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Biomedical subjects

M J Stuart

Publications and source records attributed to M J Stuart.

At least 145 records · Page 8Linked to original sources
PubMed1976

Malabsorption of iron in children with iron deficiency.

Inability to absorb oral iron is believed to be an extremely rare cause of therapeutic failure in the treatment of iron deficiency anemia. Six patients who had failed to respond to oral iron therapy were studied by a simple oral absorption test and contrasted with 25 patients with untreated iron deficiency anemia and 10 normal subjects. All six of the patients who were therapeutic failures demonstrated impaired iron absorption in the absence of other clinical evidence of gastrointestinal disease. In the 25 newly diagnosed patients with iron deficiency. 24 demonstrated elevated iron absorptions while 10 ironreplete normal subjects had minimal elevations in their serum iron values following the administration of the test dose of 1 mg of elemental iron per kilogram. When the therapeutic failures were treated with parenteral iron, all had a therapeutic response. In addition, after treatment the impaired absorption of iron improved transiently. All children who absorbed iron readily responded to oral iron therapy.

Administration, Oral↗
PubMed1975

A simple nonradioisotope technic for the determination of platelet life-span.

Acetylsalicylic acid was shown both in vivo and in vitro to prevent the platelet lipid peroxidation normally induced by the aggregating agents thrombin and epinephrine, and the sulfhydryl inhibitor N-ethylmaleimide. After aspirin ingestion, there was a significant reduction (p smaller than 0.005) in platelet lipid peroxidation, with a gradual return to base-line values over a 10-day period. With these values, a normal platelet survival curve was constructed with a mean half-life of 4.4 days (range of 2.9 to 5.9 days). These values agree with the standard 51-Cr survivals in three patients with chronic idiopathic thrombocytopenic purpura. Half-lives of 1.0, 2.5, and 4.1 days by lipid peroxide technic compared with 1.9, 2.5, and 3.9 days by the concurrent use of 51-Cr. Thus, the technic may be used to measure platelet survival.

Aspirin↗
PubMed1975

Iron deficiency anemia and increased urinary norepinephrine excretion.

Chronic iron deficiency in rats resulted in decreased MAO activity both in vitro and in vivo. Since MAO is an important enzyme in inactivation of catecholamines, urinary excretion of DA, NE, E, MN-NMN, and VMA was measured in 24-hour samples from 11 iron-deficient children before and after treatment with intramuscular iron. Pretreatment NE excretion was abnormally high and returned to normal (P=0.001) within one week of therapy. VMA excretion also was higher before than after treatment (P greater than 0.05), but most values were within the normal range for healthy children of comparable size. There was no significant difference between DA, E, and MN-NMN excretion before and after iron therapy. Anemic, non-iron-deficient children had normal urinary NE, E, and VMA excretion before and after transfusion. These findings suggest that the irritability, lack of attentiveness, and low performance scores of iron-deficient children may be related to alterations in catecholamine metabolic pathways secondary to dependence of MAO on adequate iron stores.

Adolescent↗
PubMed1975

Syndrome of recurrent increased secretion of antidiuretic hormone following multiple doses of vincristine.

The syndrome of inappropriate antidiuretic hormone secretion (SIADH) has been recognized to occur following treatment with vincristine. None of the reports have provided information regarding its potential for recurrence on further challenge with vincristine (VCR), an agent generally required for repeated use in patients with malignancies. Symptomatic hyponatremia and SIADH that occurred 8 days following administration of VCR in a child with acute lymphatic leukemia was documented with specific radioimmunoassay of urinary ADH levels. The further occurrence of recurrent elevations in ADH excretion 8-10 days following repeated treatment with VCR was also observed. However, SIADH was prevented by prophylactic rigorous fluid restriction. The occurrence of SIADH following VCR therefore does not preclude the further safe usage of this drug.

Child, Preschool↗
PubMed1975

The measurement of free erythrocyte porphyrin (FEP) as a simple means of distinguishing iron deficiency from beta-thalassemia trait in subjects with microcytosis.

Assay of free erythrocyte porphyrin (FEP) and measurement of red cell indices were obtained in a group of subjects with iron deficiency and beta-thalassemia trait to determine if these studies cound detect these disorders and discriminate bbetween them. FEP values were increased in 90.2 per cent of subjects with iron deficiency but were within the normal range in 96.6 per cent of subjects with beta-thalassemia trait. Mean FEP values increased sligtly as transferrin saturation fell but became abnormally elevated when the transferrin saturation fell but became abnormally elevated when the transferrin saturation was less than 15 per cent. Unlike subjecs with iron deficiency in whom the mean corpuscular volume varied from 46 to 84, all individuals with beta-thalassermia trait exhibited microcytosis. In most instances, determination of FEP appears to distinguish beta-thalassemia trait from iron deficiency in patients with microcytosis.

Anemia, Hypochromic↗
PubMedDate not supplied

Aspects of in vitro placental perfusion: effects of hyperoxia and phenol red.

The study of a number of parameters of placental function indicated that the perfused human placental lobe maintained its structural and functional integrity when PO2 levels in buffer perfusate were near physiological values, despite low O2 consumption. High O2 content in the perfusate may reduce placental transfer either through a direct vasoconstrictor effect or in combination with the destruction of vascular cyclo-oxygenase, resulting in the reduced synthesis of the vasodilator prostacyclin. A similar mechanism may be involved in the reduction of placental transfer observed in the presence of phenol red. These studies suggest that aspects of in vitro methodologies which may relate to prostaglandin production deserve careful consideration and further study.

Antipyrine↗
PubMedDate not supplied

The effect of irradiation on platelet arachidonic acid metabolism.

