Hiromu Shoji

The synergistic action of the anterior cruciate ligament and thigh muscles in maintaining joint stability

The synergistic action of the ACL and the thigh muscles in maintaining joint stability was studied experimentally. The EMG from the quadriceps and hamstring muscle groups was recorded and analyzed in three separate experimental procedures in which the knee was stressed. The test revealed that direct stress of the ACL has a moderate inhibitory effect on the quadriceps, but simultaneously it directly excites the hamstrings. Similar responses were also obtained in patients with ACL damage during loaded knee extension with tibia subluxation, indicating that an alternative reflex arc unrelated to ACL receptors was available to maintain joint integrity. The antagonist muscles (hamstrings) were clearly demonstrated to assume the role of joint stabilizers in the patient who has a deficient ACL. The importance of an appropriate muscle-conditioning rehabilitation program in such a patient is substantiated.

FACTORS AFFECTING POSTOPERATIVE FLEXION IN TOTAL KNEE ARTHROPLASTY

In the review of 67 cases with total condylar (TC) prostheses, 59 with TC posterior stabilizers, 70 with TC prostheses modified with flat posterior tibial plateau, and 35 with porous-coated arthroplasty (PCA) prostheses, multiple cross-examinations of various factors for postoperative flexion were performed. Follow up was 2 to 9 years. In nearly all cases, no further improvement of flexion was noted after 1 year following surgery. The most influential factor for good postoperative flexion was intense physical therapy, leading to good suprapatellar pouch reconstitution. Residual flexion contracture was more frequent when the posterior cruciate ligament (PCL) was retained in the cases with significant preoperative flexion contracture. However, retention of PCL or preoperative ACL condition did not bear any significance to the ultimate flexion.

Cruciate retained and excised total knee arthroplasty. A comparative study in patients with bilateral total knee arthroplasty.

A comparative study of posterior cruciate ligament retention and excision was conducted in patients who underwent bilateral total knee arthroplasty using the total condylar modifier prosthesis. The posterior cruciate ligament was excised in one knee and was retained in the other knee in 28 patients. Postoperative results were assessed using the Hospital for Special Surgery Knee Evaluation Score. In addition, stair activity was tested to determine whether there was preferential dependence on one of the two knees. There was no significant difference between the posterior cruciate ligament retained or excised knees in terms of postoperative Hospital for Special Surgery Knee Evaluation Score. Patients who ascended and descended stairs with one leg at a time tended to prefer the posterior cruciate ligament retention side. Those who could use each leg in sequence to go up and down stairs, however, did not show preferential dependence on either knee.

Identification of Fibronectin in Preparations of Osteoarthritic Human Cartilage

Several high molecular weight proteins were observed in dissociative extracts of osteoarthritic, but not of normal, human cartilage. By gel electrophoresis, by DEAE-cellulose and gelatin-agarose chromatography, and immunologically, they were found to be identical to fibronectin. Incorporation of tritiated proline into these proteins indicated that this material was not a synovial fluid contaminant. Interactions with the proteoglycans suggested that, in articular cartilage, the role of fibronectin may be more closely associated with proteoglycans than with collagen. The appearance of fibronectin in the diseased cartilage suggests that this may be a feature of the chondrocytes repair response to the loss of extracellular matrix.

A technique for recording the EMG of electrically stimulated skeletal muscle.

A technique for recording the myoelectric activity of electrically stimulated muscle through its motor nerve without the interference of stimuli artifacts has been developed and tested. The technique consists of a wide band differential amplifier with fine intramuscular wire electrodes. The amplified signal is passed through a Chebyshev low pass filter with eight poles at a frequency of 550 Hz. A stimulus calibration study shows that low frequency stimuli had negligible effect on the EMG when set below three times suprathreshold. A test procedure shows artifact-free EMG during action potential rate stimulation as well as during superimposed high frequency recruitment stimulation.

The Effect of Prenatal Protein-Energy Malnutrition on Collagen Metabolism in Fetal Bones

We analyzed various biochemical variables of the bones in fetal rats whose dams were protein-energy malnourished. Dams were randomly divided into two groups and fed either a 6% protein diet as a malnourished group or a 20% protein diet as a control, from day 13 of gestation to day 22, when fetuses were removed. Hexosamine and hydroxyproline contents of the calvaria and hexosamine contents of long bones were greater in the malnourished group than in the controls. Sequential extractability of collagen differed among various bones in the malnourished group and controls. The ratio of alpha:beta obtained from SDS-polyacrylamide gel of neutral salt-soluble collagen tended to increase in the long bones and mandible, and decrease in the calvaria and ribs in the malnourished group. Also, the ratio of alpha 1:alpha 2 tended to be lower in the malnourished group than in the control group in all bones. Protein-energy malnutrition during pregnancy has shown to affect biochemical composition of various fetal bones.

