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P H Cogen

Publications and source records attributed to P H Cogen.

34 records · Page 2Linked to original sources
PubMed1992

Involvement of multiple chromosome 17p loci in medulloblastoma tumorigenesis.

Loss of heterozygosity for sequences located on chromosome 17p in several tumor types is often associated with mutations in the tumor suppressor gene p53. We previously showed consistent deletion of chromosome 17p12-13.1 in medulloblastoma, a common childhood brain tumor. Using denaturing gradient gel electrophoresis and direct sequencing, we have detected p53 mutations in only two of 20 medulloblastoma specimens. Moreover, additional RFLP studies of these 20 specimens showed loss of heterozygosity at a more distal and distinct site, 17p13.3. Deletion of 17p almost invariably signified a negative prognosis. Our results suggest that p53 mutations may contribute to the pathogenesis of medulloblastoma in relatively few cases. The consistent deletion of other discrete loci on 17p suggests that additional or alternative tumor suppressor genes may contribute to the tumor's phenotype.

Base Sequence↗
PubMed1991

Identification of a germ-line mutation in the p53 gene in a patient with an intracranial ependymoma.

We detected a germ-line mutation of the p53 gene in a patient with a malignant ependymoma of the posterior fossa. This mutation, which was found at codon 242, resulted in an amino acid substitution in a highly conserved site of exon 7 of the p53 gene; the same mutation was found in both the germ-line and the tumor tissue. This is the most common region of previously described somatic p53 mutations in tumor specimens and of the germ-line p53 mutations in patients with the Li-Fraumeni cancer syndrome. Evaluation of the patient's family revealed several direct maternal and paternal relatives who had died at a young age from different types of cancer. The association of a germ-line p53 mutation with an intracranial malignancy and a strong family history of cancer suggests that p53 gene mutations predispose a person to malignancy and, like retinoblastoma mutations, may be inherited.

Amino Acid Sequence↗
PubMed1991

Ultrasound-guided aspiration of a neonatal brain abscess.

The authors successfully treated a Serratia marcescens brain abscess in the right parieto-occipital region of a newborn infant born at 27 weeks' gestation and weighing 800 g. Bedside ultrasound-guided aspiration techniques and local anesthesia were used to treat the abscess.

Brain Abscess↗
PubMed1991

Loss of heterozygosity for chromosome 22 DNA sequences in human meningioma.

Monosomy of chromosome 22 in meningioma was the first consistent cytogenetic anomaly reported for a solid tumor. Although most meningiomas are isolated sporadic lesions, multiple and familial occurrences have been reported, usually in cases of documented neurofibromatosis 2 (NF2). Previous reports have placed the NF2 locus on chromosome 22, flanked by the markers D22S1 and D22S28. We report a restriction fragment-length polymorphism study of 16 meningiomas conducted using chromosome 22 probes. None of the patients had clinical findings or a family history of NF2, although two of them eventually developed multiple intracranial meningiomas. Detectable loss of chromosome 22 sequences was observed in 50% of informative patients. Deletion mapping of tumors with preserved sequences showed that the loss of chromosome 22 DNA overlapped the region previously linked to NF2, but also included a sequence distal to the NF2 locus. These results suggest that the oncogenesis of human meningioma involves inactivation of a chromosome 22 locus that may be in close proximity to the gene for NF2.

Blotting, Southern↗
PubMed1991

Intracranial arachnoid cysts in children. A comparison of the effects of fenestration and shunting.

The best operative intervention for children with arachnoid cysts remains the subject of controversy. Recent reports stress that craniotomy for cyst fenestration is associated with a low incidence of morbidity and mortality and may leave the child shunt-independent. The cases of 40 pediatric patients with arachnoid cysts treated between 1978 and 1989 are reported. Five children with mild symptoms and small cysts that remained stable on follow-up studies have not required surgical intervention. Of 15 patients with cysts initially treated by fenestration, 10 (67%) showed no clinical or radiographic improvement postoperatively and have undergone cyst-peritoneal (eight patients) or ventriculoperitoneal (VP) shunting (one patient), or revision of a VP shunt placed for hydrocephalus before cyst fenestration (one patient). Two other patients with existing VP shunts required no further procedures. Thus, only three (20%) of 15 patients initially treated by fenestration remain shunt-independent after a median follow-up period of 8 years. The 20 other patients were initially treated by cysts shunting and all improved postoperatively; shunt revision has been necessary in six (30%) of these 20 patients because of cysts recurrence. Cyst location influenced the success of shunt treatment; none of the seven middle cranial fossa cysts treated by shunting have required revision, but results with cysts in other locations were less favorable. In all locations, though, shunting was more successful than fenestration. It is concluded that cyst-peritoneal or cyst-VP shunting is the procedure of choice for arachnoid cysts in most locations, including those in the middle cranial fossa.

