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Biomedical subjects

J C Cool

Publications and source records attributed to J C Cool.

18 recordsLinked to original sources
PubMed1999

A biomechanical analysis of the vertebral and rib deformities in structural scoliosis.

Although the structural changes occurring in the scoliotic spine have been reported as early as the 19th century, the descriptions and biomechanical explanations have not always been complete and consistent. In this study, three-dimensionally rendered CT images of two human skeletons with a scoliotic deformity and two patients with serious scoliosis were used to describe the intrinsic vertebral and rib deformities. The pattern of structural deformities was found to be consistent. Apart from the wedge deformation of the apical vertebrae, a rotation deformity was found in the transversal plane between the vertebral body and the posterior complex: the vertebral body was maximally rotated towards the convexity of the scoliotic curve, whereas the tip of the spinous process was pointed to posterior. The rib deformities at the convex side of the scoliotic curve showed an increased angulation of the rib at the posterior angle, whereas the rib curve on the concave side was flattened. The observed vertebral deformities suggest that these are caused by bone remodelling processes due to forces in the anterior spinal column, which drive the apical vertebral body out of the midline, whereas forces of the musculo-ligamentous structures at the posterior side of the spinal column attempt to minimize the deviations and rotations of the vertebrae. The demonstrated rib deformities suggest an adaptation to forces imposed by the scoliotic spine.

Biomechanical Phenomena↗
PubMed1999

Temporal changes in TFF3 expression and jejunal morphology during methotrexate-induced damage and repair.

Trefoil factor TFF3 has been implicated in intestinal protection and repair. This study investigated the spatiotemporal relationship between TFF3 expression and morphological changes during intestinal damage and repair in a rat model of methotrexate-induced small intestinal mucositis. Intestinal tissues from rats with mucositis were collected daily for 10 days. Mucosal damage was characterized by an initial decrease in cell proliferation resulting in crypt loss, villus atrophy, and depletion of goblet cells, followed by hyperproliferation that lead to crypt and villus regeneration and mucous cell repopulation. TFF3 mRNA levels increased marginally during histological damage, and the cell population expressing TFF3 mRNA expanded from the usual goblet cells to include some nongoblet epithelial cells before goblet cell repopulation. TFF3 peptide, however, was depleted during histological damage and normalized during repair, mirroring the disappearance and repopulation of goblet cells. Although there is no temporal relationship between TFF3 levels and crypt hyperproliferation, confirming the nonmitogenic nature of TFF3, the coincidental normalization of TFF3 peptide with repopulation of goblet cells and mucin production after proliferative overshoot suggests that TFF3 may play a role in the remodeling phase of repair.

Animals↗
PubMed1998

Effect of antenatal tracheal occlusion on lung development in the sheep model of congenital diaphragmatic hernia: a morphometric analysis of pulmonary structure and maturity.

The incidence of congenital diaphragmatic hernia (CDH) is 1:1,207-5,000, and the condition is associated with high mortality and morbidity, attributed principally to associated pulmonary hypoplasia. Repairing the diaphragmatic defect by antenatal surgery has high mortality, mainly due to premature labor. Antenatal tracheal occlusion, which is achievable by less invasive methods, stimulates lung growth (weight and DNA). However, its effectiveness in reversing structural and maturational abnormalities and its optimal timing requires further investigation. We hypothesized that (1) antenatal tracheal occlusion performed in the lamb model of congenital diaphragmatic hernia will stimulate lung growth and structural development and restore lung structure and maturity toward normal levels by term gestation; (2) effects will be detectable by morphometric measurements of the following parameters: lung volume, ratio of parenchyma to nonparenchyma, volume density of connective tissue within nonparenchyma, ratio of gas exchange tissue to airspace in parenchyma, gas exchange surface area, capillary loading, alveolar/airspace density and alveolar perimeter; (3) effects will be seen in all lobes of the lung; and (4) a greater effect will be observed when tracheal occlusion is performed early rather than late in gestation. Fourteen lambs underwent CDH creation at gestation day 72-74 followed by tracheal occlusion at day 101 (n = 7) or 129 (n = 7). They were delivered by Cesarean section at 143 days (term = 145-149). Lungs were obtained at autopsy, inflation fixed, divided into lobes, and sampled; morphometric analysis was performed. Comparisons were made with previously reported results from control lungs of normal lambs and lambs with untreated CDH. In comparison with untreated lungs, antenatal tracheal occlusion at both times resulted in increased volumes for total lung and lobes, increased volume density of parenchyma and of airspace within parenchyma, and increased gas exchange surface areas. Normal values for gas exchange surface area density, and alveolar density and perimeter were attained and the lungs appeared more mature than non-occluded lungs. Tracheal occlusion earlier in gestation produced a greater effect, achieving greater than normal values for lung volumes and volume densities, whereas the capillary loading value was similar to normal lung. Later occlusion achieved less than normal values for lung volumes and volume densities, with a reduced capillary loading value. We conclude that antenatal tracheal occlusion is capable of reversing structural total lung and lobar hypoplasia and immaturity caused by CDH as determined by morphometrically determined parameters. The effect is greater when tracheal occlusion is performed early rather than late in gestation. The results are encouraging for development of treatment methods for humans with antenatally diagnosed CDH.

