Search PubMed⌕ Search

Biomedical subjects

H Weinberg

Publications and source records attributed to H Weinberg.

At least 91 records · Page 5Linked to original sources
PubMed1989

The effects of a topical PGE2 analogue on global flap ischemia in rats.

The present study evaluated the ability of DHV-PGE2ME, a topically effective 16-vinyl prostaglandin E2 analogue, to improve the tolerance of skin flaps to a period of ischemia. DHV-PGE2ME and placebo were applied to bilateral island flaps on 70 anesthetized rats; then the vascular pedicle of each flap was clamped for 10 hours. Treated flaps evidenced significantly better reperfusion, as documented by quantification of fluorescein dye delivery at 90 minutes after clamp release, and they had significantly greater ultimate viability (p less than 0.05, by ANOVA). While less than 3 percent of untreated flaps survived, those treated with 1.75 and 17.5 microgram/cm2 of drug evidenced 76 and 86 percent survival, respectively. Treatment of a given flap did not affect its contralateral mate, since there was no evidence of a systemic effect. Especially since its effect can be limited to the site of application, DHV-PGE2ME should be valuable for the treatment of compromised perfusion in a variety of settings.

Administration, Topical↗
PubMed1989

Primary placement of osseointegrated implants in microvascular mandibular reconstruction.

The goal of mandibular reconstruction is to rehabilitate the patient by restoring occlusal relationships, lower facial contour, oral continence, and a denture-bearing surface. One of the major advantages of the use of vascularized bone over all other methods of mandibular reconstruction is its ability to achieve dental rehabilitation rapidly. The use of osseointegrated dental implants is a valuable adjunct in oral rehabilitation. It provides the most rigid form of stabilization to withstand the forces of mastication. In situations in which soft tissue reconstruction or the height of the alveolar ridge is not sufficient for a tissue-borne denture, implants offer the most suitable alternative. Mandibular reconstruction with free tissue transfer techniques is ideally suited for the placement of implants. These can be inserted at the time of mandibular reconstruction. Four months after surgery, when the integration process has occurred, the implants are unroofed, loaded, and ready for prosthetic placement. We will present several representative patients who underwent mandibular reconstruction with microvascular free bone transfer who have been successfully rehabilitated by osseointegrated implants. The process of osseointegration, different types of dental implants, and issues regarding radiation and implants are discussed. This is the first report of dental rehabilitation by primary placement of dental implants in patients undergoing microvascular mandibular reconstruction.

Adenocarcinoma, Bronchiolo-Alveolar↗
PubMed1988

Comparison of skin surface fluorescence and fluorescein tissue concentration with the dermatofluorometer.

Recently sodium fluorescein has been used to determine viability of tissue and assess blood flow. No study, however, has documented the correlation of surface fluorescence as measured by the dermatofluorometer with the actual distribution of fluorescein in tissue. Abdominal skin flaps were raised on Sprague-Dawley rats. Following intravenous injection of sodium fluorescein, skin surface fluorescence was measured and compared with tissue fluorescein concentration. This study confirms that skin surface fluorescence correlates well with actual fluorescein distribution in tissue. Furthermore, the study clearly illustrates the statistically significant variation of surface fluorescence as a function of distance from the vascular pedicle.

Animals↗
PubMed1988

The distribution of extracellular matrix vesicles in healing of rat tibial bone three days after intramedullary injury.

The distribution of extracellular matrix vesicles on the third day of bone healing was studied by morphometric analysis of transmission electron micrographs. Detection and grouping of the vesicles was performed according to type, diameter, and distance from the calcified front. The different types were selected as follows: vesicles with electron-lucent contents ("empty"), vesicles with amorphous electron-opaque contents ("amorphic"), vesicles containing crystalline depositions ("crystal"), and vesicles containing crystalline structures with ruptured membranes ("rupture"). The majority of vesicles were between 0.07 micron and 0.12 micron in diameter and were located at less than 3 micron from the calcified front. The distribution of the "empty", "amorphic", "crystal", and "rupture" vesicles was 23.2%, 74%, 2.5%, and 0.3% respectively. Their sequence of arrangement according to diameter was as follows: "empty", "amorphic", "crystal", and "rupture", the empty vesicles constituting the smallest and the "rupture" the largest type. Distances from the calcified front were similar for the "empty", "amorphic", and "crystal" vesicles, while the "rupture" type was located nearest to the front. The present observations support the widely acknowledged hypothesis on the role of extracellular matrix vesicles in mineralization. It is thought that the secretion of "empty" vesicles from the cell is followed by intravascular accumulation of amorphous Ca and Pi to form a hydroxyapatite crystal that, in turn, ruptures the vesicle's membrane.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1988

Topographic distribution of the 40 Hz auditory evoked-related potential in normal and aged subjects.

