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Biomedical subjects

M M Jaweed

Publications and source records attributed to M M Jaweed.

At least 37 records · Page 2Linked to original sources
PubMed1983

Compensatory hypertrophy of the soleus in tumor-bearing rats.

Compensatory hypertrophy of the rat soleus was compared between normal rats (N) and rats bearing a non-metastasizing mammary tumor (TB). Two weeks after the tumor inoculation, introduced subcutaneously on the midline of the upper back, the two groups of rats underwent unilateral tenotomy of the plantaris and gastrocnemius muscles to induce functional overload or compensatory hypertrophy of the soleus. One week later, the body weight (BW), wet muscle weights (MW), percent of Type I (slow-twitch) and Type II (fast-twitch) muscle fibers and contractile parameters of the isometric twitch (Pt) and tetanic (Po) tensions were evaluated. The TB animals did not show any signs of cancer cachexia. The sham-operated control soleus muscles of the two groups were similar in wet MW, maximum isometric Pt and Po. The latent period (LP), the contraction time (CT), the half relaxation time (HRT) and the number of Type I (slow-twitch) fibers were increased significantly. The hypertrophied muscles in the N and TB rats showed significant declines in the maximum isometric Pt, compared to their respective controls. These data suggest that the compensatory hypertrophy of muscle is expressed similarly in both the normal and tumor-bearing rats but that it interferes with the generation of isometric twitch tension in the muscle.

Adaptation, Physiological↗
PubMed1983

Exercise therapies in peripheral neuropathies.

The treatment of peripheral neuropathies should be aimed at maintaining the range of motion of the joints, re-educating the patient in skilled activities and optimizing the recovery of strength. Many techniques have been described to substitute for, to strengthen and to improve the function of residual innervated muscle; however, not all of these techniques are of unquestioned value. Specifically, electrical stimulation does not appear to enhance reinnervation of totally denervated muscle. Similarly, overstretching weakened muscle may impair the use of paretic muscle. Because overwork may damage partially denervated muscle, brief isometric or isotonic contractions may be more beneficial for increasing strength than a program of habitual exhausting activities.

Cold Temperature↗
PubMed1983

Acetylcholine sensitivity and fibrillation potentials in electrically stimulated crush-denervated rat skeletal muscle.

Juxtamuscular electrodes were implanted unilaterally in six groups of adult female Wistar rats to evaluate the effect of chronic electrical stimulation (ES) during denervation and reinnervation of the rat soleus muscle. Two weeks later, the animals underwent bilateral crush-denervation of the sciatic nerve at the sciatic notch. Six additional groups served as normal controls. The soleus muscles in the crush denervated and control groups were stimulated unilaterally with a 4mA, 4msec duration current given at 10Hz continuously 8 hours each day for 5, 10, 15, 20, 25 or 30 days. At the end of each period, the soleus muscles were evaluated for the muscle weights, acetylcholine (ACh) sensitivity and fibrillation potentials (FPs). The normal muscles were unaffected by the stimulation. The denervated-stimulated soleus muscles were heavier at 10 days (p less than 0.05) and had fewer FPs after 5 to 15 days (p less than 0.01) of electrical stimulation than their matched denervated controls. The ACh sensitivity throughout the experimental period and the fibrillatory activity from 20 to 30 days post-crush were similar in the denervated and the denervated-stimulated muscles. In conclusion, ES reduced the degree of atrophy and the number of fibrillations of the soleus muscle in the denervation stage. However, it neither enhanced nor impaired the reinnervation of muscle.

Acetylcholine↗
PubMed1982

Changes in thromboxane B2 and 6-keto-PGF1 alpha after direct electrical stimulation of the denervated rat gastrocnemius1,2.

Radio-immunoassay was used to measure the amounts of Thromboxane B2 (TXB2) and 6-keto-PGF1 alpha produced in the gastrocnemius muscles of rats after denervation and direct electrical stimulation (2-4 mA intensity and 4 msec duration pulses given at 10 Hz continuously, 8 hours each day for 14 days). Compared to the normal control side, the normal-stimulated, the denervated control and the denervated-stimulated muscles, all indicated increases in the content (ng/g muscle) of TXB2 (120-155%, P less than 0.01) and 6-keto-PGF1 alpha (90-10 7%). This study suggests that electrical stimulation as well as denervation may lead to an elevation of these prostanoids.

6-Ketoprostaglandin F1 alpha↗
PubMed1982

Muscle fiber types.

