Biomedical subjects

B R Jensen

Publications and source records attributed to B R Jensen.

At least 37 records · Page 2Linked to original sources

PubMed1999

Low-protein diet and kidney function in insulin-dependent diabetic patients with diabetic nephropathy.

BACKGROUND: Initiation of a low-protein diet (LPD) in patients with various nephropathies induces a faster initial and slower subsequent decline in the glomerular filtration rate (GFR). Whether this initial phenomenon is reversible or irreversible remains to be elucidated. METHODS: We performed an eight-week prospective, randomized, controlled study comparing the effect of an LPD with a normal-protein diet (NPD) in 29 insulin-dependent diabetic patients with diabetic nephropathy. At baseline, the patients were randomized to either an LPD (0.6 g.kg-1.24 hr-1, LPD group, N = 14) or their NPD (NPD group, N = 15) for four weeks (phase I). Between weeks 4 and 8, all patients received their NPD (phase II, recovery). Dietary protein intake (g.kg-1.24 hr-1), GFR (51Cr-EDTA, ml.min-1.1.73 m-2), albuminuria (enzyme-linked immunoadsorbent assay, mg.24 hr-1), and arterial blood pressure (Hawksley random zero sphygmomanometer, mm Hg) were measured at baseline and after four- and eight-weeks of follow-up. During the investigation, all patients in the LPD group (N = 12) and in the NPD group (N = 14) received their usual antihypertensive treatment. RESULTS: At baseline, the LPD group and the NPD group were comparable regarding dietary protein intake, GFR, albuminuria, and arterial blood pressure. During phase I, a significant decline in dietary protein intake, GFR, and albuminuria (mean, 95% CI) was observed in the LPD group [0.4 (0.3 to 0.5) g.kg-1.24 hr-1, 8.6 (3.2 to 13.9) ml.min-1.1.73 m-2, and 28.7 (14.0 to 40.9)%, respectively] compared with the NPD group [0.0 (-0.1 to 0.2) g.kg-1.24 hr-1 (P < 0.0001 between diets), 2.5 (-1.8 to 6.8) ml.min-1.1.73 m-2 (P = 0.07 between diets), and 0.0 (-20.1 to 23.5)% (P < 0.05 between diets), respectively]. Conversely, during phase II, a significant increase in dietary protein intake, GFR, and albuminuria [mean, 95% CI; 0.3 (0.2 to 0.5) g.kg-1.24 hr-1, 5.9 (0.8 to 11.1) ml.min-1.1.73 m-2, and 25.0 (4.5 to 49.6)%, respectively] took place in the LPD group compared with the NPD group [0.0 (-0.2 to 0.1) g.kg-1.24 hr-1 (P < 0.0001 between diets), -2.9 (-6.4 to 0.6) ml.min-1.1.73 m-2 (P < 0.01 between diets), and 2.9 (-18.3 to 29.7)% (P = 0.16 between diets), respectively]. Arterial blood pressure was comparable in the two groups of patients during phase I and II. CONCLUSIONS: Dietary protein restriction for four weeks induces a reversible decline in GFR and albuminuria in insulin-dependent diabetic patients with diabetic nephropathy, whereas systemic blood pressure remains unchanged.

Adult↗

PubMed1998

Effect of speed and precision demands on human shoulder muscle electromyography during a repetitive task.

Effects of speed and precision on electromyography (EMG) in human shoulder muscles were studied during a hand movement task where five points were marked repeatedly with a pencil. Six female subjects performed with three precision demands and at four speeds. Three of the speeds were predefined, while the last speed was performed as fast as possible. The EMG were recorded from 13 shoulder muscles or parts of muscles. Elbow velocity, acceleration and rectified EMG were calculated for each task. The mean elbow velocity and acceleration increased with speed and precision demands. There was an increase in EMG as the speed demand increased for all three precision demands (P < 0.001), and as the precision demand increased for the two highest predefined speed demands (P < 0.05). The combination of a high speed and a high precision demand resulted in the highest EMG. Different EMG levels were attained for the 13 muscles and the supraspinatus muscle always showed the highest normalized EMG. However, analysis of variance showed the same relative increase for all muscles with speed and precision demands. The EMG changes in response to precision demand can only be explained in part by the differences in movement velocity and acceleration, and other factors such as increased co-contraction must also be taken into account.

