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Biomedical subjects

R C Cohen

Publications and source records attributed to R C Cohen.

31 records · Page 2Linked to original sources
PubMed1992

Volume expanded diuretic renography in the postnatal assessment of suspected uretero-pelvic junction obstruction.

Controversy surrounds the role of 99mTc-diethylenetriamine pentaacetic acid renography in suspected uretero-pelvic junction obstruction in early life. Accordingly, we retrospectively reviewed 18 patients (28 hydronephrotic kidneys) with a mean age of 2 mo (range: 1 wk-6 mo) who underwent a total of 36 scans using intravenous volume expansion (10 ml/kg) and furosemide diuresis (1 mg/kg). Initial scans were classified as obstructed, not obstructed or indeterminate using differential renal function, furosemide washout T 1/2 and visual assessment of tracer clearance. Those initially classified as obstructed (n = 8) have been surgically confirmed. In the indeterminate (n = 6) and nonobstructed (n = 14) groups, three and two kidneys, respectively, developed obstruction on progress scans. Mean follow-up in the nonsurgical patients was approximately 9 mo (range: 4-17 mo). A total of 13 kidneys had developed obstruction by renographic criteria, and to date 12 have surgical confirmation. Our data indicate that: (1) scans classified as obstructed correlate well with surgery; (2) an initial classification of indeterminate or nonobstructed does not exclude later development of obstruction; and (3) serial scans correctly stratify children with possible uretero-pelvic junction obstruction.

Female↗
PubMed1990

Tunable far-IR laser spectroscopy of jet-cooled carbon clusters: the nu 2 bending vibration of C3.

Seven rovibrational transitions of the (01(1)0) <-- (00(0)0) fundamental bending band of C3 have been measured with high precision with the use of a tunable far-infrared laser spectrometer. The C3 molecules were produced by laser vaporization of a graphite rod and cooled in a supersonic expansion. The astrophysically important nu 2 fundamental frequency is determined to be 63.416529(40) cm-1. These measurements provide the basis for studies of C3 in the interstellar medium with far-infrared astronomy.

Astronomy↗
PubMed1990

Diagnosis and treatment of antenatal uropathies.

Thirty-five patients with significant fetal hydronephrosis detected on antenatal ultrasound had postnatal investigations which included ultrasound, 99mtechnetium diethylenetriamine pentacetic acid (99mTcDTPA) renal scans and micturating cystourethrograms. Antenatal and postnatal ultrasound were unable to determine reliably the level of obstruction causing the hydronephrosis. The 99mTcDTPA renal scan was useful in determining the necessity and timing of surgery, but could not exclude vesico-ureteric reflux. Seven patients required surgery in the neonatal period and a further seven children had surgery because of deterioration of the scan appearance on follow-up studies performed at 3, 6 and 12 months of age and then at longer time intervals. Twenty patients (almost 60%) have been managed conservatively for a mean of 28 months (range: 12 months-7 years) with no deterioration in renal function.

Female↗
PubMed1987

Traumatic oesophageal pseudodiverticulum.

Dissection of the posterior pharyngeal wall and oesophagus due to trauma has a clinical presentation similar to that of oesophageal atresia with or without tracheo-oesophageal fistula. It is important to establish the diagnosis in order to prevent unnecessary surgery.

Diagnosis, Differential↗
PubMed1986

Diagnosis and management of massive hepatic hemangiomas in childhood.

Twelve patients diagnosed as having hepatic hemangiomas during 1960 to 1982 at the Royal Children's Hospital, Melbourne are reviewed. This rare benign vascular tumor can present considerable problems in both diagnosis and management and has a high reported mortality. Our experience over this 23-year period demonstrates some of the difficulties in diagnosis and suggests a plan of management. Eight patients were diagnosed when five weeks of age or less, the youngest was 24 hours old. One was diagnosed at four months of age. In the remaining three patients, the diagnosis was made at postmortem. Ten patients had prominent hepatomegaly, nine had congestive cardiac failure and in one of these the onset was delayed four weeks. Thrombocytopenia was present in five and jaundice in four patients. Four patients had associated cutaneous or visceral hemangiomas. Seven patients underwent selective hepatic arteriography, and two of these had prior ultrasound examinations of the liver. Management of congestive cardiac failure included steroids, radiotherapy, hepatic resection, and in one patient, hepatic artery ligation. One patient with diffuse hepatic hemangiomas did not require any specific therapy and resolved spontaneously over two years. The four patients in whom hepatic resection was performed survived.

Angiography↗
PubMed1986

A new model of tracheal stenosis and its repair with free periosteal grafts.

