Biomedical subjects

N S Karp

Publications and source records attributed to N S Karp.

8 recordsLinked to original sources

PubMed1992

Membranous bone lengthening: a serial histological study.

Bone lengthening using the process of corticotomy and gradual distraction of callus is applicable to the membranous bone of the canine mandible. In this study the precursors to bone formation, in the area between the distracted bone edges, are analyzed in an attempt to determine the mechanism of bone formation. Ten mongrel dogs 5 months of age were studied. A unilateral, periosteal-preserving angular corticotomy was performed, and an external bone-lengthening device was fixed to the mandible. After 10 days of external fixation, the mandible was lengthened 1 ml per day for 20 days and then held in external fixation for 8 weeks. The dogs were killed for histological and microradiographic study at 10 and 20 days of distraction, and at 14, 28, and 56 days after the completion of distraction. It was observed that the gap between the distracted bone edges is first occupied by fibrous tissue. As distraction proceeds, the fibrous tissue becomes longitudinally oriented in the direction of distraction. Early bone formation advances along the fibrous tissue, starting from the cut bone ends. Eventually the area is converted to mature cortical bone. Bone is formed predominantly by intramembranous ossification. This mechanism is similar to that of bone formation during long bone lengthening.

Animals↗

PubMed1992

Maximizing gain from rectangular tissue expanders.

Three different options are proposed to cut the flap after expansion of rectangular tissue expanders. Each method, when used effectively, allows the expander to deliver the full punch of the expansion process.

Cheek↗

PubMed1991

Survival with regional and distant metastases from cutaneous malignant melanoma.

The clinical course of 312 consecutive patients after initial presentation with metastatic melanoma, 165 of whom presented with regional metastases at cutaneous or subcutaneous, or both, nodal sites and 147 with metastases at distant sites, was reviewed. The five year survival rate for regional metastases was 43.4 per cent compared with a five year survival rate for distant metastases of 4.9 per cent (p less than 0.0001). Favorable prognostic variables for survival from first regional metastases included primary melanoma sites on the extremities compared with the head, neck and trunk (p = 0.043) and a disease-free interval of more than one year from primary surgical treatment to regional metastases (p = 0.0058). Favorable prognostic variables for survival from the first distant metastasis included a disease-free interval of more than one year from primary surgical treatment to distant metastases (p = 0.0092), the type of resection of metastatic disease (p = 0.00027) and the addition of systemic immunotherapy (p = 0.0011). Forty-nine patients with totally resectable distant metastases had a five year survival rate from the treatment of the initial metastasis of 13.1 per cent, whereas 33 patients having palliative resections had a five year survival rate of 7.5 per cent. All 165 patients who did not have resection for distant metastases died within five years. The results of our experience support therapeutic efforts to ablate both regional and distant metastases of malignant melanoma when feasible.

Adult↗

PubMed1990

A comparison of two approaches to three-dimensional imaging of craniofacial anomalies.

Volume-based and surface-based algorithms for three-dimensional rendering of computed tomography (CT) scans of the human skull were compared in patients with craniofacial anomalies. Both methods were applied to a selected sample of 12 clinical CT studies. The number of sections ranged from 24 to 72 and the section thickness from 1.5 to 6.0 mm. Volume renderings were more prone to interpolation artifacts but captured the anatomy in greater detail. The sites of closed cranial sutures, visualized using the volume technique, were not demonstrated using the specific surface rendering technique used in this study. In both techniques the areas of thin bone appeared as gaps.

Adolescent↗

PubMed1990

Bone lengthening in the craniofacial skeleton.

The process of bone lengthening by cortical fracture and gradual distraction of callus has become well established in the enchondral bones of the extremities. In this study the principles of bone lengthening were applied to the membranous bone of the craniofacial skeleton using the growing dog mandible as a model. Six mongrel dogs five months of age were studied. A unilateral, periosteal-preserving angular corticotomy was performed, and an external minilengthening device was fixed to the mandible perpendicular to the corticotomy. After 10 days of external fixation, the mandible was lengthened 1 mm/day for 20 days and then held in external fixation for 56 days (8 weeks) after which all dogs were killed. Anthropometric measurements and histological analysis of the specimens confirmed that bone lengthening had occurred and that new cortical bone was formed in the expanded areas.

