PubMed Health⌕ Search

Biomedical subjects

J F Ditunno

Publications and source records attributed to J F Ditunno.

At least 109 records · Page 6Linked to original sources
PubMed1980

Marked bone spur formation in a burn amputee patient.

This report presents an unusual case of a lower extremity burn amputee with a marked degree of bone spur formation. A 17-year-old man suffered 56% body surface area mixed-depth electrical and flame burns, necessitating left below knee amputation. He was admitted to a rehabilitation center 3 months postinjury for pylon fitting and gait training. Difficulty was encountered with poor skin tolerance to weight bearing because of the prominent distal bony margins in the stump. X-rays of the stump revealed a marked degree of linear bone spur formation, extending longitudinally from the distal tibia and fibula with multiple cross-bridges. The spur formation was considered an extensive bony exostosis of unclear etiology. Surgical revision was elected to obtain a stump more suitable for prosthetic tolerance, and to avoid a bulky "bypass" prosthesis. This stump revision enabled the patient to attain independent functional prosthetic ambulation. Although there is evidence of some recurrence of bone spur formation, this remains limited and asymptomatic.

Adolescent↗
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↗
PubMed1974

Effect of swimming on reinnervation of rat skeletal muscle.

There are no studies that define the optimum intensity or time to begin exercising reinnervating muscle. Through overwork of reinnervating muscle, accomplished by synergistic tenotomy, we developed a working hypothesis. This hypothesis was tested on a physiological model. In the present study, the sciatic nerve of five groups of rats was crushed. One group served as the control and the remaining animals were exercised by swimming with weights attached to their tails for one or two hours each day (early reinnervation group) or four weeks (late reinnervating group) after crush denervation. The evaluation of muscle weights, fibre types, and protein concentration indicate that intense swimming (two hours every day) does not enhance the repair of reinnervation muscle. An evaluation of total proteins suggests that a high workload may be hazardous in the early phase of reinnervation. This study tends to confirm the hypothesis that when there are too few contractile units, as presumably is the case in early reinnervation, exercise inhibits the reinnervation process.

Animals↗