This review describes muscle fiber types based on their histochemical, ultrastructural, biochemical, and physiologic properties. Reportedly the speed of muscle fiber contraction is directly proportional to relative myosin ATPase activity (at pH 9.4) while fatigability relates to relative oxidative capacity. Type I fibers have low ATPase activity (at pH 9.4), are slow twitch, have high oxidative and low glycolytic capacity, and are relatively resistant to fatigue. Type IIA fibers have high myosin ATPase activity (pH 9.4), are fast twitch, have high oxidative and glycolytic capacity, and are relatively resistant to fatigue. Type IIB fibers have high myosin ATPase activity (pH 9.4), are fast twitch, have low oxidative and high glycolytic capacity, and fatigue rapidly.

Adenosine Triphosphatases↗
PubMed1982

Physical activity and inactivity influences on 14C-leucine incorporation in reinnervated rat gastrocnemius.

The influence of activity and inactivity in reinnervated gastrocnemius muscles of adult rats was evaluated by measuring muscle mass, sarcoplasmic proteins (SP), myofibrillar proteins (MP), and 14C-leucine incorporation. Both sciatic nerves were crushed in 18 adult female Wistar rats, 6 of which were exercised daily on a 35% grade treadmill at a running speed of 27 m/min, 6 others underwent bilateral cast-immobilization of the ankle, knee, and hip joints at 90 degrees, and 6 were kept as sedentary controls between 2 and 6 weeks after denervation. During this period, all animals received daily an injection of 0.2 ml of 14C-leucine (sp. activity 51.4 muCi/mM). The exercised rats had similar muscle mass, but significantly increased in both MP and 14C-leucine incorporation, when compared to the sedentary rats. In contrast, the cast-immobilization group showed significant decreases in muscle weight and 14C-leucine incorporation in SP. These results suggest that activity enhances the apparent synthesis of MP in reinnervating muscles, but does not indicate that inactivity interferes with or limits the process of reinnervation by impeding the synthesis of SP or MP.

Animals↗
PubMed1982

Reinnervating rat skeletal muscle: effect of 35% grade treadmill exercise.

To determine the effect of 35% grade treadmill running on reinnervating rat skeletal muscle, adult rats were exercised for 1 hour on a 35% grade motorized treadmill, at a speed of 27m/min, once and twice daily, 5 days a week from the 3rd to the 6th week after sciatic nerve crush. Compared to the crush denervated control, the crush-denervated-twice exercised group decreased in the content of sarcoplasmic proteins (15.2%, p less than 0.05), and in the contraction time of the soleus (8.9% p less than 0.05). The percentage of type II fiber types in the plantaris increased 15% (p less than 0.05) in the once and 10% (p less than 0.05) in the twice daily exercised group. The findings of this study suggest that treadmill training performed during reinnervation did not cause muscle damage and may have increased the "fast" type muscle properties in the rat skeletal muscle.

Animals↗
PubMed1981

Response of type I fibers to weight lifting in rat plantaris.

The purpose of this histochemical study was to determine the effect of weight lifting exercise training on the muscle fibers in 2 muscle regions of the rat plantaris. Adult female Wistar rats were trained to carry weights up to 150 gm on their backs, up a 50 degrees incline, for a period of 6 weeks. A comparison between the exercised and control groups showed no significant muscle hypertrophy or change in the number of fibers. Only the smallest muscle fibers, which are located predominantly in the superficial region of the plantaris, showed a significant increase (19.6%, p less than 0.01) in diameter. The data suggest that the smallest muscle fibers, in the superficial region of the plantaris in this weight lifting training program, were exercised out of proportion to their usual activity and responded to the stress of the activity by enlarging.

Animals↗
PubMed1981

Contractile properties of reinnervating skeletal muscle in the rat.