Animals↗
PubMed1998

Insulin-like growth factor-I (IGF-I) stimulates regrowth of the damaged intestine in rats, when administered following, but not concurrent with, methotrexate.

BACKGROUND: We tested the ability of insulin-like growth factor-I (IGF-I) to reduce damage to the intestinal mucosa (mucositis) in rats injected with methotrexate. IGF-I was infused concurrent with methotrexate administration and compared to IGF-I administered following the withdrawal of methotrexate. METHODS: Rats were injected with methotrexate at the start of days 1, 2 and 3. IGF-I was infused for 5 days, commencing at the start of day 1 [concurrent administration] or at the start of day 4 [post-methotrexate administration]. RESULTS: IGF-I administered coincident with methotrexate failed to restore mucosal integrity to the damaged small intestine. IGF-I administered post methotrexate stimulated regrowth of the damaged intestine, particularly the ileum, with 22%, 32% and 29% increases in small intestinal weight, ileal villus height and ileal crypt depth respectively. CONCLUSIONS: Following intestinal damage of methotrexate, IGF-I primarily induced growth of the distal small intestine. The ineffectiveness of concurrently administered IGF-I may have represented an IGF-I induced recruitment of proliferating epithelial cells to the anti-proliferative effects of methotrexate.

Animals↗
PubMed1998

Methods for reducing energy dissipation in cosmetic gloves.

For cosmetic reasons, hand prostheses are provided with cosmetic gloves. Their pleasing appearance, however, is accompanied by poor mechanical behavior, resulting in a negative influence on prosthesis operation. Glove stiffness is high and nonlinear, and internal friction in the glove material causes energy dissipation (hysteresis). In this article, two methods for reducing hysteresis in cosmetic gloves are proposed, that may be applied independently or in combination. Glove modification. Altering the mechanical properties of the glove itself is the first method that is presented. It was found possible to reduce both stiffness and hysteresis about 50% by forming grooves into the inside of the glove. Together with the evaluation of this method, several properties of the cosmetic glove were determined. Motion optimization. Additionally, a second method for reducing hysteresis was developed. The amount of hysteresis is influenced by the way the glove is forced to deform. The prosthesis mechanism, determining this deformation, was designed for minimum hysteresis and maximum cosmesis. For the prosthesis-glove combination used in this study, thumb motion optimization reduced hysteresis by about 65%.

Artificial Limbs↗
PubMed1996

Milk growth factors enriched from cheese whey ameliorate intestinal damage by methotrexate when administered orally to rats.

