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Biomedical subjects

H C Larsen

Publications and source records attributed to H C Larsen.

At least 19 recordsLinked to original sources
PubMed2006

Influence of air intake on the concentration of free fatty acids and vacuum fluctuations during automatic milking.

The main objective of the study was to determine whether the amount of air intake during quarter milking influences the concentration of free fatty acids (FFA) and vacuum fluctuations at the teat end when milking automatically. Air intake in the teat cup was restricted from the normal inlet of 4.5 to 7 L/min to 1.7 and 0 L/min on 2 farms and experiments were carried out as half-udder studies with 40 cows. Blockage of the air inlet reduced FFA from 1.02 to 0.77 mEq/100 g of fat in one herd and from 1.50 to 1.17 mEq/100 g of fat in the other herd. Milk yield per milking was the most significant factor influencing FFA. Air intake accounted for <20% of the variation in FFA concentration. Characteristics of the cow explained the most variation, which could mainly be assigned to the effects of milk yield, fat percentage, fat globule size, and fat globule size distribution. The interval between milkings was not significant when adjusting for milk yields. Blockage of the air inlet caused vacuum fluctuations at the teat end to increase from 15.4 to 21.5 kPa for one model of an automatic milking system (AMS), but from 12.8 to 53.6 kPa for another model. Measurements made with a flow simulator and water revealed that the AMS model and water flow were the most important factors influencing vacuum fluctuations, and that interactions existed between the diameter of the short milk tube and air intake. Free fatty acids in bulk milk from 5,980 herds averaged 0.75 mEq/L of milk for conventional herds and varied from 0.77 to 0.94 mEq/L of milk for the 5 AMS models on the Danish market. Fault detection in 55 herds pointed out that the most frequent faults in conventional herds were air leakages and intake of too much air in the cluster, whereas AMS herds had problems with the cooling and stirring of milk. Correction of the cooling faults caused FFA to decrease by 0.52 mEq/L in the AMS herds. We concluded that air intake during automatic milking is not the most important factor in reducing FFA, whereas milk yield per milking matters the most. More attention should be paid to the cooling and stirring of milk. Reducing the air intake causes vacuum fluctuations during milking to increase significantly.

Air Movements↗
PubMed2001

Longitudinal follow-up of tinnitus complaints.

OBJECTIVE: To investigate the long-term outcome of patients with tinnitus, the long-term effects of cognitive behavioral therapy, and what properties of tinnitus predict distress at follow-up. DESIGN: A longitudinal follow-up of a consecutive sample of patients with tinnitus initially seen by a clinical psychologist. SETTING: Department of Audiology, University Hospital, Uppsala, Sweden. PARTICIPANTS: A consecutive series of 189 patients with tinnitus treated between January 1988 and March 1995 were sent a postal questionnaire booklet. One hundred forty-six (77 women and 69 men) provided usable responses, in all yielding a 77% response rate. MAIN OUTCOME MEASURES: A questionnaire was derived from a structured interview "Questions About Your Tinnitus." Also included were the Tinnitus Reaction Questionnaire and tinnitus-matching data. RESULTS: Questionnaire data showed that many patients with tinnitus still experienced distress an average of 4.9 years after admission. Tolerance of tinnitus increased over time overall. For patients who had received cognitive behavioral therapy (59%), there was a reduction in tinnitus-related distress. Further, an open-ended question showed that the benefits from treatment outnumbered the deficits. Multiple regression analysis showed that tinnitus maskability at admission was a significant predictor of distress at follow-up. CONCLUSIONS: Severe tinnitus shows some signs of improvement over time, especially when psychological treatment has been given. Tinnitus maskability is an important prognostic factor of future tinnitus annoyance.

Adult↗
PubMed2001

Randomized controlled trial of vestibular rehabilitation combined with cognitive-behavioral therapy for dizziness in older people.