The purpose of this study was to determine the isometric twitch tension (Pt), isometric tetanic tension (Po), and twitch contraction time (Ct) of the reinnervating rat soleus and plantaris muscles. Six groups of adult female Wistar rats (200 to 225 gm BW) underwent bilateral sciatic nerve crush at the sciatic notch, while another 6 groups were kept as sham-operated normal controls. The contractile properties of the muscles from the normal and crush-denervated groups (n=6-9) were determined in vitro weekly, at 0, 1, 2, 3, 4, 5, and 6 weeks, post-nerve crush. The muscle were equilibrated in a polyglass cell in oxygenated Ringer's solution at pH 7.2 at 34-35 C. The muscles were field stimulated at optimal length (Lo) to produce maximal Pt, using 15-20 v, 5 amp current, at 0.2 Hz for 1 msec duration. Following twitch determinations, the muscles were tetanized at 200 Hz. All tension values were expressed per unit area of the muscle. The respective control tension per area values for the soleus and plantaris were: Pt, 3.3 +/- 0.4 gm, 5.9 +/- 0.4 gm; Po, 20.7 +/- 5.1 gm, 21.8 +/- 4.8 gm, while the Ct values for the soleus and plantaris were 37.6 +/- 2.1 msec and 16.3 +/- 1.1 msec, respectively. At 3 weeks post-nerve crush, the crush-denervated soleus Pt and Ct increased 40% and 33.6% respectively, and the plantaris 28.2% at 1 week after the nerve was crushed. Gradual recovery was noted in the Pt and Ct from the 4th to 6th weeks post-crush, while the Po began improving 1 to 2 weeks after denervation. The soleus Pt and Po appeared to be more dependent on neural control than the plantaris muscle. During reinnervation, the slow soleus and fast plantaris Ct were equally dependent on innervation. Reinnervation prompted changes in the Po, Pt, and Ct, suggesting that regenerating neurons promote a sequential emergence of normal contractility.

Animals↗
PubMed1980

Histochemical fiber type alterations secondary to exercise training of reinnervating adult rat muscle.

The purpose of this study was to evaluate the effect of exercise training on reinnervating rat muscle histochemistry. Adult female Wistar rats in 5 groups (1 control and 4 experimental) underwent bilateral sciatic nerve crush. The 4 experimental groups were exercised on a motorized treadmill at 35% grade and a speed of 27m/min once (groups J and L) or twice (groups K and M) daily, 5 days/week from the 2nd (groups J and K), and 3rd (groups L and M), to the 6th week after the crush. The exercise sessions lasted 1 hour. The fiber diameter and percent of type I and II fibers (weak and strong myosin ATPase reaction, pH .94) were evaluated in the soleus and superficial and deep regions of the plantaris muscles. Exercise training did not affect the fiber diameters. There was no change in the fiber type distribution in the soleus and superficial region of the plantaris. However, the percent of type II fibers increased significantly (p less than 0.05) in the deep region of the plantaris groups J, K, L and M bu 12%, 7%, 15% and 10%, respectively. This study indicated that exercise did not interfere with reinnervation and that there was an increase in the proportion of fibers with a strong myosin ATPase reaction in the deep region of the plantaris.

Adenosine Triphosphatases↗
PubMed1979

Muscle atrophy in rats following denervation, casting, inflammation, and tenotomy.

One week after unilateral denervation, tenotomy, casting, or joint inflammation, skeletal muscles of adult female Wistar rats were studied to determine the effect of these processes on muscle weights and fiber diameters of the soleus, the red and white regions of the plantaris, plus muscle weights and protein content of the gastrocnemius. All atrophic processes caused greater weight loss of the soleus than of the plantaris or gastrocnemiums. Within the soleus and plantaris muscles, the type-I fiber atrophy was equal to the type-II fiber atrophy except for the white region of the plantaris following tenotomy, where the wasting of the type-I fiber was greater than that of type II. This study also demonstrated that denervation, tenotomy, casting, and inflammation resulted in a greater loss of myofibrillar proteins (content and absolute amounts) than of sarcoplasmic and stromal proteins. Denervation generally was found to have the greatest effect on the parameters evaluated. The findings are consistent with the hypothesis that slow muscle is more dependent than fast muscle on neuronal control, and that nerve controls muscle through the dual role of impulse activity and axoplasmic flow.

Animals↗
PubMed1978

Muscle fiber atrophy after cast immobilization in the rat.

The purpose of this study was to evaluate the effect of 6 weeks of bilateral cast immobilization on the adult Wistar rat plantarflexors. Knee and ankle joints were fixed in the neutral position, under sodium pentobarbital anesthesia. Controls (n = 7) and cast-immobilized (n = 7) rats were sacrificed at 6 weeks after the onset of the experimental period. The muscles were evaluated for muscle weight, protein content, and fiber histochemistry. There was equal weight loss in the gastrocnemius, soleus, and plantaris muscles, and greater loss of myofibrillar protein than of sarcoplasmic protein concentrations. Fiber atrophy of types I and II was equal in the soleus, and that of type II was greater than the type I atrophy in both regions of the plantaris. All soleus and 2 plantaris muscles demonstrated fiber damage. The results of this experiment suggest that the degree of fiber atrophy is specific to the fiber type and to its location in different muscles or muscle regions.

