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Biomedical subjects

A Wennberg

Publications and source records attributed to A Wennberg.

At least 55 records · Page 3Linked to original sources
PubMed1986

Impaired odor perception in tank cleaners.

The olfactory perception of 20 men (tank cleaners) exposed to petroleum products (while cleaning oil tanks) was examined. Office workers and watchmen were used as referents (N = 20 + 20). They were matched with regard to sex, age, and smoking habits. Odor detection thresholds and the perceived odor intensity of four odorous stimuli, pyridine, dimethyl disulfide (DMDS), n-butanol, and heating oil vapor (gas phase of heating oil heated to +40 degrees C), were determined. The results suggested that the tank cleaners had higher absolute odor thresholds for n-butanol and oil vapor than the referents. The psychophysical function of the tank cleaners and referents differed for all the tested substances in respect to odor intensity. The tank cleaners displayed an odor deficit analogous to the hearing loss known as "loudness recruitment," ie, normal perception of strong stimuli but impaired perception of weak stimuli. This odor deficit was therefore named "odor intensity recruitment" and seems, in tank cleaners, to be associated with occupational exposure to oil vapor.

Adult↗
PubMed1986

Instrumentation of the curved root canal using filing or reaming technique--a clinical study of technical complications.

The technical results of two different techniques for instrumentation of root canals were evaluated. The study comprised 520 roots with various degree of curvature treated by supervised dental students using either a reaming of a filing technique. The results indicated that treatment complications were mainly associated with severely curved (greater than or equal to 35 degrees) canals (15-20% of the molars). Instrument breakage and lateral deviation from original canal curvature were more frequent with the reaming technique whereas overfilling and root perforation dominated with the filing technique. Loss in working length occurred with both techniques. It is suggested that the frequency of complications during instrumentation of curved canals might be diminished if files are used for the enlargement of the canal and reamers are used for the final shaping of the apical part.

Adult↗
PubMed1985

Cytotoxicity of corroded and non-corroded dental silver amalgams.

The cytotoxicity of one conventional and four non-gamma 2-amalgams was studied in a cell culture system, using the Millipore filter method. Before testing set amalgam specimens were kept in distilled water or in artificial saliva at pH 4, 5, or 7 for up to 28 wk to produce a corrosion layer on the test surface. Non-corroded set amalgam specimens was also tested. None of the noncorroded, set amalgams showed any sign of surface accumulation of cytotoxic products whereas the corroded amalgams showed varying degrees of cytotoxicity. Generally, the non-gamma 2-amalgams gave a more pronounced cytotoxic effect than the conventional amalgam. When the corrosion procedure was carried out at pH 7, the various non-gamma 2-amalgams showed different degrees of cytotoxicity. It appears that the difference in cytotoxic effect between the non-gamma 2-amalgams and the conventional amalgam as well as the differences among the various non-gamma 2-amalgams could be related to variation in the retention of corrosion products deposited on the amalgam surface.

Animals↗
PubMed1984

Serum lipids and fatty acids composition of tissues in rats on total parenteral nutrition (TPN).

The modulating effect of energy and exogenous triglyceride supply on serum lipids and fatty acid composition of liver, tibialis anterior muscle, subcutaneous and peri-epididymal fat was assessed in rats using Total Parenteral Nutrition (TPN). Nutrients were infused continuously for 10 days through a central vein catheter. Four levels of fat were tested: No fat, Low fat (6% non-protein calories), Medium fat (30%) and High fat (60%), at 2 energy levels (270 kcal and 350 kcal/kg X day). An isonitrogenous supply was given to all groups as 0.9 g N/kg X day. At the highest level of fat intake (20.4 g/kg) at the high energy level triglycerides, cholesterol and phospholipids of serum were elevated. Biochemical signs of essential fatty acid (EFA) deficiency were observed as rising levels of eicosatrienoic acid and lowered concentrations of linoleic and arachidonic acid, mostly in the liver and the muscle in the No fat groups. EFA levels were reduced significantly in the No fat and Low fat groups and more pronounced at the high energy level. In conclusion, our study suggests that when energy intake is increased the EFA status becomes more critical. It seems evident that more EFA is required in absolute values when hypercaloric diets are given.