Aged↗

PubMed1998

A model predicting individual shoulder muscle forces based on relationship between electromyographic and 3D external forces in static position.

To study the potentiality for developing an EMG-based model for the human shoulder, mapping of relations between static hand forces and electromyographic (EMG) activity of 13 shoulder muscles, were performed. The procedure was to perform by the hands slowly varying isometric forces up to 20% maximum voluntary force in the three-dimensional space. By combining these data with literature values on muscle physiological cross-sectional area and moment arm data, an EMG-based model was developed for estimating muscle forces in the glenohumeral joint. The model was validated for one standardized position by comparing joint moment, calculated from EMG by using the model, with moments from the external force. The highest correlation between these moments was found assuming a linear EMG/force calibration at low force level (< 20% MVC), giving correlations from 0.65 to 0.95 for the abduction/adduction moment and from 0.70 to 0.93 for the flexion/extension moment, for the six subjects. Moments calculated from EMG were for most subjects somewhat lower than the moments from the external force; the mean residual error ranged from 1.6 to 9.9 Nm. Taking this into account, the results can be used for assessment of muscle forces based on recordings of external forces at the hands during submaximal static work tasks without substantially elevated arms.

Adult↗

PubMed1997

Differences between nisoldipine and lisinopril on glomerular filtration rates and albuminuria in hypertensive IDDM patients with diabetic nephropathy during the first year of treatment.

Our objective was to compare the effect of a long-acting calcium antagonist (nisoldipine) versus an ACE inhibitor (lisinopril) on albuminuria, arterial blood pressure, and glomerular filtration rate (GFR) in hypertensive IDDM patients with diabetic nephropathy. We performed a 1-year, double-blind, double-dummy, randomized, controlled study comparing nisoldipine (20-40 mg once daily) with lisinopril (10-20 mg once daily) in 52 hypertensive IDDM subjects with diabetic nephropathy. Three patients dropped out, and results for the remaining 49 (25 nisoldipine, 24 lisinopril) are presented. Diuretics were required in 10 nisoldipine- and 8 lisinopril-treated patients. Every 3 months, 24-h ambulatory blood pressure (TM2420, A&D, Tokyo, Japan) and albuminuria in three 24-h samples (enzyme immunoassay) were measured; GFR (51Cr-EDTA plasma clearance) was recorded every 6 months. Mean arterial blood pressure (24 h) was reduced from (mean +/- SE) 108 +/- 3 mmHg at baseline to 101 +/- 2 in average during treatment in the lisinopril group and from 105 +/- 2 to 103 +/- 2 in the nisoldipine group (P = 0.06 comparing changes in the two groups). Albuminuria was reduced 47% (95% CI 21-65) in the lisinopril group versus an increase of 11% (-3 to 27) in the nisoldipine group (P = 0.001). Fractional albumin clearance was reduced 37% (95% CI 4-59%) in the lisinopril versus an increase of 35% (8-69%) in the nisoldipine group (P < 0.01). GFR decreased from 85 +/- 5 ml x min(-1) x 1.73 m(-2) to 73 +/- 5 in the lisinopril group and from 84 +/- 6 to 80 +/- 7 in the nisoldipine group (P < 0.05). The effect of study medication on albuminuria and GFR was independent of changes in systemic blood pressure and baseline variables in multiple regression analyses. In summary, lisinopril reduced albuminuria, but also GFR, to a greater extent than did nisoldipine in hypertensive IDDM patients with diabetic nephropathy during the 1st year of treatment. Longer follow-up is required to clarify whether these drugs have different renoprotective effects.

Adult↗

PubMed1997

Kidney function after withdrawal of long-term antihypertensive treatment in diabetic nephropathy.

