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Biomedical subjects

R W Walker

Publications and source records attributed to R W Walker.

At least 37 records · Page 2Linked to original sources
PubMed1997

Blood loss during primary total hip arthroplasty: use of preoperative measurements to predict the need for transfusion.

The blood loss resulting from total hip arthroplasty was studied in 53 patients. Calculated blood loss exceeded measured blood loss in all cases. The most significant predictor of postoperative packed-cell volume (PCV) was the preoperative PCV. In a further 37 patients the preoperative PCV was used successfully to predict the postoperative PCV and the need for transfusion.

Arthroplasty, Replacement, Hip↗
PubMed1996

Quantity and distribution of Malassezia organisms on the skin of clinically normal dogs.

OBJECTIVE: To define the extent to which Malassezia organisms can be recovered from the skin of clinically normal dogs and to assess differences in organism recovery related to anatomic sampling site and to method of collection. DESIGN: Prospective, controlled study. ANIMALS: 19 clinically normal dogs. PROCEDURE: The number of Malassezia pachydermatis organisms were determined in fungal cultures of samples obtained from the skin of clinically normal dogs, using an adhesive tape method to obtain samples from 10 sites/dog. Additionally, 3 methods (direct impression, swabbing technique, and superficial skin scraping) that are commonly used for obtaining samples for cytologic examination were evaluated. RESULTS: Malassezia organisms were found in low numbers as part of the microflora of the skin of clinically normal dogs. Number of organisms differed significantly for various anatomic locations (chin, highest number; inguinal and axillary regions, lowest number). Malassezia organisms were identified more frequently by use of adhesive tape and fungal culturing than by the methods used for cytologic examination. However, comparing methods used for obtaining samples for cytologic examination with each other, marked differences were not detected in our ability to recover yeast organisms among the 3 techniques. CLINICAL IMPLICATIONS: Although Malassezia spp is part of the microflora of the skin of clinically normal dogs, it is extremely difficult to detect the organism by any of the 3 sampling methods used for sample collection for cytologic examination. Therefore, anatomic site and method of sample collection should be considered when attempting to make a diagnosis of Malassezia dermatitis.

Animals↗
PubMed1996

Anaesthesia for Rett syndrome.

Rett syndrome is a devastatingly disabling neurological disease that is only observed in girls. Scoliosis occurs in roughly half the girls and surgery may be required. Anaesthesia is described in three patients. Sudden death may be a feature of the disease which occurred four weeks postoperatively in one case. Although a long QTc interval may be seen, it did not occur in any of our cases.

Adolescent↗
PubMed1996

Chemotherapy without irradiation--a novel approach for newly diagnosed CNS germ cell tumors: results of an international cooperative trial. The First International Central Nervous System Germ Cell Tumor Study.

PURPOSE: Radiation therapy for CNS germ cell tumors (GCT) is commonly associated with neurologic sequelae. We designed a therapeutic trial to determine whether irradiation could be avoided. PATIENTS AND METHODS: Patients received four cycles of carboplatin, etoposide, and bleomycin. Those with a complete response (CR) received two further cycles; others received two cycles intensified by cyclophosphamide. RESULTS: Seventy-one patients were enrolled (45 with germinoma and 26 with nongerminomatous GCT [NGGCT]). Sixty-eight were assessable for response. Thirty-nine of 68 (57%) achieved a CR within four cycles. Of 29 patients with less than a CR, 16 achieved CR with intensified chemotherapy or second surgery. Overall, 55 of 71 (78%) achieved a CR without irradiation. The CR rate was 84% for germinomas and 78% for NGGCT. With a median follow-up duration of 31 months, 28 of 71 patients were alive without relapse or progression. Thirty-five showed tumor recurrence (n = 28) or progression (n = 7) at a median of 13 months. Twenty-six of 28 patients (93%) who recurred following remission underwent successful salvage therapy. Pathology was the only variable predictive of survival. The probability of surviving 2 years was .84 for germinoma patients and .62 for NGGCT. Seven of 71 patients died of toxicity associated with study chemotherapy. CONCLUSION: Forty-one percent of surviving patients and 50% of all patients were treated successfully with chemotherapy only without irradiation. Chemotherapy-only regimens for CNS GCT, although encouraging, should continue to be used only in the setting of formal clinical trials.

