Search PubMed⌕ Search

Biomedical subjects

B M Greenberg

Publications and source records attributed to B M Greenberg.

At least 37 records · Page 2Linked to original sources
PubMed1993

A preliminary report on the use of laser-Doppler flowmetry during tethered spinal cord release.

Neurological deterioration in the tethered cord syndrome has been postulated to result from a compromise of blood flow in the distal spinal cord. In order to evaluate vascular perfusion in human subjects, a new technique of laser-Doppler flowmetry was used to monitor continuously the microcirculation of the distal spinal cord during surgery for tethered cord release in 10 children. For further comparison, five children undergoing selective dorsal rhizotomy were also monitored. In the tethered cord syndrome group, spinal cord blood flow before untethering was a mean of 12.6 ml/min per 100 g of tissue and increased in all cases after release to a mean of 29.4 ml/min per 100 g of tissue. All patients improved neurologically. The selective dorsal rhizotomy group had a preoperative mean spinal cord blood flow of 30.8 ml/min per 100 g of tissue, which was not altered by the operative procedure. Significant improvement occurs in distal spinal cord blood flow after tethered cord release, which may be representative of an important mechanism in the pathophysiology of the tethered cord syndrome.

Adolescent↗
PubMed1992

A socioeconomic analysis of digital replantations resulting from home use of power tools.

Forty-seven digits in 21 patients who sustained partial or complete amputations from the home use of power tools were replanted or revascularized during a 1-year period. This represented 69% of the microvascular surgery performed for hand injuries during that year. The cost of repairing an average of 2.4 digits was $7000 (surgeon's fee) plus $697 per hour (operating room fee), as per fiscal year 1987. Postoperative hospitalization averaged 15 days at a cost of $15,679. Hand rehabilitation averaged 8 months at a cost of $3348. Fifty-four percent of the patients had no insurance. Fourteen of 21 patients (67%) required at least one additional procedure. Two patients had to make a career change after the injury. The majority of patients with digital replantations were dissatisfied with the emotional costs and the number of subsequent operations. Lack of patient and family awareness of the length of the rehabilitative period was particularly evident.

Accidents, Home↗
PubMed1992

Use of an inferiorly based rectus muscle flap in flank wound coverage.

An inferiorly based rectus island flap was used to repair a large infected hip wound resulting from treatment of a posteriorly dislocated-comminuted acetabular fracture. The muscle island flap (based on the inferior epigastric vessels) allowed an extended arc of rotation to cover this laterally located wound.

Acetabulum↗
PubMed1992

Differential Synthesis of Photosystem Cores and Light-Harvesting Antenna during Proplastid to Chloroplast Development in Spirodela oligorrhiza.

Proplastids and etioplasts are common starting points for monitoring chloroplast development in higher plants. Although proplastids are the primary precursor of chloroplasts, most proplastid to chloroplast systems are cumbersome to study temporally. Conversely, the etioplast to chloroplast transition is initiated by light and is readily examined as a function of time. Etioplasts, however, are found mostly in plants germinated in the dark and are not an obligatory step in chloroplast development. We have chosen to study chloroplast ontogeny in Spirodela oligorrhiza (Kurtz) Hegelm (a C(3)-monocot) because of its unique ability to grow indefinitely in the dark. Ultrastructural, physiological, and molecular evidence is presented in support of a temporal, light-triggered proplastid to chloroplast transition in Spirodela. The dark-grown plants are devoid of chlorophyll, and upon illumination synchronously green over a 3- to 5-day period. Synthesis of chloroplast proteins involved in photosynthesis is coincident with thylakoid assembly, chlorophyll accumulation, and appearance of CO(2) fixation activity. Interestingly, the developmental sequence in Spirodela was slow enough to reveal that biosynthesis of the D1 photosystem II reaction center protein precedes biosynthesis of the major light-harvesting antenna proteins. This, coupled with the high chlorophyll a/b ratio observed early in development, indicated that reaction center assembly occurred prior to accumulation of the light-harvesting complexes. Thus, with Spirodela one can study proplastid to chloroplast conversions temporally in higher plants and follow the process on a time scale that enables a detailed dissection of plastid maturation processes.

Journal Article↗
PubMed1991

Efficacy of intraarterial heparin in maintaining microvascular patency: an experimental model.