OBJECTIVE: To evaluate the effectiveness of vestibular rehabilitation combined with cognitive behavioral therapy in the treatment of dizziness in older people. STUDY DESIGN AND SETTING: A randomized controlled design was used with patients recruited via an advertisement. Nine patients completed treatment and 10 served as waiting-list controls. The intervention lasted 7 weeks with 5 weekly group sessions and consisted of vestibular exercises. Cognitive behavioral therapy components were added to promote relaxation, reduce anxiety, and avoidance of feared situations and movements. RESULTS: Statistically significant improvements on walking time, 2 dizziness provocative movements, and on the Dizziness Handicap Inventory, but no effects on the Romberg or anxiety and depression. Of the treated patients, 89% reached statistical significant improvement on the total inventory score. CONCLUSION: Cognitive behavioral therapy combined with vestibular rehabilitation decreases dizziness in older people. SIGNIFICANCE: These findings indicate that cognitive behavioral therapy can be combined with vestibular rehabilitation in the treatment of dizziness.

Aged↗
PubMed1999

Performance in functional balance tests during menopausal hormone replacement: a double-blind placebo-controlled study.

BACKGROUND AND PURPOSE: Recent studies have indicated that oestrogens might have an effect on postural control. The purpose of this study was to investigate the short-term effect of hormone replacement therapy (HRT) on postural control in menopausal women and to analyse the correlation between sway velocity measures and results of functional balance tests. SUBJECTS: 100 menopausal women who were randomized to receive either HRT or placebo for three months were included in the study. METHOD: The balance function was measured with nine different static and dynamic functional balance tests. The sway velocities were measured on a computerized force platform. RESULTS: No significant differences were found between the two groups in the results of the functional balance tests after the three-month placebo-controlled period or in the changes over time. However, some significant improvements occurred within both groups over this three-month period. The correlations between different sway velocities and the results of the functional balance tests were all very low (r < 0.35). CONCLUSION: It can not be concluded that HRT had a positive effect on the performance in the functional balance tests, as some improvement occurred in both groups. The low correlations indicate that the sway velocity and functional balance tests measure different aspects of balance function.

Analysis of Variance↗
PubMed1999

Distinguishing levels of tinnitus distress.

Degrees of tinnitus distress were explored in a sample of 216 patients who completed audiological measures and were assessed in a structured interview conducted by a clinical psychologist. The Klockhoff and Lindblom grading system was used and its inter-rater reliability assessed in a subsample showing a high degree of correspondence. Results from the interview are reported in terms of variability of tinnitus, characteristics of problematic situations, distress caused by tinnitus, possibilities to cope, and other influencing factors. Finally, a set of discriminant analyses were conducted on the data set resulting in a final model which included pitch, minimal masking level (MML), tolerance in relation to onset, and avoidance of situations because of tinnitus. This model correctly classified 73% of the subjects into the two levels of distress (grade II and III). There may be a potential role for MML as an outcome variable in tinnitus treatment research.

Adaptation, Psychological↗
PubMed1998

Actual and perceived postural sway during balance specific and non-specific proprioceptive stimulation.

A group of patients with balance complaints (n = 16) was compared with a group of normal subjects (n = 17) by means of posturography, subjective assessments of balance, anxiety and unsteadiness when standing on a force platform with eyes closed. Postural instability was induced by vibratory stimulation of the calf muscles (20, 40, 60, 80 and 100 Hz). As a control condition, the arm (biceps) was stimulated at similar frequencies. In order to control for arousal, blood pressure and heart beat were assessed. Furthermore, questionnaire responses on psychological measures were collected. Results showed clear differences between the groups in terms of imbalance and self-reports. However, the 2 groups displayed similar increases of imbalance during calf stimulation and no increase during arm stimulation. Patients generally rated less increase of unsteadiness when the calf was stimulated than did the controls. No differences in arousal were found between the groups or within conditions. Results are discussed in terms of the proposed desynchrony between symptoms and complaints.

Adult↗
PubMed1997

Better postural balance in elderly women receiving estrogens.