Adolescent↗
PubMed1995

A clinical and molecular genetic study of dentatorubropallidoluysian atrophy in four European families.

Dentatorubropallidoluysian atrophy is a neurodegenerative disorder with characteristic pathology, chiefly described in reports from Japan, and is associated with an unstable CAG trinucleotide repeat in a gene on chromosome 12. We describe four European families, three British and one Maltese, with this mutation. All exhibited autosomal dominant inheritance, and there was evidence for anticipation associated with an increase of the expansion with paternal transmission in two families. Affected chromosomes from patients with dentatorubropallidoluysian atrophy had CAG expansions of 58 to 74 repeats, compared to 7 to 26 in control chromosomes, and the size of repeat was significantly inversely correlated with age of onset. The clinical features were diverse, even within individual families, and comprised a combination of a movement disorder (chorea, myoclonus, dystonia, or parkinsonism), cerebellar ataxia, epilepsy, psychosis, and dementia. A clinical diagnosis of Huntington's disease had been made in affected individuals from all families. Neuropathological examination of 2 patients showed no specific abnormality in one and degenerative changes predominantly affecting the spinal cord in the other. Investigation of 55 patients who might represent sporadic examples of dentatorubropallidoluysian atrophy did not detect any expanded alleles. Dentatorubropallidoluysian atrophy is likely to be more common than previously recognized in non-Japanese populations, and should be considered in any patient with a dominantly inherited neurodegenerative disorder with the above-mentioned clinical features.

Adolescent↗
PubMed1995

Adenocarcinomatous transformation of intracranial germ cell tumors.

Germ cell tumors arising in the gonads, retroperitoneum, and mediastinum are occasionally overgrown by cancers of somatic type that are widely assumed to derive from the "malignant transformation" of included teratomatous tissues. These malignant, nongerminal neoplasms are typically chemoresistant, and their emergence is often associated with fatal treatment failure. Only rare, well-documented reports of sarcomatous transformation complicating intracranial germ cell neoplasia are on record. We describe two nongerminomatous germ cell tumors of the pineal region that underwent transformation into enteric-type adenocarcinoma. Both recurred in a locally aggressive fashion, one proving rapidly fatal owing to the development of multiple cerebral and cerebellar metastases and spinal leptomeningeal adenocarcinomatosis.

Adenocarcinoma↗
PubMed1995

Medulloblastoma/primitive neuroectodermal tumor in 45 adults.

Medulloblastoma/primitive neuroectodermal tumor (PNET) is an uncommon tumor in adults. We reviewed the medical records of 45 patients, 15 years or older, with medulloblastoma/PNET. Most patients presented with symptoms referable to the posterior fossa, and 31 of 45 patients had disease limited to the posterior fossa at the time of diagnosis. Despite initial favorable response to surgical resection, radiation, and chemotherapy, one-half had recurrence 10 to 76 months after initial treatment. Only two of these patients had local recurrence; the remainder had CNS dissemination, systemic metastasis, or both. The recommended approach to medulloblastoma/PNET in adults is similar to that in children, and includes initial staging evaluation, systemic and focal therapy (ie, neuraxis irradiation with posterior fossa boost and chemotherapy), and long-term follow-up to detect late and distant recurrence.

Adolescent↗
PubMed1994

Anaesthesia and mucopolysaccharidoses. A review of airway problems in children.

The airway problems encountered during anaesthesia in all children with mucopolysaccharidoses presenting for a surgical procedure from 1988 to September 1991 are reviewed. Thirty-four patients underwent 89 anaesthetics for 110 procedures. The results reveal a high incidence of airway problems. The overall incidence of difficult intubation was 25% and failed intubation 8%. In those children with Hurler's syndrome, the difficult intubation incidence was 54% and failed intubation incidence 23%. Other potential anaesthetic problems such as cardiac anomalies and obstructive sleep apnoea are also reviewed.