Adipose Tissue↗
PubMed1984

Prognosis of alcoholic peripheral neuropathy.

Ten male alcoholics aged 38-72 years with clear clinical and electroneurographical signs of peripheral neuropathy were re-examined three to five years later. Conduction velocities, latencies and nerve action potential amplitudes were measured from median, peroneal and sural nerves on both occasions and the results were compared with age-matched reference values from 80 healthy men. Seven of the alcoholics showed normal or nearly normal scores in electroneurographical and clinical examination and they had all managed to stop drinking alcohol. The results suggest that the prognosis of alcoholic peripheral neuropathy is good and independent of age provided that intake of alcohol is discontinued and other causes of neuropathy (malignancy, diabetes, nerve trauma) are carefully excluded.

Adult↗
PubMed1984

A neuropathy index based on motor-sensory electroneurography (ENeG).

Measuring motor and sensory nerve conduction velocity and amplitude of sensory nerve action potentials (ENeG) is an adequate and sensitive way to detect diffuse polyneuropathies. However, due to inter-individual variations, the normal range of each ENeG parameter is quite wide and thus in mild cases of neuropathy all ENeG parameters might be below normal mean values but still within the normal range. A polyneuropathy index based upon ten different ENeG parameters is proposed. It is shown to be sensitive enough to demonstrate neuropathy in single cases and useful when following the course of a neuropathy.

Adolescent↗
PubMed1983

Biological evaluation of dental restorative materials--a comparison of different test methods.

Three restorative materials--two composite resins and zinc oxide-eugenol cement--were subjected to three cytotoxicity tests--chromium release, millipore filter, and agar overlay--one implantation test, and a pulp study. In the cytotoxicity test the materials were evaluated freshly prepared and after storage at 37 degrees C for 24 h. In the implant test polyethylene tubes holding freshly prepared materials were inserted subcutaneously into rats. After 30 and 90 days the tissue response at the end of the tube and at a window site along the side of the tube was assessed. In the pulp study the materials were placed in cavities prepared in newly erupted monkey teeth. After 7 and 78 days the reaction of the pulp tissue was studied. Comparison of the results from the cytotoxicity tests revealed a varying degree of correlation, indicating that the three tests were not interchangeable. When data from the pulp study were compared to those of the cytotoxicity tests and implantation test, the correlation was not as good. This emphasizes that the final biological evaluation of dental restorative materials still has to be carried out as pulp studies.

Animals↗
PubMed1983

Psychiatric and neurological symptoms in workers occupationally exposed to organic solvents--results of a differential epidemiological study.

It is accepted knowledge today that repeated intoxication with organic solvents damages the central nervous system and causes persistent psycho-organic symptoms. That long-term but low-level occupational exposure--typical o painters and other blue-collar workers--can also induce such disorders has not generally been recognized. The present epidemiological study was undertaken to evaluate the possible neuropsychiatric effects of such exposure. 80 laquerers exposed to a mixture of industrial solvents (average hygienic effect 0.3) and 37 printers exposed almost only to toluene (average hygienic effect 1.0) were compared with a control group of 80 age-matched non-exposed subjects. In psychiatric interviews, the painters showed more mental symptoms. Fatigue, nervousness and lack of manual dexterity were most important and formed a typical neurasthenic syndrome. A general decrease in conduction velocity and action potential amplitude was also observed for the peripheral nerves. The printers showed a large decrease of the nerve action potential amplitude only for the sural nerve. No EEG abnormalities were found. Nor could any increase in mental symptoms be detected through psychiatric interviews compared to the controls. The results are interpreted as evidence for a CNS affection with consequent neuropsychiatric signs and symptoms after long-term occupational exposure to mixtures of industrial solvents below the current threshold limit values (TLV) but not after exposure to a single substance like toluene at about the TLV. The differential effects may be explained by synergistic amplification of the toxicity of solvent mixtures.

Adult↗
PubMed1983

Small intestinal dipeptidases and disaccharidases in uraemic rats on a low protein diet.