Arachnoid↗
PubMed1991

Medulloblastoma: freedom from relapse longer than 8 years--a therapeutic cure?

Seventy-seven patients presenting with medulloblastoma between 1958 and 1986 were treated at Stanford University Medical Center and studied retrospectively. Multimodality therapy utilized surgical extirpation followed by megavoltage irradiation. In 15 cases chemotherapy was used as adjunctive treatment. The 10- and 15-year actuarial survival rates were both 41% with an 18-year maximum follow-up period (median 4.75 years). There were no treatment failures after 8 years of tumor-free survival. Gross total removal of tumor was achieved in 22 patients (32%); the surgical mortality rate was 3.9%. No significant difference was noted in the incidence of metastatic disease between shunted and nonshunted patients. The classical form of medulloblastoma was present in 67% of cases while the desmoplastic subtype was found in 16%. Survival rates were best for patients presenting after 1970, for those with desmoplastic tumors, and for patients receiving high-dose irradiation (greater than or equal to 5000 cGy) to the posterior fossa. Although early data on freedom from relapse suggested a possible beneficial effect from chemotherapy, long-term follow-up results showed no advantage from this modality of treatment. The patterns of relapse and survival were examined; 64% of relapses occurred within the central nervous system, and Collins' rule was applicable in 83% of cases beyond the period of risk. Although patients treated for recurrent disease could be palliated, none were long-term survivors. The study data indicate that freedom from relapse beyond 8 years from diagnosis can be considered as a cure in this disease. Long-term follow-up monitoring is essential to determine efficacy of treatment and to assess survival patterns accurately.

Actuarial Analysis↗
PubMed1991

Metastatic juvenile pilocytic astrocytoma. Case report.

The authors report the case of a metastatic juvenile pilocytic astrocytoma of the hypothalamic region in a 10-year-old boy. Eight years after craniotomy and radiation therapy, the tumor spread via cerebrospinal fluid pathways to the left cerebellar tonsil and the lumbosacral region. Histological evaluation of both the original hypothalamic and the new lumbosacral masses showed features of a slow-growing juvenile pilocytic astrocytoma with no evidence of malignant transformation. The clinical implications and possible mechanisms of metastatic spread are discussed.

Astrocytoma↗
PubMed1990

Deletion mapping of the medulloblastoma locus on chromosome 17p.

Isochromosome 17q has previously been observed consistently in cytogenetic studies of medulloblastoma, the most common posterior fossa neoplasm in children. We performed a restriction fragment length polymorphism (RFLP) investigation of medulloblastoma which showed a loss of chromosome 17p sequences in 45% of these tumors. This finding was predictive of a poor clinical response to treatment. A contiguous panel of markers permitted mapping of the deletion to 17p12-p13.1, the same chromosomal region for which loss of alleles has been shown in tumor specimens from patients with colon cancer, and the same region to which the p53 gene has been mapped. This suggests that medulloblastoma is associated with a recessive oncogene on chromosome 17p that may be involved in the genesis of several embryologically unrelated neoplasms and that the absence of this gene in tumor tissue has prognostic significance.

Brain Neoplasms↗
PubMed1990

Bladder function in patients with lipomyelomeningocele.

We evaluated preoperative and postoperative bladder function in 31 consecutive patients who underwent definitive operative correction of lipomyelomeningocele. Of 12 patients less than 1.5 years old at operation, bladder function was normal preoperatively and postoperatively in 5 (42%) and normalized postoperatively in 4 (33%). In 5 patients (42%) abnormal urodynamic findings were the only sign of neurological abnormality. Of the 19 patients older than 1.5 years at operation bladder function was normal preoperatively and postoperatively in only 4 (21%), and normalized postoperatively in none. We conclude that the majority of patients with lipomyelomeningocele have bladder dysfunction, and that in some cases this dysfunction can be prevented and/or reversed by early neurosurgical intervention. Urodynamic assessment is helpful as part of the neurological evaluation and in directing patient care.

Adolescent↗
PubMed1990

Intracerebral arteriovenous fistulas associated with intraparenchymal varix in childhood: case reports.

This report describes three children, each of whom developed an unusual malformation consisting of one or more intracerebral arteriovenous fistulas and a large intraparenchymal venous varix. Their clinical symptoms were similar to those produced by aneurysms of the vein of Galen: increasing head circumference, seizures, hemorrhage, and developmental delay. We treated each child with endovascular embolization and/or surgery and obtained complete closure of all fistulas without mortality.

Arteriovenous Fistula↗
PubMed1990

Antimigraine treatment for slit ventricle syndrome.