Initiation of antihypertensive treatment in hypertensive non-insulin-dependent diabetic (NIDDM) patients with diabetic nephropathy induces a faster initial (0 to 6 months) and slower subsequent (6 months-end) decline in GFR [delta GFR (ml.min-1.1.73 m-2.month-1) approximately 1.5 vs. 0.4]. Whether this initial phenomenon is reversible (hemodynamic) or irreversible (structural damage) after prolonged antihypertensive treatment is not known. To elucidate these mechanisms we investigated 40 hypertensive NIDDM patients (age 61 +/- 7 years, mean +/- SD), known duration of diabetes 14 years (2 to 33 years) [median (range)] with diabetic nephropathy receiving antihypertensive treatment (angiotensin converting enzyme inhibition, N = 30) for 5 years (1 to 20 years). The following variables were measured the last day on antihypertensive treatment and one month after withdrawal of treatment; GFR (51Cr-EDTA), 24-hour arterial blood pressure (24 hr MABP, Takeda TM2420) and albuminuria (ELISA); the mean 24-hour MABP rose from 102 +/- 11 to 111 +/- 10 (P < 0.0001) and albuminuria [geometric mean (antilog SEM)] increased from 634 (1.3) to 1159 (1.2) (P < 0.0001), while GFR (mean +/- SD) remained unchanged (69 +/- 25 to 70 +/- 26 ml.min-1.1.73 m-2, P = 0.21), after withdrawal of antihypertensive treatment. A significant correlation between the relative change in the 24 hour MABP measurement and the relative change in GFR (r = 0.44, P < 0.01) was found. In conclusion, our results suggest that the faster initial decline in GFR after initiating antihypertensive treatment in hypertensive NIDDM patients with diabetic nephropathy is due to a irreversible effect, and should be accounted for when evaluating the beneficial effect of antihypertensive treatment on the progression of diabetic nephropathy in these patients.

Adolescent↗

PubMed1996

Circadian rhythm of arterial blood pressure and albuminuria in diabetic nephropathy.

The aim of our study was to evaluate the diurnal relationship between arterial blood pressure and albuminuria, and some potential mechanisms responsible for impaired nocturnal blood pressure reduction (non-dippers, groups I and II) in diabetic nephropathy (DN). Twenty-four-hour ambulatory blood pressure, heart rate (HR) variation (autonomic nervous function) and extracellular fluid volume (ECV) were measured, and urine samples were collected three times during the corresponding day- and nighttimes in 47 insulin-dependent diabetic (IDDM) patients with DN. Mean arterial blood pressure (MABP) during the daytime [mm Hg, median (range)] was identical in group I [105 (96-137)], group II [109 (86-124)] and group III [dippers; average blood pressure reduction from day to night > 10%, 107 (93-132), P = NS], while the nighttime MABP differed [group I, 106 (95-144); group II, 100 (78-118); group III, 91 (76-118); P < 0.001]. No significant difference between the groups concerning the daytime or nighttime albuminuria [microgram/min; median (range)] was observed; [Day: group I, 1467 (235-3933); group II, 695 (170-6719); group III, 875 (228-3173). Night: group I, 1079 (279-4665); group II, 572 (113-3807); group III, 659 (81-2493)]. A significant correlation between MABP and albuminuria was demonstrated during day- (rho = 0.50, P < 0.0005) and nighttime (rho = 0.46, P < 0.005), while neither the absolute nor the relative changes in MABP from day to night correlated significantly with absolute or relative changes in albuminuria from day to night. The night/day ratio of HR was higher in group I [0.93 (0.76-1.09), median (range)] compared to group III [0.83 (0.74-1.02), P < 0.005] and a significant correlation between this ratio and the night/day ratio of MABP was found (rho = 0.54, P < 0.0005). ECV was about the same in the three groups. Our study indicated an association between blood pressure and albuminuria, but the mechanisms involved in the reduction of albuminuria from day to night was not unraveled. A relative lack of sympathetic withdrawal during sleep seems to be an important feature of nocturnal hypertension in diabetic nephropathy.