Human-grade sodium heparin was studied to determine thrombosis model patency rates between an intraarterial infusion versus an intravenous method of delivery in a rabbit model. Specific differences in patency and partial thromboplastin times were studied in each group and compared with a saline-perfused group. Three animal groups (New Zealand white rabbits) were established (total = 35 animals). Standardized femoral arterial 5-mm inversion grafts (AIG) were done in each animal in each group. The animals in the control group received intravenous saline infusion, while the two treatment groups received intravenous heparin (12 animals) or intraarterial heparin (12 animals minus 1 anesthesia death). The route of instillation of the infusate was selected at random after completing the inversion grafts. A proximal epigastric branch was utilized for access in those animals randomized to the intraarterial group. Intravenous delivery was accomplished by means of a femoral venous catheter in the vena cava. A 72-hour period of infusion was used in all animals. A dose of 45 units per hour of heparin following a 500-unit bolus was used in the intravenous group. After an identical bolus dose, 25 units per hour of heparin was administered in the intraarterial group. The control (saline group) was given 1 cc saline (in a volume equal to the heparin-dosed groups) daily for 3 days. Arterial inversion graft patency rates were assessed by direct inspection at day 5. Systemic and regional (i.e., distal to the inversion graft) partial thromboplastin times (PTT) were measured in representative control, IV, and intraarterial heparin-treated groups. Complications were recorded.(ABSTRACT TRUNCATED AT 250 WORDS)

Anastomosis, Surgical↗
PubMed1991

Avianca flight No. 052 accident: a plastic surgical perspective.

The crash of Avianca Airlines flight no. 052 en route to JFK Airport on January 25, 1990, in Cove Neck, New York, resulted in the death of 72 passengers. Eighty-nine victims were admitted to 13 regional hospitals. Despite difficult access to the wooded crash site, early warning and prompt response by 37 volunteer fire and rescue units resulted in organized EMS triage and rapid hospital transport. This report reviews the specific injuries incurred, highlights the team management approach to a major aviation accident in a suburban area, and studies the likelihood of accidents of this magnitude. Thirty-eight patients triaged to two level I trauma centers, North Shore University Hospital-Cornell University Medical Center and Nassau County Medical Center, form the basis of this report. Seventeen patients were male; 21 were female. The average patient age was 33 years. Eight patients were children. The average length of stay was 30.9 days (range 2 to greater than 90 days). Twenty-six patients (including nonsurvivors) (68 percent) sustained significant multiple orthopedic injuries. The majority of fractures were open grade II to III tibia-fibula fractures. Bilaterality was commonly seen. Soft-tissue coverage of open long bone fractures was required in 10 patients (11 extremities) and included 3 microvascular muscle transfers, 7 muscle transposition flaps, and 3 skin grafts. Seven patients required open reduction and fixation of complex facial fractures (two of Le Fort II to III type, four of complex naso-orbital-ethmoid type). Plastic surgical repair of complex lacerations was common. Peripheral nerve exploration was required in three patients.(ABSTRACT TRUNCATED AT 250 WORDS)

Accidents, Aviation↗
PubMed1991

Congenital bifid sternum: repair in early infancy and literature review.

Sternal clefting is an unusual congenital anomaly that should be repaired in early infancy. Early surgery is facilitated by a highly compliant bony thorax. The surgical technique is described, including the (1) removal of a wedge at the confluence of the two lateral sternal bands to allow their apposition, (2) intraoperative assessment of pulmonary compliance and central venous pressure, (3) use of bilateral pectoral flaps, and (4) resulting avoidance of major costochondral stair-step osteotomies. The suggested age of repair is 1 to 4 weeks of age.

Humans↗
PubMed1990

D1-D2-cytochrome b559 complex from the aquatic plant Spirodela oligorrhiza: correlation between complex integrity, spectroscopic properties, photochemical activity, and pigment composition.