Currently, there are no truly effective therapies for the treatment of chemotherapy-induced intestinal mucositis, a debilitating side effect with a pathophysiology common to many chemotherapy regimens. We tested the efficacy of a growth factor extract derived from cheese whey against experimental intestinal mucositis in rats. Rats were subcutaneously injected with the chemotherapeutic drug methotrexate on d 1, 2 and 3 to induce severe damage in the small bowel and bacterial translocation across the gut. Whey extract (15 to 514 mg/d) was given orally for 5-12 d, starting on d 1. Controls were fed an isonitrogenous diet. Histological indices of villus and crypt integrity were utilized to assess potential efficacy of the extract. Administration of the whey extract for 5 d increased the villus surface length indices in the jejunum and ileum by 52% and 56%, respectively (P< 0.001) compared with controls not receiving the whey extract. The crypt area index was 64% greater (P < 0.001) in the jejunum, but not significantly greater in the duodenum or ileum compared with controls not receiving whey extract. Similarly, sucrase activity was significantly higher in the ileum (P < 0.001) but not significantly elevated in the jejunum, whereas bacterial translocation (incidence and number of colonies) was significantly reduced compared with controls not receiving whey extract. We conclude that oral whey growth factor extract reduces methotrexate-induced damage in the small bowel, which suggests clinical applications for the treatment of intestinal mucositis.

Administration, Oral↗
PubMed1994

Fetal lung compliance in premature and term lambs after two methods of in utero repair of diaphragmatic hernia.

BACKGROUND: In utero surgery was used to correct a surgically induced model of congenital diaphragmatic hernia (CDH) in premature and term lambs, resulting in an improvement in lung mechanics at birth. METHODS: The differences between the in utero "patch" repair method and the "silo" repair method were assessed in 55 lambs by measuring the static respiratory system compliance (CST,RS) at birth in term (approximately 145 day) and in premature (128 day) animals. RESULTS: Both methods resulted in similar improvements in CST,RS in term lambs, but in premature lambs only the silo method produced an increase in compliance. Comparisons of specific compliance related to length or birth weight did not alter these findings; however, corrections related to lung weight or a measure of lung volume showed there was no difference between any experimental groups in either term or premature lambs. CONCLUSIONS: These findings suggest that there was no difference in the intrinsic compliance of the lung tissue between normal, unrepaired and repaired animals, and that the differences in respiratory system compliance measured at birth may be due primarily to differences in lung size. The silo repair method appears to provide an earlier improvement in CST,RS than the patch repair method.

Animals↗
PubMed1993

Altered intestinal development after jejunal ligation in fetal sheep.

Experimental obstruction of the fetal small intestine resulted in massive hypertrophy of the segment proximal to the site of obstruction. Villus morphology was grossly abnormal. Enterocytes developed many irregular features, most notably cytoplasmic extensions (pseudopods, or blebs) from their apical surface. Distal to the site of obstruction, morphological anomalies which resembled those seen after experimental oesophageal ligation were found. These included delayed disappearance of the apical endocytic network, disrupted or absent microvilli, glycogen accumulation and inappropriate cell extrusion. Proximal to the obstruction, where stasis of swallowed fluid occurs, distension and abnormal intestinal development ensues. Distal to the obstruction where the intestine develops in the absence of swallowed fluid, development is also abnormal. The anomalies resemble those noted after oesophageal ligation in utero, and possibly are the results of reduced cellular nutrition. These results suggest that fetal ingestion provides the developing gastrointestinal tract with an important stimulus for normal growth.

Animals↗
PubMed1993

Intrathoracic silo for fetal diaphragmatic hernia: lung growth and slow reduction of abdominal viscera.

Correction of a left congenital diaphragmatic hernia in a human fetus with a large volume of liver in the chest requires reduction of liver and viscera into the abdomen. This can kink the ductus venosus and cause the death of the fetus. Therefore, we have repaired surgically created diaphragmatic hernias in fetal lambs by leaving viscera in the chest wrapped in a silastic chimney. With fetal growth there is a relative reduction of hernia volume over weeks, potentially avoiding kinking the ductus venosus. In four groups of lambs lung size and static respiratory system compliance at birth were compared. Lambs treated by this new technique (silo, n = 7) were compared with lambs that had undergone immediate complete correction with a flat silastic patch in the diaphragm plus an abdominal patch (patch, n = 8), with lambs with uncorrected hernias (n = 6), and with normals (n = 8). There was no significant difference between total lung weights (131 +/- 6 g v 157 +/- 13 g, mean +/- SEM, silo v patch) and lung displacement volumes (142 +/- 7 mL v 162 +/- 14 mL) in either surgically corrected group. Lungs from those corrected by silo were significantly heavier than those with uncorrected herniae (131 +/- 6 g v 56 +/- 5 g, P < .01), but were not as heavy as normal lungs (131 +/- 6 g v 257 +/- 16 g, P < .01).(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1989

Biomechanics of orthoses for the subluxed shoulder.