Irradiation of platelets in vitro to 2000 rads did not alter arachidonic acid metabolism through the cyclooxygenase pathway. Production of platelet thromboxane B2 and 12-hydroxy-5,8-10-heptadecatrienoic acid remained similar in control and paired irradiated platelets. In paired samples the platelet lipoxygenase metabolite 12-hydroxy-5,8,10,14-eicosatetraenoic acid was significantly increased postirradiation to 42 +/- 2.8 percent when compared to a control value of 34.1 +/- 3.6 percent (p less than 0.02). Although this latter product has been demonstrated to be chemotactic for neutrophils, its role in platelet function has not been specifically determined.

12-Hydroxy-5,8,10,14-eicosatetraenoic Acid↗
PubMedDate not supplied

Isolated rupture of the patellar tendon in athletes.

The purpose of this study was to review patellar tendon ruptures in athletes treated with surgical repair. Six patellar tendon ruptures in five athletic patients were identified at our institution between 1980 and 1990. All patients had operative debridement and primary repair of the ruptured patellar tendon using nonabsorbable sutures passed through patellar drill holes at an average of 2.5 days after injury. Personal interview, physical examination, roentgenographic evaluation, and isokinetic strength testing were performed at an average of 6 years after surgery. At final followup, no patient had complaints referable to the patellar tendon repair; all were able to achieve their premorbid levels of sports at an average of 18 months after injury. No patient thought that the surgically repaired knee was unstable or activity-limiting. All patients demonstrated full range of motion and strength equal to or greater than that of the noninjured side. One patient required an arthroscopic lateral release for lateral patellar facet pressure syndrome with an excellent result. No complications occurred; no other reoperations were required. Complete disruption of the patellar tendon is an uncommon injury in athletic individuals without predisposing medical conditions. After acute operative repair and aggressive rehabilitation, an excellent and enduring functional outcome can be expected.

Adolescent↗
PubMedDate not supplied

Injuries in Junior A ice hockey. A three-year prospective study.

This 3-year prospective cohort observational analysis of elite amateur hockey players ranging in age from 17 to 20 years on a United States Hockey League team describes ice hockey injuries using a strict definition of injury, standardized reporting strategies, and diagnosis by a team physician. One hundred forty-two injuries were recorded for an on-ice injury rate of 9.4 per 1000 player hours. A player was 25 times more likely to be injured in a game (96.1 per 1000 player-game hours) than in practice (3.9 per 1000 player-practice hours). Game-related injuries were more frequent in the third period, and practice-related injuries occurred more often in the first third of the season. Collisions represented 51% of the total injuries. The most common types of injuries were strains, lacerations, contusions, and sprains. The face and the shoulder were most frequently injured. A facial laceration was the most common injury; acromioclavicular joint sprain was the second most common injury. Facial lacerations typically occurred in games and were stick related. Further research is necessary to determine if injuries in Junior A amateur ice hockey can be reduced by mandatory full facial protection, enforcement of existing rules, improvement in shoulder pad design, and by focusing more attention on stretching programs.

Adolescent↗
PubMedDate not supplied

Comparison of intersegmental tibiofemoral joint forces and muscle activity during various closed kinetic chain exercises.

The purpose of this study was to analyze intersegmental forces at the tibiofemoral joint and muscle activity during three commonly prescribed closed kinetic chain exercises: the power squat, the front squat, and the lunge. Subjects with anterior cruciate ligament-intact knees performed repetitions of each of the three exercises using a 223-N (50-pound) barbell. The results showed that the mean tibiofemoral shear force was posterior (tibial force on femur) throughout the cycle of all three exercises. The magnitude of the posterior shear forces increased with knee flexion during the descent phase of each exercise. Joint compression forces remained constant throughout the descent and ascent phases of the power squat and the front squat. A net offset in extension for the moment about the knee was present for all three exercises. Increased quadriceps muscle activity and the decreased hamstring muscle activity are required to perform the lunge as compared with the power squat and the front squat. A posterior tibiofemoral shear force throughout the entire cycle of all three exercises in these subjects with anterior cruciate ligament-intact knees indicates that the potential loading on the injured or reconstructed anterior cruciate ligament is not significant. The magnitude of the posterior tibiofemoral shear force is not likely to be detrimental to the injured or reconstructed posterior cruciate ligament. These conclusions assume that the resultant anteroposterior shear force corresponds to the anterior and posterior cruciate ligament forces.

Adult↗
PubMedDate not supplied

Predictors of injury in ice hockey players. A multivariate, multidisciplinary approach.

Eighty-six male high school ice hockey players participated in this prospective study to determine both the incidence of injury in high school ice hockey and the influence of physical, situational, and psychosocial factors. Physical factors included height, weight, vision, previous injuries, musculoskeletal abnormalities, and injuries present at the time of screening evaluations. Situational factors examined were level of participation, playing time, player position, and games versus practices. Psychosocial factors such as confidence, stress, social support, positive states of mind, and mood states were also examined to determine their influences on injury. Twenty-seven injuries occurred during the 1994 to 1995 season. As hypothesized, the overall incidence of injury in high school hockey games (34.4 per 1000 player-game hours) was less than the incidence of injury in Junior A hockey (96.1 per 1000 player-game hours) and was more than previously reported for Bantam youth hockey (10.9 per 1000 player-game hours). Injuries occurred more often in games than in practices, usually as a result of collisions. Physical factors such as player position and previous injuries did not significantly predict injuries, but players in the high playing time group were more likely to be injured. Psychosocial factors of low vigor and high fatigue as measured by the Incredibly Short Profile of Mood States (ISPOMS) significantly predicted high school ice hockey injuries.

Adolescent↗