A D1-D2-cyt b559 complex with about four attached chlorophylls and two pheophytins has been isolated from photosystem II of the aquatic plant Spirodela oligorrhiza and used for studying the detergent-induced changes in spectroscopic properties and photochemical activity. Spectral analyses (absorption, CD, and fluorescence) of D1-D2-cyt b559 preparations that were incubated with different concentrations of the detergent Triton X-100 indicate two forms of the D1-D2-cyt b559 complexes. One of them is photochemically active and has an absorption maximum at 676 nm, weak fluorescence at 685 nm, and a strong CD signal. The other is photochemically inactive, with an absorption maximum at 670 nm, strong fluorescence at 679 nm, and much weaker CD. The relative concentrations of the two forms determine the overall spectra of the D1-D2-cyt b559 preparation and can be deduced from the wavelength of the lowest energy absorption band: preparations having maximum absorption at 674, 672, or 670.5 nm have approximately 20, 60, or 85% inactive complexes. The active form contains two chlorophylls with maximum absorption at 679 nm and CD signals at 679 (+) and 669 nm (-). These chlorophylls make a special pair that is identified as the primary electron donor P-680. The calculated separation between the centers of these two pigments (using an extended version of the exciton theory) is about 10 A, the pigments' molecular planes are tilted by about 20 degrees, and their N1-N3 axes are rotated by 150 degrees relative to each other. The other two chlorophylls and one of the two pheophytins in the D1-D2-cyt b559 complex have their maximum absorption at 672 nm, while the maximum absorption of the photochemically active pheophytin is probably at 672-676 nm. During incubation with Triton X-100, the photochemically active complex is transformed into an inactive form with first-order kinetics. In the inactive form the maximum absorption of the 679 nm absorbing Chls is blue-shifted to 669 nm. The first-order decay of the photochemical activity suggests that the isolated D1-D2-cyt b559 complex is stable as an aggregate but becomes unstable on dissociation into individual D1-D2-cyt b559 units.

Chlorophyll↗
PubMed1990

Comparative bacterial clearances of muscle and skin/subcutaneous tissues with and without dead bone: a laboratory study.

Seventeen New Zealand White rabbits underwent implantation of three different concentrations of bacteria and a sterile saline control solution with and without dead autologous bone in eight separate muscular and eight separate subcutaneous sites. Following a period of 1 week, each site was surgically explored and samples of tissue were taken for histology and quantitative culture. Results reveal that final bacterial concentrations in the subcutaneous sites were significantly lower than in the muscle sites (p less than or equal to 0.0001) for each concentration of bacteria, with and without dead bone. Dead bone resulted in very significantly greater bacterial concentrations in both subcutaneous and muscle sites. Clinically, these results indicate that a thorough bony wound debridement is more important than the type of tissue used to close the wound. Flap tissue should be selected with regard to the perfusion, contour, and appearance of the recipient site.

Abscess↗
PubMed1989

Separate photosensitizers mediate degradation of the 32-kDa photosystem II reaction center protein in the visible and UV spectral regions.

A component of the photosystem II reaction center, the 32-kDa protein, is rapidly turned over in the light. The mechanism of its light-dependent metabolism is largely unknown. We quantified the rate of 32-kDa protein degradation over a broad spectral range (UV, visible, and far red). The quantum yield for degradation was highest in the UVB (280-320 nm) region. Spectral evidence demonstrates two distinctly different photosensitizers for 32-kDa protein degradation. The data implicate the bulk photosynthetic pigments (primarily chlorophyll) in the visible and far red regions, and plastoquinone (in one or more of its redox states) in the UV region. A significant portion of 32-kDa protein degradation in sunlight is attributed to UVB irradiance.

Chlorophyll↗
PubMed1989

Correlation of postoperative bone scintigraphy with healing of vascularized fibula transfer: a clinical study.

This study examines the usefulness and reliability of bone scintigraphy in correlation with radiological and clinical evidence of bone healing in 15 patients who underwent microvascular transfer of the fibula. All patients were followed for a minimum of 18 months postoperatively. Technetium-99 methylene diphosphonate bone scans and the most recent radiographs were blindly rereviewed. Bone scintigraphic results were characterized as (1) clearly positive (i.e., excellent visualization of the fibula), (2) clearly negative (i.e., no evidence of tracer uptake in the fibula), or (3) indeterminate (i.e., artifact present as a result of metallic or soft tissue interference). Bone radiographs were classified into three typical patterns: (1) complete bony union and graft hypertrophy, (2) incomplete union (either distal or proximal) requiring a second procedure), and (3) nonunion, with increased proximal and distal lucency (with or without pathological fracture) and loss of graft definition. Eleven patients had positive scintigraphic scans postoperatively. In 8 no subsequent procedure was necessary; 2 patients required additional bone grafts to augment the osseous reconstruction; viable fibulas were seen at reoperation. One patient with a positive scan showed decreased graft definition at four months followed by autograft fracture. Three patients had indeterminate scans, 2 of whom evidenced uncomplicated clinical and radiological union. One patient had a clearly negative scan and ultimately tibia-fibula synostosis was required to attain stability. Bone scintigraphy appears to correlate with survival, but not necessarily union, of a vascularized fibula autograft. Additional monitoring techniques should be used in combination with a one-time bone scan to both monitor the patency of the microanastomoses and to prioritize the orthopedic management of the patient.