Adult↗

PubMed1996

The acute effect of smoking on systemic haemodynamics, kidney and endothelial functions in insulin-dependent diabetic patients with microalbuminuria.

The acute effect of smoking upon arterial blood pressure, urinary albumin excretion rate, glomerular filtration rate and transcapillary escape rate of albumin were investigated in nine normotensive insulin-dependent diabetic patients with microalbuminuria, who had been smoking for 19 (range 4-30) years. In a prospective, open randomized cross-over design, patients were investigated with and without smoking three cigarettes per hour during a 5.5-h period. A rise in systolic blood pressure and heart rate (Takeda TM2420, median (range)) was observed during the smoking day (10(-11 to 14) mmHg and 8 (-1 to 19) beats min-1), compared to the non-smoking day (1 mmHg (-7 to 13) (p = 0.05) and 0 beats min-1 (-2 to 4) (p < 0.01)). Urinary albumin excretion rate (ELISA), glomerular filtration rate (plasma clearance of 51Cr-EDTA) and transcapillary escape rate of albumin (125I-albumin) remained the same with or without smoking. Our study suggests that heavy smoking induces an abrupt rise in systolic blood pressure and heart rate, while vascular leakage of albumin and glomerular filtration rate remain unaltered in normotensive insulin-dependent diabetic patients with microalbuminuria who had been smoking for several years.

Adult↗

PubMed1996

Motor control and kinetics during low level concentric and eccentric contractions in man.

Motor unit (MU) recruitment patterns were studied in 6 female subjects during dynamic contractions at relative workloads corresponding to 10% maximum voluntary contraction. The contractions consisted of a 20 degree elbow flexion (concentric contraction) and extension (eccentric contraction) and MU action potential trains were recorded from the brachial biceps muscle. The mean angular velocity of the dynamic contractions was 10 degrees/s, during which a total of 119 MUs were identified. Additionally, a few contractions were studied at 20 degrees/s during which 30 MUs were identified, and 9 MUs during the 40 degrees/s contraction. About 60% of the identified MUs were active during the concentric as well as the eccentric phase for each of the velocities. Mean firing rate decreased significantly when the contraction changed from concentric to eccentric, whereas the number and properties of identified active MUs were similar. This emphasizes firing rate modulation as important during low level dynamic contractions rather than selective recruitment of different types of MUs in the concentric versus the eccentric phase. Similar kinetic demands occur frequently in occupational tasks, especially during monotonous work. The present data indicate that only a limited pool of MUs are being recruited during such tasks. Extensive recruitment of these MUs may cause fatigue and start a potentially vicious circle leading to work-related muscle disorders.

Action Potentials↗

PubMed1995

Intramuscular laser-Doppler flowmetry in the supraspinatus muscle during isometric contractions.

To study the regulation of microvascular blood flow in a compartment muscle, laser-Doppler measurements of muscle microcirculation were recorded in the supraspinatus muscle in eight volunteers during and following submaximal isometric muscle contractions. The subjects performed isometric shoulder abductions at five contraction levels from 5% to 50% maximal voluntary contraction for 1 min each and a sustained 30 degrees shoulder abduction for 20 min. The subjects' perceived exertion increased from "no perceived exertion" to "near maximal exertion" during the 20-min period with 30 degrees shoulder abduction. Microcirculation increased during all 1-min contractions. Following the contractions at 20%, 30% and 50% MVC post-exercise reactive hyperaemia was seen for a period of at least 1 min. The reactive hyperaemia increased in magnitude in response to increasing contraction level. The results showed the same time-history of the blood flow at microvascular level as previously seen in larger peripheral vessels in response to muscle contractions. During the 20-min contraction microcirculation increased in line with the findings during the brief contractions. However, in contrast to the brief contractions no postexercise reactive hyperaemia occurred following the prolonged contraction. Lack of postexercise reactive hyperaemia following the prolonged shoulder abduction would suggest insufficient regulation of the vascular resistance. Alternatively, lack of hyperaemia could be taken as an indication of sufficient microcirculation during the preceding contraction. From previous studies on intramuscular pressure and metabolism the latter alternative would seem unlikely.