Adolescent↗
PubMed1993

Effect of brain irradiation on demyelinating lesions.

Demyelinating lesions, such as those in multiple sclerosis, may resemble primary or metastatic brain tumors on CT or MRI, and even be mistaken for neoplasms on biopsy. We encountered five such patients in whom an incorrect diagnosis of CNS neoplasm was made on the basis of radiologic appearance (five) and biopsy (four). All five received radiation therapy, and three chemotherapy. Review of the pathologic findings indicated that the original lesions were not neoplastic but demyelinative. The four patients who received radiation in full tumoricidal doses had unexpectedly poor clinical outcome, suggesting that radiation is especially injurious to patients with demyelinating disease.

Adult↗
PubMed1992

Extraneural metastases of infratentorial glioblastoma multiforme to the peritoneal cavity.

This report describes two autopsy-proven cases of a rare complication of infratentorial glioblastoma multiforme (GBM): metastatic seeding of the peritoneal cavity through ventriculoperitoneal (VP) shunts. Patient 1 was a 13-year-old boy with a pontine GBM, and Patient 2 was a 9-year-old girl with a thoracolumbar spinal cord GBM. Autopsy of both patients demonstrated leptomeningeal gliomatosis encasing the spinal cord and basal structures of the brain, in addition to peritoneal and omental metastases. The pattern of abdominal metastasis seen in these patients is typical of tumors that directly seed the peritoneal cavity and implicates the VP shunt as the vehicle of extraneural spread. Although a rare occurrence, extraneural metastases should be sought in patients with glioma with VP shunts who demonstrate increased abdominal girth, unexplained weight gain, or persistent abdominal pain.

Adolescent↗
PubMed1992

Intra-arterial cisplatin--associated optic and otic toxicity.

Over a 22-month period, we investigated optic and otic toxicity accompanying intra-arterial cisplatin therapy. Baseline and serial neurologic and ophthalmologic examinations, visual evoked potentials, and brain-stem auditory evoked potentials were performed in six patients, aged 37 to 53 years. Patients received infraophthalmic intra-arterial cisplatin (60 mg/m2) every month for three to 10 treatments (mean, six treatments). Five of the six patients had progressive optic toxicity. In two patients, the visual evoked potential prolongation preceded acuity loss by at least 4 months. Two patients had evidence of otic toxicity by either brain-stem auditory evoked potential or click threshold and brain-stem auditory evoked potential. Intra-arterial cisplatin neurotoxicity may be significant in patients with already limited survival. Visual evoked potential and brain-stem auditory evoked potential should be used to monitor patients receiving potentially neurotoxic therapy.

Adult↗
PubMed1992

Extraneural metastases in ependymoma.

Ependymomas, glial neoplasms usually arising in the posterior fossa or spinal cord, rarely metastasize outside the central nervous system. We have reviewed all 81 ependymomas evaluated at MSKCC between 1956-1989. Five (6.2%) had extraneural metastases (ENM). The primary tumor was in spinal cord in 3 patients and the cerebral hemisphere in 2. Two tumors were histologically anaplastic; 3 were histologically benign. The 5 patients were 3, 3, 3.5, 16 and 37 years old. Time from initial diagnosis to development of ENM was 0, 15, 35, 40, and 288 months. At the time of ENM the primary tumor was progressing in 4/5 patients. Prior therapy had included resection plus radiation therapy (RT) (1), RT plus chemotherapy (1), resection plus RT plus chemotherapy (2). One patient had not received prior therapy because ENM were present at diagnosis. The sites of ENM included lung and thoracic lymph nodes (2), pleura and peritoneum (2), and liver (1). Both patients with peritoneal ENM had had ventriculoperitoneal shunts. ENM did not correlate with histologic grade, age, or degree of surgical resection. When patients with ependymoma develop signs or symptoms of systemic disease such as abdominal pain, cough, or adenopathy, ENM should be considered.

Adolescent↗