OBJECTIVE: The amount of bone mass and the tendency to fall are main risk factors for hip fractures and both deteriorate with advancing age. The dynamics between estrogen exposure and fracture protection seem too rapid to be explained by an effect on bone mass only. Postural balance function may be another potential mechanism for the fracture-protecting effect of estrogens. STUDY DESIGN: We examined 16 long-term users of 17 beta-estradiol implants (20 mg) (mean age 67.9 years and mean duration of treatment 17.3 years [3.3 to 34 years]) and 16 age-matched (+/-2 years) nonusers (mean age 68.3 years). Postural balance (sway velocity) was measured by static posturography before and after blindfolding and application of vibration stimulus (20 to 100 Hz) to the calf muscles to disturb the proprioception and to induce imbalance. RESULTS: Sway velocities were significantly lower in estrogen users than in nonusers (p = 0.0067) and similar to those in young premenopausal women. The differences were accentuated after provocation by blindfolding and by increasing frequencies of vibration stimulus to the calf muscle. Serum levels of estradiol and estradiol/sex hormone-binding globulin were negatively and follicle-stimulating hormone levels positively associated with sway velocity (p = 0.0194, p = 0.0036, and p = 0.0052, respectively) and independent of age (p = 0.02 to 0.005), supporting causality between estrogen exposure and postural balance. CONCLUSIONS: These data indicate that postural balance function is better preserved in long-term estrogen users than in nonusers. Effects on postural balance function may be one mechanism explaining the rapid increase in distal forearm fractures early after menopause and the rapid dynamics between estrogen exposure and hip fracture protection and may potentially reduce the fracture risk in elderly women starting estrogen replacement therapy in spite of marginal increases in bone mass.

Adult↗
PubMed1997

The influence of vertigo, hearing impairment and tinnitus on the daily life of Menière patients.

The aim of this questionnaire study was to investigate the impact of the symptoms in Meniere's disease on the daily life of patients and to analyse the relationships between the cardinal symptoms and environmental, emotional and activity factors. The study comprised 514 patients, recruited from two different sources. The results showed that vertigo, hearing impairment and tinnitus had a strong negative influence on the daily life of patients. Seventy-five percent of the subjects avoided certain everyday activities or situations because of the disease. However, the correlation between discomfort and reported satisfaction with life was moderate. Most of the subjects experienced premonitory symptoms of the attacks and 80% reported relations between external factors and vertigo attacks.

Adaptation, Psychological↗
PubMed1995

[Chronic pancreatitis and upper gastrointestinal hemorrhage].

A 46 year-old woman with a history of chronic pancreatitis, upper epigastric pain and upper gastrointestinal bleeding of obscure origin is presented. A haemoductal pancreatitis was the source of bleeding due to erosion of the splenic artery with bleeding into a pancreatic pseudocyst communicating with the pancreatic duct. This case was special, because there was no aneurysmal dilatation of the splenic artery. This rare entity must always be considered in the diagnosis of gastrointestinal haemorrhage of obscure origin. The appropriate investigation to confirm the diagnosis is visceral angiography, if necessary followed by CT-scan of the abdomen.

Chronic Disease↗
PubMed1994

The cochlear blood flow: a comparison between the laser Doppler and the microsphere surface methods.

Since the introduction in the early 1980s, of the laser Doppler (LD) method for measuring cochlear blood flow (CBF) it has been debated whether the measured changes reflect the total or regional blood flow and whether the method per se influences the CBF. In order to answer those questions, the effect of one vasodilating drug, sodium nitroprusside, was investigated after topical application on the round window membrane (RWM) with respect to its influence on CBF. Two different techniques, the microspheres surface method and the LD method, were used. Untreated animals and animals which received saline or nicotine acid on the RWM were used as controls. The effects on CBF and blood pressure (BP) were continuously registered with LD. When a maximal flow had stabilized, 6 x 10(6) microspheres were injected into the left side of the heart. After the microspheres had been distributed within the body, the animals were killed. Both cochleae were microdissected and the microspheres counted turn by turn in the lateral wall. The number of spheres in the two ears was compared and the difference was recorded as the increase caused by the drug. The percentage change in CBF measured using the LD was compared with that obtained by using the microsphere surface method (MSM). No change in CBF measured by the two techniques was registered in the untreated animals, or after saline or nicotinic acid, while sodium nitroprusside induced a substantial increase in CBF. The mean percentage change of CBF measured with the LD method was compared with the calculated mean percentage change of microspheres for all turns in the cochlea, and in the first turn. Student's t-test and the linear correlation coefficient were calculated.(ABSTRACT TRUNCATED AT 250 WORDS)

Administration, Topical↗
PubMed1994

An experimental evaluation of the effects of transcutaneous nerve stimulation (TNS) and applied relaxation (AR) on hearing ability, tinnitus and dizziness in patients with Menière's disease.