Adult↗

PubMed1995

Increased glomerular filtration rate after withdrawal of long-term antihypertensive treatment in diabetic nephropathy.

Initiation of antihypertensive treatment (AHT) in hypertensive insulin-dependent diabetic (IDDM) patients with diabetic nephropathy (DN) induces a faster initial (0 to 6 months) and a slower subsequent (6 months to end of observation) decline in GFR [delta GFR (ml/min/month) approximately 1.5 vs. 0.35]. Whether this initial phenomenon is reversible (hemodynamic) or irreversible (structural damage) after prolonged AHT is not known. To elucidate these mechanisms we investigated 42 hypertensive IDDM patients (16F/26M, age 40 +/- 7 years, mean +/- SD) with DN receiving AHT (angiotensin converting enzyme inhibition, N = 30) for 6 (2 to 15) years [median (range)]. GFR (ml/min/1.73 m2), arterial blood pressure (BP, mm Hg) and albuminuria (mg/24 hr) were measured the last day on AHT and one month after withdrawal of AHT. The measured variables were all significantly elevated after withdrawal of AHT: GFR [mean(SEM)] from 76(4) to 81(4) (P < 0.0001), BP [mean(SEM)] from 140/82 (2/1) to 151/89 (2/1) (P < 0.0005) and albuminuria [geometric mean (antilog SEM)] from 704 (1.2) to 1122 (1.2) (P < 0.0001). A correlation between relative rise in systolic blood pressure (delta Sys%) and relative change in GFR (delta GFR%) was found (r = 0.44, P < 0.005). Our results render some support of the hypothesis that the faster initial decline in GFR is due to a functional (hemodynamic) effect of AHT, which does not attenuate over time, while the subsequent slower decline reflects the beneficial effect on progression of diabetic nephropathy.

Adult↗

PubMed1995

Soft tissue architecture and intramuscular pressure in the shoulder region.

Soft tissue architecture including muscle insertions were studied in the shoulder region by dissecting three male cadavers. These dissections demonstrated that m. supraspinatus and mm. infraspinatus/teres minor were located in two separate, closed compartments limited by bony walls and tense stiff fascia. M. supraspinatus was composed of two parts which differed with respect to attachment site, fibre orientation, and muscle structure although they were similar with respect to muscle fibre length. Muscle structure, fascia and insertion sites should be taken into account in biomechanical modeling of the shoulder. Intramuscular pressures in the shoulder muscles were recorded in healthy females during voluntary isometric contractions performed in various arm positions, and at different contraction levels and measuring depths. Intramuscular pressure in m. supraspinatus during 30 degrees shoulder abduction: 58 (33-70) mmHg, exceeded the intramuscular pressure during 30 degrees flexion: 29 (7-40) mmHg. In m. infraspinatus lower values were registered. A simple relation between intramuscular pressure and measuring depth did not exist in the soft tissue above fossa supraspinata. During contractions a steep increase in intramuscular pressure was seen at a depth corresponding to the transition from m. trapezius to m. supraspinatus. The intramuscular pressure measurements showed wide regional heterogeneity at the same measuring depth during contractions, which is likely to be due to the complex anatomy found in this region. The results show the significance of the anatomy for the increase in intramuscular pressure during contractions. This in turn may impair muscle blood flow and thus affect muscle function over prolonged periods of time.

Aged↗

PubMed1994

The effect of prolonged isometric contractions on muscle fluid balance.

