrodes and a new large contact area-small active surface electrode, have been compared with respect to their stimulation thresholds for cardiac pacing in 94 patients with 96 electrodes. Both capacitor discharge and constant current pulses were used for the measurements. The average 2 msec impulse threshold for the 47 mm(2) electrode reached its maximum on the 14th postoperative day and was 3.6+/-1.4 V and 4.4+/-1.8 mA. One month after insertion, the threshold was 3.2+/-1.4 V and 3.9+/-1.7 mA. Corresponding values after one month for the 6 mm(2) electrode were 2.0+/-1.0 V and 1.7+/-0.9 mA and for the new electrode 1.7+/-0.9 V and 1.4+/-0.8 mA. Thresholds increased by about 20% when the impulse duration was diminished from 2 to 0.5 msec. The new large area-small active surface electrode offers advantages of significantly smaller increases in stimulation thresholds during the first month after insertion and good attachment to the endocardium.

Adult↗
PubMed1976

Single right-sided precordial lead in the diagnosis of right ventricular involvement in inferior myocardial infarction.

The ST segment in a single right-sided chest lead, CR4R, has been studied in 92 consecutive patients with acute inferior transmural left ventricular myocardial infarction. A transient ST- segment rise of more than 1 mm. was recorded in 35 patients, and strongly indicated a significant extension of the infarction to the posterior free right ventricular wall according to autopsy findings. This ECG pattern was furthermore associated with right-sided heart failure, hypotension and oliguria. Left heart failure was also common. The short-term prognosis of patients with ST-segment elevation in CR4R was poor.

Aged↗
PubMed1976

A low-threshold, non-dislocating endocardial electrode.

Threshold curves with large and small surface intracardiac pacemaker electrodes are compared. The 2 msec. impulse threshold with a 47 sq. mm. electrode was 3.6 v. (4.3 mA.) on the fourteenth postoperative day, when it reached its maximum, and 2.8 v. (3.1 mA.) one month after the operation. These values were 45 and 30 per cent lower with a 6 sq. mm. electrode. Thresholds increased by about 20 per cent when the impulse duration was shortened from 2 to 0.5 msec. The small surface electrode consumed about 35 per cent less current than the 47 sq. mm. one. A newly designed large area-small surface electrode with the shape of an open cage, seems to have the advantages of less increase in postoperative thresholds and good attachment to the endocardial wall.

Arrhythmias, Cardiac↗
PubMed1975

Female work capacity during the menstrual cycle: physiological and psychological reactions.

Changes in physical and mental work capacity during the menstrual cycle were studied in 12 healthy woemen with severe menstrual distress. Physiological and psychological tests were performed before, during, and after menstruation. Heart rate, pulmonary ventilation, oxygen uptake, blood lactate concentration, and perceived exertion were measured during work on a bicycle ergometer ar two submaximal work loads corresponding to 40 and 70 %, respectively, of individual maximal oxygen uptake. Mental work capacity was studied with the aid of performance tests of psychological functions such as attention, short-term memory, perceptual speed, perception of time, and reaction time. No change in heart rate or oxygen uptake could be observed over the three phases of the menstrual cycle. However, pulmonary ventilation during work varied significantly. It was highest in the menstrual phase. At the same heart rate exercise on the bicycle ergometer was perceived as more exerting in the menstrual phase than in either the premenstrual or postmenstrual phase. Among the performance tests significant results were obtained only in a test of reaction time, which was slightly impaired during the menstrual phase. The results of the performance tests do not however support the assumption that menstruation affects a woman's mental work capacity.

Adult↗