In 20 patients diagnosed with Menière's disease, transcutaneous nerve stimulation (TNS) and applied relaxation (AR) were used as a treatment aimed at reducing tinnitus and dizziness and increasing hearing ability. The main aim of the study was to examine whether TNS could be regarded as a more beneficial treatment regimen than AR. An experimental between-group cross-over design was used. The results from the experimental phase (group comparisons) showed a significantly increased ability to hear for the TNS group when measured on visual analogue scales. During the same period, the AR-group showed a significant hearing improvement for the ear not primarily affected by Menière's disease as measured with pure tone audiometry. The vestibular tests did not reveal any significant changes either after TNS or AR intervention. Tinnitus matching showed changes of pitch and loudness before and after both TNS and AR intervention. However, no statistically significant changes between treatment regimes were found on these measures. The results from this study did not show TNS to be superior to AR in reducing tinnitus, dizziness or increasing hearing ability.

Adult↗
PubMed1993

Konzo: a distinct disease entity with selective upper motor neuron damage.

Two Tanzanian patients with konzo were severely disabled by a non-progressive spastic paraparesis, since the sudden onset during an epidemic six years earlier. At the time of onset they had a high dietary intake of cyanide from exclusive consumption of insufficiently processed bitter cassava roots. MRI of brain and spinal cord were normal but motor evoked potentials on magnetic brain stimulation were absent, even in the only slightly affected upper limbs. Other neurophysiological investigations were largely normal but the more affected patient had central visual field defects. Konzo is a distinct disease entity with selective type upper motor neuron damage.

Adult↗
PubMed1992

Reference values for bicycle exercise tests in patients with various degrees of ischaemic heart disease.

This investigation was carried out in an effort to analyze the influence of various degrees of ischaemic heart disease (IHD) on cardiovascular and physical performance. Assessment of the severity of IHD was based on observations obtained routinely during exercise tests (ST segment response and systolic blood pressure response). The study group included 926 subjects with known or suspected IHD, who were referred for an exercise testing; 268 females, mean age 54 years (range 19-89 years), and 658 males, mean age 52 years (range 16-88 years). We found that increasing IHD severity was associated with significant reductions of cardiovascular performance. The mean maximum work-load (MWL) was lower in females than in males, and MWL as well as mean maximum heart rate (MHR) and mean maximum change in systolic blood pressure (M delta SBP) decreased with increasing IHD and age. The present results may be used to assess the cardiovascular response to exercise in patients with IHD so that altered responses due to causes other than IHD may be identified. Furthermore the result may prove useful in the adjustment of rate responsive pacemakers (RRP) in patients with IHD.

Adolescent↗
PubMed1991

Low-pressure chamber test in Menière's disease.

Lowering of the ambient pressure has been reported to have a positive effect on the symptoms in Menière's disease. In order to further investigate this hypothesis the symptoms in the long-term span were studied in 54 Menière patients who had undergone low-pressure chamber tests. Lowering of the ambient pressure can induce a temporary but not a permanent hearing improvement in patients with Menière's disease. The results also indicate positive effects on other symptoms in Menière's disease, but this could not be statistically proven.

Atmosphere Exposure Chambers↗
PubMed1988

Cochlear blood flow increases after systemic hemodilution: comparison of simultaneous laser Doppler flowmetry and radioactive microsphere measurements.

Guinea pig cochlear blood flow was measured before and after systemic normovolemic hemodilution with high molecular weight dextran. Absolute determinations of blood flow (in the cochlea, brain, kidney and lung) were accomplished by use of radioactive-labeled (85Sr or 141Ce) microspheres. Relative measurements of the cochlear blood flow changes were made simultaneously by the use of a laser Doppler flowmeter. The flowmeter probe was placed on the first cochlear turn. Hemodilution to an average systemic hematocrit of 20% increased cochlear blood flow by 250% as measured with microspheres. The laser Doppler instrument significantly underestimated the actual flow increase giving an indication of 148%. Furthermore, the data, when analyzed on an individual trial basis, showed a very poor correlation between the two methods. The theoretical basis for these findings in relation to the use of the laser Doppler instrument is discussed.

Animals↗
PubMed1988

The microsphere method for studies of inner ear blood flow.

The microsphere method was adapted in 1974 for studies of cochlear blood flow. Since then it has been used in Uppsala, Sweden, at the Department of Otolaryngology, University Hospital, for investigations of the blood flow circulation in the inner ear. The experience with the technique, the subjects, the actual projects and the results are presented and discussed.

Animals↗