Based on biomechanics several operational principles for the neutralization of a shoulder subluxation are described. The pros and cons of the operational principles are discussed. A detailed analysis of the forces acting on the upper and lower arm indicates a preference for only one of the operational principles and explains why the arm sling and hemisling fail in the elimination of subluxation. With the operational principle selected a shoulder orthosis has been developed. Clinical results are given.

Biomechanical Phenomena↗
PubMed1976

An elbow orthosis.

An elbow orthosis for unilaterally handicapped persons has been developed. The operating principles and construction of the orthosis are described and its important parameters are determined. The procedure of parameter adjustment is given in detail and the area of application is indicated. Preliminary clinical results are discussed.

Elbow↗
PubMedDate not supplied

Glycine as a potential window for minimal access fetal surgery.

Carbon dioxide insufflation of the uterine cavity in sheep enables electrocautery to the surface and superficial tissues of the fetal lamb, using minimally invasive surgery. Absorption of the CO2, however, causes a potentially lethal acidosis. To enable the use of electrocautery dissection of the fetal sheep, without using gas, we have partially replaced the amniotic fluid with 0.5% glycine. To determine whether glycine would have any short- or long-term deleterious effects on the developing fetus, we replaced amniotic fluid with 0.5% glycine in 10 normal fetuses at 101 days of gestation (normal gestation 145-149 days), without later replacing it with the removed amniotic fluid. Histological changes were then sought in the skin, gastrointestinal tract, and pulmonary tree, at 2 ('early', n = 5) or 6 weeks ('late', n = 5) after the introduction of the glycine. There were no histological differences between these and normal sheep at either time point. The use of glycine as a replacement for amniotic fluid subsequently enabled us to carry out electrocautery dissection of the sheep fetus and electrocoagulation of any bleeding vessel. Its use was not associated with any apparent untoward effects. Therefore, it has the potential to be used in minimally invasive surgery on the fetal trachea or on an enlarged fetal bladder.

Amniotic Fluid↗
PubMedDate not supplied

Body-powered hand prosthesis with low operating power for children.

For unilateral below-elbow amputated children a new elbow-controlled hand prosthesis has been developed. Since the triceps of young children have insufficient power to activate normal spring-closing hands, a special mechanism with low operating power has been developed for this prosthesis. A stiff spring gives a good gripping force. When the elbow is slightly extended this spring is switched off, and by further extension the hand is opened against a weak spring. So far, six children have used this special prosthesis. Their initial enthusiasm resulted in an improved system, which is now being designed.

Artificial Limbs↗
PubMedDate not supplied

Morphometric analysis of pulmonary development in the sheep following creation of fetal diaphragmatic hernia.

Congenital diaphragmatic hernia (CDH) in humans is relatively common and associated with high mortality attributed mainly to pulmonary hypoplasia. Previous animal models have induced CDH late in gestation, in contrast to the human situation, and only limited morphometric analyses have been reported. We undertook early surgical creation of CDH in fetal lambs, days 72-74 of gestation (n = 8), with unoperated lambs (n = 8) as controls. At 143 days (term = 145-149) a cesarean section was performed and the lungs were obtained, inflation fixed, divided into lobes, and processed for morphometry. In the CDH group the total lung volumes (51.3 mL compared to 223.8 mL) and gas exchange surface areas (5.85 m2 versus 26.43 m2) were less than one quarter of control values. Capillary loading was reduced from 0.3 mL/m2 in controls to 0.12 mL/m2 in CDH and parenchymal volume reduced from 77% in controls to 57% in CDH. Within parenchyma, gas exchange tissue volume was increased in CDH (66%) compared with controls (50%). CDH lungs had primitive air sacs/alveoli that were smaller (perimeter 83 microns) and more numerous (1321 per mm2) than in controls (perimeter 132 microns, 504 per mm2). The left lung and left upper lobe were affected most. Induction of CDH in the lamb at this early age results in quantifiable, reproducible pulmonary hypoplasia from which comparisons can be made with the human condition.

Animals↗