Arteries↗
PubMed1988

St. Clair Strange procedure: indications, technique, and long-term evaluation.

The pedicled ulnar nerve transfer (St. Clair Strange procedure) preserves the intrinsic blood supply to the transferred nerve and allows bridging of large defects in avascular, scarred wounds. We report our indications for this operation, describe the two operative stages, and report the results in seven patients. After operation progressive median nerve axonal growth in a proximal direction up the ulnar nerve was shown by a median nerve Tinel's sign. Five patients followed for a mean of 10 years achieved protective sensibility in the median nerve distribution. In two of the three patients in whom distal nerve repair was done to the median and ulnar nerve, protective sensibility also returned to the ulnar digits. Localization, stereognoses, and vibratory response was achieved in the majority of digits. All patients had active use of the hand, but none had meaningful two-point discrimination. No changes were found after a superficial radial nerve block excluded any radial nerve contribution. No intrinsic motor functional return was noted. Two patients are currently being followed.

Adolescent↗
PubMed1988

Successful localization of parathyroid adenomas by magnetic resonance imaging.

Exploration of the neck for primary hyperparathyroidism is facilitated if the parathyroid glands can be localized preoperatively. Magnetic resonance imaging is a noninvasive and relatively safe procedure that is capable of distinguishing and differentiating small soft-tissue structures. Ten patients with primary hyperparathyroidism underwent preoperative diagnostic magnetic resonance imaging followed by cervical exploration. In 9 of these patients (90 percent), imaging correctly predicted the location of a single enlarged parathyroid gland, and in one patient the findings were misleading. All 10 patients proved to have single adenomas in orthotopic locations. Based on this early experience, magnetic resonance imaging appears to be a promising technique for preoperative localization of an enlarged parathyroid gland.

Adenoma↗
PubMed1988

Great toe-to-hand transfer: role of the preoperative lateral arteriogram of foot.

This report correlates the results of the lateral angiogram of the foot with the operative dissection and eventual outcome in 29 patients in whom a great toe-to-hand transfer was performed to treat a traumatic loss of the thumb. Our angiographic findings were confirmed by surgical exploration and indicated that (1) in 20 (70%) of 29 patients the first dorsal metatarsal artery (FDMA) originated from the dorsalis pedis artery, dorsal to the midlongitudinal axis of the first metatarsal bone; (2) in 6 (20%) of 29 patients the FDMA originated from the dorsalis pedis artery, plantar to the midlongitudinal axis of the first metatarsal bone; (3) in the remaining 3 (10%) of 29 patients the arteriogram of the lateral foot indicated that the plantar metatarsal artery supplied the great toe in a dominant pattern, necessitating its use as the donor vessel; and (4) the measured lumenal diameters of the dorsal and plantar metatarsal arteries (mean diameter = 1.30 mm and 1.27 mm, respectively) did not significantly differ. The lateral views of the foot were helpful in permitting distinct identification of the location and size of the metatarsal arteries to the great toe.

Amputation, Traumatic↗
PubMed1988

Therapeutic value of intravenous heparin in microvascular surgery: an experimental vascular thrombosis study.

In an attempt to decrease a 10 to 15 percent vascular thrombosis rate leading to graft occlusion, low-dose human-grade heparin was studied to determine if carefully monitored intravenous therapy would increase 7-day patency in a known potent thrombosis model. In New Zealand white rabbits, the type of infusate administered intravenously, either saline (30 animals) or heparin (35 animals), was selected at random after completing a 2-mm arterial inversion graft in the femoral artery. A 72-hour infusion was used in all animals; the control group received sterile saline and the experimental group received a heparin infusion at 45 microliters per hour after a 500-unit bolus. All grafts in both groups were patent at the time of groin closure. Patency in the heparin-perfused group was 67 percent (24 of 35) as compared to 19 percent (6 of 30) in the control group (p less than 0.05) 1 week postoperatively. Scanning electron microscopy showed significantly less dense fibrin deposition and a decrease in the number of aggregated platelets in the heparin-perfused grafts. Partial tissue thromboplastin time values in the experimental group ranged between 55 and 75 seconds (control 20 to 25 seconds). We have shown that heparin, an inexpensive and readily available agent, maintains 1-week microarterial patency and results in few complications in a reliable, reproducible, and versatile thrombosis model. The clinical ramifications of using an antiplatelet agent that diminishes fibrin deposition in microsurgery are apparent.

Animals↗