Ultrasound scanning was performed at three sites above the fossa supraspinata on nine healthy subjects and five patients with myofascial shoulder pain. This method produced a well-defined depiction of the soft tissue layers above the fossa supraspinata and reproducible muscle thickness measurements. In the healthy subjects the average distance from the skin surface to the trapezius muscle was 7.7 mm and the average thickness of the trapezius muscle was 5.3 mm, and the average thickness of supraspinatus muscle was 20.0 mm. The supraspinatus muscle was thinner at the medial measuring site than at the other two sites. In contrast, a tendency towards a larger distance was seen from the skin to trapezius muscle at the medial measuring site than at the other two sites. No statistical differences were found between the two groups of subjects either at rest or during brief shoulder abductions. All the subjects performed a 30 degrees unilateral isometric shoulder abduction test to exhaustion. The median endurance time was 33 min for the healthy subjects and only 5 min for the patients. The ratings of perceived exertion (RPE) were in line with this, since the increment in RPE with time was larger for the patients than for the healthy group. The reduced shoulder abduction endurance time in the patient group may have been related to impaired muscle function and/or pain development. During the 33-min shoulder abduction in the healthy subjects, the thickness of supraspinatus muscle increased by 14%, indicating muscle swelling, whereas the thickness of trapezius muscle remained constant.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗

PubMed1993

Shoulder muscle load and muscle fatigue among industrial sewing-machine operators.

Physiological responses to physical work were assessed for 29 female industrial sewing-machine operators during an 8-h working day under ordinary working conditions. During sewing-machine work, the average (left and right) static load in the trapezius muscle was 9% of the maximal electromyogram (EMG) amplitude (% EMGmax), while the average mean load was 15% EMGmax, and the average peak load was 23% EMGmax. The static load level was unrelated to the muscle strength of the sewing-machine operators, which for the group as a whole was within the normal range. The load levels remained unchanged during the working day, while changes in the EMG mean power frequency and zero crossing frequency rate occurred, both indicating the development of muscle fatigue in left and right trapezius muscle during the working day. In line with this, the rating of perceived exertion in the shoulder and neck region increased during the working day. Dividing the group of sewing-machine operators into two groups, those with the highest frequency and those with the lowest frequency of shoulder/neck troubles showed that the former group had significantly lower muscle strength, despite the fact that no differences in the surface EMG during sewing were found between the two groups. It was concluded that industrial sewing-machine work involves a pattern of shoulder muscle activity which induces fatiguing processes in the shoulder and neck regions. Furthermore, since the static shoulder muscle load was independent of muscle strength, factors other than working posture may be of significance for the static shoulder muscle load.

Adult↗

PubMed1993

Plasma potassium concentration and doppler blood flow during and following submaximal handgrip contractions.

The aim of the present study was to investigate the time-course of blood velocity in the forearm during and following isometric handgrip contractions and to reveal a possible temporal relationship between the circulatory response and venous effluent potassium concentration ([K]) not only during contractions but also during the post-exercise recovery period. Contractions of 15% maximal voluntary contraction (MVC) and 30% MVC with and without 3 min of arterial occlusion following the contractions were studied. All contractions induced a significant increase in venous plasma [K] from an average resting level of 4.0 to 5.0 mM during 15% MVC and 5.8 mM during 30% MVC. Blood velocity increased from a resting level of 0.07 to 0.22 m s-1 and 0.36 m s-1 during 15% and 30% MVC, respectively. MVC of 30% always elicited a larger blood velocity and [K] response than 15% MVC. Following the contractions hyperaemia was elicited. Recovery of the local blood velocity was markedly slower than the K recovery, since [K] remained significantly above resting level for only 25 s following 15% MVC and 45 s following 30% MVC, while blood velocity remained elevated for 2 min and more than 7 min following 15 and 30% MVC, respectively. Further, a larger hyperaemia following the occlusion was elicited as compared to the contraction without occlusion, in spite of [K] being lower immediately after the occlusion period than immediately after the contraction. Finally, [K] decreased below resting level in the recovery period while the blood velocity remained elevated. Therefore, the present study showed that the venous plasma [K] is not causally related to the prolonged post-exercise hyperaemia. The skin temperature remained unchanged during the contractions, while during the recovery period the skin temperature increased for several minutes. The major part of the temperature increase was likely to be due to conductance of heart from muscles to skin surface as a consequence of muscle hyperaemia.