Effects of excess methionine on collagen metabolism: A study on newborn rat skin

We studied the biochemical effects of excess methionine intake on the skin of newborn rats. Group 1 pups were intubated with methionine dissolved in 0.1 ml physiological saline solution in the amount of 0.1 g/100 body wt as a control using a gastric needle. Group 2 pups were given 0.2 g/100 g in the same manner as group 1 as an experimental group. They were intubated every other day from day 3 to 13. On Day 15, [14C]proline was injected intraperitoneally into pups and their skin was removed. 14C total and hydroxyproline uptake was examined in the tissue as well as in the sequential extracts. Although excess methionine intake by the pups did not alter the collagen content of their skin, it caused an increase in the content of type III collagen and a decrease in crosslinked collagen. In addition, newly synthesized collagen in the neutral salt extract increased in the excess methionine group, indicating that crosslinked collagen decreases as excess methionine was intubated. The present study demonstrated that excess methionine in the early lactational period altered the nature of the skin collagen of suckling newborn rat pups.

Biochemical changes of the skin in protein-energy malnourished lactating rats and their pups

Abstract We analyzed various biochemical variables of the skin on rat dams and their suckling pups under protein-energy malnutrition. Dams and pups were divided into three groups according to the percentage of casein in diet: 20% (control), 12%, and 6% groups. In the pups skin, hydroxyproline, noncollagenous protein, and hexosamine contents in the 6% and 12% groups were greater than those in the control, although water content in the 6% group was less than that in the other groups. In the dams skin, the amount of hydroxyproline in the 12% group was less, whereas that of noncollagenous protein was greater than that in the other groups. Hexosamine content did not differ among these groups. Water content of the dams was increased according to the degree of malnutrition. In the skin of mothers and pups, cross-link formation of collagen was decreased in proporation to the degree of malnutrition. In the pups the content of type III was decreased in the 6% and 12% groups, whereas in the mother it increased only in the 6% group. These results show that protein-energy malnutrition significantly influences the metabolism of the skin in the pups and their lactating mothers, but lism of the skin in the pups and their lactating mothers, but not necessarily with the same effects. Furthermore, the skins of pups and their mothers respond dissimilarly to the degree of malnutrition.

THE EFFECTS OF PRENATAL PROTEIN-ENERGY MALNUTRITION ON OSSIFICATION OF FETAL RAT BONES: A BIOCHEMICAL STUDY

In fetal rats whose dams were fed a low-protein diet, 35S sulfate uptake into the growth plate of the long bone and rib was higher than in the control group. The elution pattern of guanidine-HCl extract in gel chromatography revealed that the malnourished group had more high molecular weight proteoglycans in the dissociative condition and a larger aggregated portion in the associative condition than did the control group; however, the same chondroitin-sulfate chain size existed. Calcium content did not differ in both groups. Aggregated proteoglycan or a high molecular weight proteoglycan that existed in the malnourished group probably played an inhibitory role in calcification. Prenatal protein-energy malnutrition may delay the change of proteoglycan character, which could affect mineralization of fetal bones.

Prenatal Protein-Energy Malnutrition Alters Various Biochemical Components of the Membranous Bones in Fetal Rats

The effects of prenatal protein-energy malnutrition on the biochemical parameters of the membranous bone were studied using fetal rats. Timed pregnant rats were fed a protein-deficient diet as an experimental group from day 13 of gestation, whereas control dams were fed a normal protein diet. By day 15, radioactive Na2SO4 was injected. On day 22, all fetuses were delivered by cesarean section. The hexosamine content per milligram dry tissue, and the protein and hexosamine contents per guanidine-HCl extract were greater in the mandibles but less in the calvaria of the malnourished group than in those of the controls. Calcium content per gram dry tissue was lower in both bones of the malnourished group. 35S-sulfate uptake per milligram dry tissue or milligram proteoglycan was greater in the malnourished group than in the controls in both bones. The mandible in the malnourished group had less lower-weight molecular proteoglycan subunits in the dissociative condition. Protein-energy malnutrition affects the mandible and calvaria in different ways, although both bones originate from membranous bone. Insufficient degradation of proteoglycan could be the reason for the delay of mineralization in the malnourished bones.