Slit ventricle syndrome is characterized by chronic or recurring headaches associated with subnormal ventricular volume in patients who have undergone shunt treatment for hydrocephalus. There appear to be at least three pathophysiological mechanisms that cause this syndrome: 1) intermittent shunt malfunction; 2) intracranial hypotension; and 3) paroxysms of increased intracranial pressure in the presence of normal shunt function. To treat seven patients with slit ventricle syndrome caused by paroxysms of elevated intracranial pressure, we successfully used antimigraine therapy rather than standard calvarial expansion procedures. None of these patients has required shunt revision or calvarial expansion during a mean follow-up period of 2 years. The symptoms of slit ventricle syndrome may be a form of "acquired" migraine in shunt patients. We suggest that, in clinically stable patients with normal shunt function, treatment against migraine may stabilize symptoms resulting from paroxysms of increased intracranial pressure. Such treatment may prevent unnecessary shunt revisions and/or calvarial expansion procedures.

Adult↗
PubMed1979

Reproductive function in temporal lobe epilepsy: the effect of temporal lobectomy.

We have examined sexual and reproductive changes in 25 patients (11 men and 14 women; mean follow-up 13 years) with temporal lobe epilepsy who underwent temporal lobectomy. Five men and two women had sexual dysfunction preoperatively, in particular, decreased libido. This improved after temporal lobectomy in three of these patients. One woman developed a partial Klüver-Bucy syndrome. Reproductive dysfunction was present in one man (oligospermia) and in ten women (four had the onset of seizures either at pregnancy or menarche; four had increased frequency of seizures during menarche or pregnancy, and two had amenorrhea). The man fathered two children post-operatively, and an appreciable improvement in both the seizure activity and the reproductive dysfunction was noted in the majority of the women.

Adolescent↗
PubMedDate not supplied

Prognostic significance of molecular genetic markers in childhood brain tumors.

Molecular genetic analysis of several common cancers has yielded information concerning their etiology and prognosis. Restriction fragment length polymorphism (RFLP) studies showing consistent loss of specific DNA sequences in tumor tissue have identified genes, known as tumor suppressors, associated with the etiology of neoplasms of the adult colon, breast, lung, and brain. For several of these tumors, identifiable mutations of these genes in association with multiple chromosomal losses have been linked to a poor clinical outcome. Using RFLP and other techniques, we have determined that one or more tumor suppressor genes on chromosome 17p is involved in the etiology of both medulloblastoma and astrocytoma in children. Loss of chromosome 17p sequences is indicative of prognosis negative for these children. Molecular genetic data therefore supplement and in some cases surpass clinical criteria in predicting prognosis for these childhood tumors.

Brain Neoplasms↗
PubMedDate not supplied

Congenital nasal masses: CT and MR imaging features in 16 cases.

The imaging studies of 16 children with pathologically proved nasal encephaloceles (eight), nasal dermal sinuses/nasal dermoids (seven), and nasal cerebral heterotopias, more commonly known as nasal gliomas (one), were retrospectively reviewed and compared with normal control subjects to define the normal anatomy and analyze deformities caused by these lesions. Nasal encephaloceles were always identified as complex masses of mixed soft tissue and CSF intensity that were contiguous with intracranial structures. The nasal glioma appeared as a mixed-intensity mass that, on the basis of the CT scan, appeared to be continuous with intracranial structures. Nasal dermal sinuses could only be identified as they coursed through the skin and subcutaneous soft tissue. They could not be identified when intraosseous. Moreover, on CT and, particularly, on MR, a number of potential diagnostic pitfalls were encountered. The most important of these was the normal fat deposition that occurs within bone during normal maturation and during aeration of the frontal sinuses and nasal bones. These fatty changes can easily be mistaken for fatty tumors if they are not recognized as normal anatomic changes. Interestingly, the classic plain film findings for congenital nasal masses were present only in the encephaloceles and nasal glioma; dermoids and dermal sinuses showed none of the classic plain film findings. In the six patients who had both CT and MR, the masses were easily identified and characterized by each imaging method. Congenital nasal masses are well characterized by both CT and MR. It is important to understand the normal changes in the anatomy of the nasofrontal region in the pediatric age group to avoid false-positive diagnoses in this region.

Child↗
PubMedDate not supplied

MR evaluation of spinal dermal sinus tracts in children.

The MR studies of seven pediatric patients with surgically proved spinal dorsal dermal sinuses were reviewed retrospectively. Five of the seven had associated congenital tumors (three epidermoids, two dermoids). The subcutaneous portions of the spinal tracts and intramedullary portions of tumor were easily identified with the use of standard spin-echo techniques. However, except for limited areas where they were lined by fat, the intraspinal portions of the dermal sinuses were poorly seen. Moreover, diffuse subarachnoid tumor was missed in two patients. Three-dimensional Fourier transform gradient-echo acquisition using a volumetric radiofrequency pulse as a "spoiler" proved to be helpful in evaluating these abnormalities. Optimal radiologic workup of patients with dorsal dermal sinuses awaits the development of new MR imaging sequences. For now, heavily T1-weighted MR sequences should be obtained and supplemented with sonography in infants and with CT myelography in older children.

Child↗