Stenosis of 50% to 80% of the cervical or thoracic tracheal lumen was created in 17 piglets by encircling the trachea with silicone rubber sheet for 3 to 19 days (median 14 days). In 13 animals thoracic tracheal stenosis was repaired by longitudinal incision and insertion of a free tibial periosteal graft into the defect. An omental pedicle graft was applied to the surface of the free periosteal graft to augment its blood supply in three of these animals. An endotracheal silicone rubber splint was left in place for 2 to 3 weeks after the operations. Four animals served as untreated controls. In 12 of 13 piglets respiratory obstruction was relieved. One repair failed because of graft necrosis. In two animals put to death 1 month and 2 months later, stenosis was absent and the grafts showed variable ossification. The luminal surface had epithelialized. In nine of 10 animals put to death 3 months after the operation, tracheal cross-sectional areas had doubled, stenosis and granulation tissue were absent, and all the grafts had ossified and epithelialized. A mild stenosis (24%) developed over a 2 mm length in one animal and the graft had not ossified. The omental pedicle graft did not improve vascularization of the free periosteal graft. These studies describe a model of tracheal stenosis that can be used to assess various methods of repair. The results indicate that tracheal stenosis can be successfully treated by incision and insertion of a free periosteal graft into the defect.

Animals↗
PubMed1985

The successful reconstruction of thoracic tracheal defects with free periosteal grafts.

A defect was created in the thoracic trachea in nine piglets (10 kg) by excising a segment from the entire thoracic trachea proximal to the right upper lobe bronchus (3 to 3.5 cm in length) and 30% of the circumference in width (1 to 1.5 cm). The defect was repaired with a free tibial periosteal graft (FPG) and in four piglets an omental pedicle graft (OPG) was applied to the surface of the FPG. An internal tracheal splint was inserted for 12 to 16 days to support the repair and prevent air leak. The splints were removed bronchoscopically. None of the pigs developed signs of airway obstruction at any stage following the repair. Eight were killed 3 months postoperatively when four to six times their original weight. One pig died on the 18th postoperative day of unknown cause. The tracheas were removed, x-rayed, and examined grossly and histologically. The results demonstrated normal tracheal growth with absence of either stenosis, collapse, or granulation tissue. All grafts were viable, bone formation was present, and the lumenal surfaces were lined with columnar and respiratory epithelium. The OPG did not improve vascularization of the FPG. This model suggests that tracheal stenosis in children may be surgically corrected by simply incising the stenotic segment longitudinally and enlarging the tracheal diameter by inserting a FPG into the defect.

Animals↗
PubMed1984

Alterations in immunoglobulin synthesis by peripheral blood mononuclear cells from splenectomized patients with and without splenic regrowth.

Unstimulated and pokeweed mitogen (PWM)-stimulated immunoglobulin (Ig) synthesis by peripheral blood mononuclear cells (PBMC) in vitro, serum Ig concentrations, and the degree of splenic regrowth was studied in 33 patients who had been splenectomized following trauma. The concentration of IgG and IgA was significantly raised in the supernatants of unstimulated cultures of PBMC from the patients. The stimulation of Ig synthesis by PWM, measured as a stimulation index (SI), was significantly less in the culture of PBMC from the patients, compared with the controls. The SI was reduced both in those patients whose unstimulated PBMC secreted normal concentrations of IgG and IgA in culture, as well as in those whose cells secreted elevated concentrations of Ig. The concentration of IgM in the serum of the patients was significantly reduced compared with the controls, the serum IgG was raised, and the serum IgA was not altered. The degree of splenic regrowth (splenosis) was measured in the patients by splenic scanning, by using heat-damaged, radiolabeled autologous erythrocytes. The patients were allocated into four groups, depending on whether they had no (11 patients), minimal (11), moderate (seven), or large (four) splenosis. There was no difference between any of the groups with respect to the synthesis of IgG or IgA in culture or the serum Ig concentrations. These results indicate that Ig synthesis by PBMC in vitro, and serum Ig concentrations in vivo, are abnormal in patients who have been splenectomized for trauma, and that the generation of splenosis tissue does not correct these changes.

Adolescent↗
PubMed1982

Immune dysfunction in the presence of residual splenic tissue.

Immunological function was examined in children who had undergone splenectomy, in 8 for trauma, and in 11 for haematologic/oncologic reasons. Particular emphasis was placed on the effects of residual splenic tissue on immune function. Children in the elective group had no evidence of splenosis but 6 of the 8 trauma patients showed residual splenic activity. A general trend indicated that immunological dysfunction was associated with the presence of residual splenic tissue. Three patients with significant post-traumatic splenosis showed low IgM levels, one also had a low IgG level and another a low IgA and impaired lymphocyte response to mitogens. The trauma patients with little or no splenic tissue had normal immune functions. Immunological abnormalities were found in 8 of the 11 haematologic/oncologic patients with no splenosis suggesting the abnormalities were possibly due to the primary disease. In contrast to the popular belief that splenosis confers protection against overwhelming sepsis, the present findings suggest that patients with residual splenic tissue are at a greater risk of infection because of a lower level of immune response.

Adolescent↗