Animals↗
PubMed1977

Myosin ATPase activity after strengthening exercise.

Alteration in the histochemical activity of myosin ATPase has been demonstrated in the soleus of adult rats after brief (A) and prolonged (B) intensive weight lifting exercises. The former represented 'high intensity-short duration' and the latter 'high intensity-prolonged duration' exercise. The data revealed a significant muscle hypertrophy (23-26%) in both the exercising groups. Whereas group A muscles showed a relative increase in the number of type II (FOG) fibres, accompanied by a hypertrophy of the type I or slow twitch-oxidative (SO) fibres, the soleus muscles in group B showed a significant decrease (P less than 0.01) in the number of type II (FOG) fibres, presumably owing to a conversion of type II (FOG) to type I (SO) fibres. It is hypothesized that strengthening exercise may enhance the activity of the 'fast type' of myosin ATPase in brief or static work, and the 'slow type' in prolonged or more dynamic high intensity work.

Adenosine Triphosphatases↗
PubMed1975

Denervation and reinnervation of fast and slow muscles. A histochemical study in rats.

A histochemical study, using myosin-adenosine triphosphatase activity at pH 9.4, was conducted in soleus and plantaris muscles of adult rats, after bilateral crushing of the sciatic nerve at the sciatic notch. The changes in fiber diameter and per cent composition of type I and type II fibers plus muscle weights were evaluated along the course of denervation-reinnervation curve at 1, 2, 3, 4 and 6 weeks postnerve crush. The study revealed that in the early denervation phase (up to 2 weeks postcrush) both the slow and fast muscles, soleus and plantaris, resepctively, atrophied similarly in muscle mass. Soleus increased in the number of type II fibers, which may be attributed to "disuse" effect. During the same period, the type I fibers of soleus atrophied as much or slightly more than the type II fibers; whereas the type II fibers of plantaris atrophied significantly more than the type I fibers, reflecting that the process of denervation, in its early stages, may affect the two fiber types differentially in the slow and fast muscles. It was deduced that the type I fibers of plantaris may be essentially different in the slow (soleus) and fast (plantaris) muscles under study. The onset of reinnervation, as determined by the increase in muscle weight and fiber diameter of the major fiber type, occurred in soleus and plantaris at 2 and 3 weeks postcrush, respectively, which confirms the earlier hypotheses that the slow muscles are reinnervated sooner than the fast muscles. It is suggested that the reinnervation of muscle after crush injury may be specific to the muscle type or its predominant fiber type.

Adenosine Triphosphatases↗
PubMed1975

Synergistic tenotomy: effect on chronically denervated slow and fast muscles of rat.

A study was conducted with chronically denervated adult female Wistar rats to test the hypothesis that synergistic tenotomy of denervated skeletal muscles does not just retard atrophy but produces an increase in muscle weight. The animals were categorized in three groups-denervated exercised (DE), denervated tenotomized (DT), and denervated-tenotomized-exercised (DTE). Mechanical stretch was induced in the DE group by forcing the animals to stand on their hind legs to reach for food and water. In the DT group, mechanical stretch was induced by tenotomy of two synergists in the gastrocnemius-plantaris-soleus complex of each leg of the rat so that either the soleus or the plantaris was left as the only plantar-flexor of the ankle joint in each leg. Mechanical stretch was induced in the DTE group by forcing the animals to stand after the tenotomy of synergists at eight weeks postdenervation. All animals in the three experimental groups, and in the sedentary control group (D) were sacrificed at nine weeks postdenervation; the soleus and plantaris muscles were removed and evaluated for MW, DW and percent of hydration. The slow muscle (soleus) increased in muscle mass in DT (53%), DE (26%), and DTE (17%). The fast muscle (plantaris) increased in weight in DE (18%) and in DTE (24%), but showed no significant changes in DT. Study results confirm the hypothesis that synergistic tenotomy stimulates an increase in muscle weight rather than merely retarding atrophy, and that this phenomenon can take place in the absence of neuronal influences. It is suggested that the increase in denervated muscle mass stimulated by muscle elongation is not a true work hypertrophy associated with significant changes in protein concentrations but only an adaptation to a new muscle length. The purpose of the adaptational changes is to optimize the overlap of actomyosin bridges in anticipation of forceful muscle contraction.

Animals↗