Animals↗

PubMed1990

The effect of early fronto-orbital advancement on frontal sinus development and forehead aesthetics.

The frontal sinuses make an important contribution to normal forehead and glabellar contour. This study was designed to test our clinical impression that early fronto-orbital ("frontal bone") advancement could have an adverse effect on frontal sinus development and consequently on forehead aesthetics. A retrospective study was conducted on 11 patients who had undergone fronto-orbital advancement and also had a long period of follow-up at the Institute of Reconstructive Plastic Surgery at New York University. The longitudinal cephalometric data were compared with unoperated controls. With one exception, no patient who underwent bilateral fronto-orbital advancement developed a frontal sinus, and all such patients had a flattened brow contour when compared with unoperated patients, of whom 82 percent developed at least one frontal sinus. Of the three patients who underwent unilateral fronto-orbital advancement for plagiocephaly (flattened forehead), two developed a frontal sinus but only on the unoperated side and one developed bilateral frontal sinuses. The two patients with unilateral frontal sinus development had a particularly obvious deformity resulting from normal glabellar projection on the unoperated side and a flattened contour on the operated side. Fronto-orbital advancement affects forehead aesthetics and should be performed only in infant patients with moderate to severe deformities. patients with plagiocephaly whose deformity is sufficiently severe to warrant surgery should preferably undergo bilateral fronto-orbital advancement (by the technique described) rather than unilateral advancement in order to avoid the brow asymmetry that results from unilateral frontal sinus development.

Adolescent↗

PubMed1990

Thoracotomy for metastatic malignant melanoma of the lung.

The outcome of 29 patients who underwent lung resection for treatment of metastatic malignant melanoma from January 1976 to November 1988 was studied. Twenty-two patients underwent total resection for cure of all apparent metastatic disease, whereas seven patients did not undergo total resection. Of the 22 patients who underwent curative resection, the median survival was 11 months, with a 2-year survival of 13.6% and a 5-year survival of 4.5%. Four patients who underwent curative resection are currently alive and free of disease, with one patient surviving more than 10 years. The patients who underwent palliative resection had a median survival of 5 months, only one patient living longer than 10 months. The difference in survival of the patients who underwent curative resection compared with palliative resection was statistically significant. The thickness of the primary cutaneous malignant melanoma, the presence of regional lymph node metastases, the disease-free interval from primary diagnosis to metastatic pulmonary disease, and whether one or two metastatic nodules were removed during curative lung resection were not statistically significant in altering survival. These results demonstrate that although prolonged survival for metastatic melanoma is rare, lung resection in selected patients may be associated with long-term survival.

Adult↗

PubMed1989

Primary hyperparathyroidism associated with two enlarged parathyroid glands.

An increasingly recognized although small percentage of patients with primary hyperparathyroidism have enlargement of two parathyroid glands. We have treated nine patients with primary hyperparathyroidism associated with such double parathyroid gland enlargement. In four of these patients, marked asymmetry of the two enlarged glands was noted and the failure to recognize and excise a second enlarged parathyroid gland resulted in persistent or recurrent hyperparathyroidism. In one of these patients, the second enlargement was present in a super-numerary mediastinal gland. The subsequent excision of the second enlarged parathyroid gland resulted in normocalcemia in each instance. This contrasts with five patients in whom initial excision of two enlarged glands resulted in normocalcemia with no recurrence of hypercalcemia. Only three patients fulfilled the histologic criteria of true double adenomas. The remainder showed multiglandular hypercellularity. This experience supports identifying all parathyroid glands and recognizing that even minimal enlargement of a gland may be important pathophysiologically, regardless of its histopathologic classification. Excision of both enlarged glands, even if asymmetric, is appropriate.

Adult↗