Adult↗

PubMed1992

Ultrasound image of human masseter muscle related to bite force, electromyography, facial morphology, and occlusal factors.

The thickness of the human masseter muscle, corresponding approximately to a cross-section at the most bulky part of the superficial portion, was measured by ultrasound scanning at three sites 1 cm apart. The study included 13 women, 21-28 yr of age, with a minimum of 24 teeth and without craniomandibular disorders. Ultrasonography produced a well-defined depiction of the muscle with distinct tendinous structures. The average thickness at the measuring sites varied from 8.83 to 11.08 mm with the muscle relaxed, and increased significantly during contraction to average values between 9.84 and 12.57 mm. The study showed a connection between measures of masseter thickness and function of the muscle, as well as parameters generally associated with masseter muscle function. Muscle thickness at the voluminous anterior part of the superficial portion was systematically and significantly correlated to bite force, occlusal tooth contact and cephalometric data (anterior face height, vertical jaw relation and mandibular inclination). In conclusion, ultrasound scanning gave an uncomplicated and a reproducible access to parameters of jaw muscle function and its interaction with the craniomandibular system.

Adult↗

PubMed1992

Role of potassium in the reflex regulation of blood pressure during static exercise in man.

1. The relationship between [K+] in venous effluent blood and alterations in mean arterial blood pressure was studied during static handgrip contractions at 15 and 30% of maximal voluntary contraction (MVC). 2. To further elucidate the importance of K+ in the reflex regulation of blood pressure a situation with normal recovery was compared with a situation in which 3 min of post-exercise occlusion was applied by arresting the circulation to the forearm just prior to the cessation of the contraction. 3. There was a temporal as well as quantitative correlation between venous [K+] and the blood pressure response during and after static exercise. During 30% MVC mean arterial blood pressure (MAP) attained 161.7 mmHg and venous [K+] 5.8 mM, while the corresponding values during 15% MVC were 121.5 mmHg and 5.0 mM. 4. In the occlusion period mean arterial blood pressure remained elevated above resting level and provided a measure of the magnitude of muscle chemoreflexes. In the same period venous [K+] was maintained at 5.3 mM and 4.6 mM following 30% MVC and 15% MVC respectively. This is indicative of interstitial concentrations of above 8-10 mM. This level is sufficiently high to stimulate type III and IV muscle afferents involved in the reflex regulation of blood pressure, and strengthens the notion that K+ may play an important role in eliciting the pressor reflex. 5. In contrast to [K+] the time course of venous blood concentrations of lactate and ammonia (NH3) exhibited a clear dissociation from the blood pressure recordings.

Adult↗

PubMed1990

Cloning of aldB, which encodes alpha-acetolactate decarboxylase, an exoenzyme from Bacillus brevis.

A gene for alpha-acetolactate decarboxylase (ALDC) was cloned from Bacillus brevis in Escherichia coli and in Bacillus subtilis. The 1.3-kilobase-pair nucleotide sequence of the gene, aldB, encoding ALDC and its flanking regions was determined. An open reading frame of 285 amino acids included a typical N-terminal signal peptide of 24 or 27 amino acids. A B. subtilis strain harboring the aldB gene on a recombinant plasmid processed and secreted ALDC. In contrast, a similar enzyme from Enterobacter aerogenes is intracellular.

Amino Acid Sequence↗

PubMed1989

Complete amino acid sequence of alpha-acetolactate decarboxylase from Bacillus brevis.

The complete amino acid sequence of acetolactate decarboxylase (EC 4.1.1.5) from Bacillus brevis has been determined by sequencing of the intact enzyme and of peptides obtained by cleavage with cyanogen bromide, Staphylococcus aureus V8 protease and trypsin, respectively. Determination of the C-terminal part was made by treatment with carboxypeptidases Y and M II. The enzyme has a molecular weight of 29,093 and consists of 260 amino acid residues arranged in a single peptide chain without disulphide bonds.

Amino Acid Sequence↗