Small intestinal dipeptidases (substrate: glycyl-L-leucine, L-methionyl-L-methionine, and L-alanyl-L-proline) were determined in uraemic and sham-operated rats given normal protein diet (24%), low protein diet (6%), and total parenteral nutrition for 10-14 days. Disaccharidases (substrate: maltose, sucrose, trehalose, and lactose) were measured after normal and low protein diet orally. Glycyl-L-leucine and L-methionyl-L-methionine splitting activities were increased on normal protein diet but decreased after low protein feeding in uraemic rats. Parenteral nutrition further lowered the enzyme activity. L-Alanyl-L-proline dipeptidase activity showed an inverse relation to protein intake with the highest values after parenteral nutrition. Lactase increased in uraemic rats after low protein feeding and was the only disaccharidase to be affected by the nutritional change. It is suggested that the changes of the intestinal dipeptidase activities in uraemia are adaptive to variation in the luminal content of di- and oligopeptides because of the type of nutrition given.

Animals↗
PubMed1982

Rate of formation of regular and irregular secondary dentin in monkey teeth.

An in vivo hard-tissue labeling technique was used to study the formation of regular and irregular secondary dentin in thirty-one monkey teeth. The formation of regular secondary dentin averaged 0.8 micrometer per day. No difference was found in the rate of formation of regular secondary dentin and irregular secondary dentin associated with attrition. The formation of irregular secondary dentin following restorative procedures averaged 2.9 micrometers per day. During the first 30 postoperative days less irregular secondary dentin was formed subjacent to deep cavities as compared to shallow ones. This could be the result of an initial injury to the odontoblasts caused by the operative and/or restorative procedures.

Animals↗
PubMed1982

Plasma free amino acid levels in uremic rats given high and low protein diets or intravenous infusions of amino acid solutions.

Plasma free amino acids were measured in uremic and sham-operated rats fed for 10 days a high (24%) or a low (6%) protein diet or given total parenteral nutrition, either with a complete amino acid solution or a solution containing only the amino acids considered to be indispensible in uremia. The plasma levels of citrulline, glycine, hydroxyproline, and 1- and 3-methylhistidine were elevated in all uremic rats compared with the corresponding controls. Plasma tryptophan was reduced in three out of four uremic groups and the brached-chain amino acids and tyrosine were reduced in plasma of orally fed uremic rats but not after intravenous infusion. Plasma serine increased with increased plasma glycine levels. The ratio serine:glycine was, however, significantly smaller in the uremic rats. The ratios of plasma valtine:glycine and indispensable:dispensable amino acids were affected by nitrogen intake as well as by uremia, whereas plasma citrulline:tryptophan was influenced only by the uremic state. This ratio was markedly elevated in all uremic groups. The alterations observed in the plasma free amino acid levels and ratios of the uremic rats were similar to those reported from clinical observations on patients with chronic renal failure.

Amino Acids↗
PubMed1982

Effects of total parenteral nutrition in rats with experimental chronic renal failure.

The effects of total parenteral nutrition (TPN) in partially nephrectomized rats (n = 17) and sham-operated controls (n = 12) were evaluated and compared to the effect of low and high nitrogen oral diets (6% and 24% protein). TPN included fat (9 g/kg per day), high energy (1385 KJ/kg per day), and low nitrogen content (0.6 g N/kg per day, corresponding to 8% protein) either as essential amino acids (EAA) or as a mixture of essential and nonessential amino acids (CAA). The parenteral nutrition was administered intravenously via a permanent catheter continuously for 10 days. Most animals tolerated the treatment with no signs of overhydration or electrolyte imbalances. Uremic rats on TPN gained in weight similarly to control animals, whereas uremic rats given oral diets showed a lower weight increase. Both amino acid solutions promoted positive nitrogen balance and growth. Plasma urea dropped during TPN and low protein oral feeding in uremic and control rats, but not in the high protein-fed animals. Serum creatinine decreased with TPN but not with oral feeding in uremic rats. Albumin and hemoglobin levels were significantly reduced in all uremic rats irrespective of dietary treatment. The experimental model presented here could be useful for further studies on parenteral nutrition in uremia.

Amino Acids↗