Galambos, Makeig and Talmachoff (1981) described what they called the 40 Hz event-related potential (ERP). This steady-state response is an EEG following response to repetitive auditory stimulation which becomes sinusoidal in form and maximal in amplitude at rates between 35 and 45 Hz. The present study was designed to examine the scalp topography of the 40 Hz ERP in order to complement previous magnetoencephalographic studies which implicate auditory cortex in the generation of the response. In addition, this study was designed to collect normative data on an aged sample in order to assess the effects of aging on the response. 40 Hz ERP's were recorded from a group of seven audiometrically and neurologically normal elderly subjects (mean age = 69.6 years) and a younger group of five normal adults (mean age = 38.0 years), using 1000 Hz tones presented binaurally at 40 per second. A 21 channel recording system was used to obtain a comprehensive picture of the scalp distribution of the response. Recorded ERP's were Fourier transformed to enhance the signal-to-noise ratio. No significant differences were found in phase or amplitude of the 40 Hz ERP between the two age groups, indicating that the normal aging process does not have an effect on this response. Topographic maps of the 40 Hz ERP showed reversals of electrode potential in temporal regions, supporting an interpretation of bilateral sources in temporal cortex. The data presented in this study complement previous studies of the 40 Hz event-related magnetic field and support the position that temporal cortex is involved in the generation of the response.

Acoustic Stimulation↗
PubMed1988

Personality and smokeless tobacco use.

Smokeless tobacco use and personality factors associated with smokeless tobacco use were examined in a broad, representative sample of 8th and 10th graders from central and south-central Florida (n = 1413). Current, occasional, or ex-users of smokeless tobacco accounted for 51% of the males and 9% of the females. Smokeless tobacco users, as compared to non-users, had significantly higher Trait Anger, and Angry Temperament and Angry Reaction subscale scores on the State-Trait Personality Inventory, suggesting a possible role in the initiation of smokeless tobacco use. There were no differences in Trait Anger, Anxiety, or Curiosity scores between the three user groups, suggesting that trait personality does not play a role in the maintenance of smokeless tobacco use.

Adult↗
PubMed1988

The relationship between extracellular matrix vesicles and the calcifying front on the 21st day after injury to rat tibial bone.

The relationship between extracellular matrix vesicles and the calcifying fronts was examined by studying vesicular diameters and types. Transmission electron microscopy combined with computerized morphometry three weeks after injury to the tibial bone in rats was used. The different vesicle types were defined as: (1) vesicles with electron lucent contents referred to as empty; (2) vesicles with amorphous electron opaque contents, called amorphic; (3) vesicles containing crystalline depositions, called crystalline; and (4) vesicles containing crystalline structures with ruptured membranes, referred to as ruptured. The diameters of most vesicles ranged between 0.07 and 0.17 micron. More than 95% of the vesicles were located less than 2 micron from the calcified front. The vesicles were distributed among the categories as follows: empty, 9.6%; amorphic, 19.3%; crystal, 39.2%; and ruptured, 31.9%, respectively. The diameters of the crystalline and ruptured vesicles were significantly larger than those of the empty and amorphic types. The ruptured type had the largest diameters. The sequence of distances from the calcified front was recorded as follows: ruptured, crystalline, amorphic, and empty, with the ruptured and crystalline types being the closest to the front. This study supports the accepted theory on matrix vesicle mineralization. The cell is responsible for secretion of empty vesicles that accumulate amorphous Ca and Pi to form a hydroxyapatite crystal. This is followed by rupture of the vesicular membrane. The propagation of the process is accompanied by an increase in the vesicular diameter and its approximation to the calcifying front.

Animals↗
PubMed1987

Extent of fiber regeneration after peripheral nerve repair: silicone splint vs. suture, gap repair vs. graft.

The degree of regeneration in surgically repaired sciatic nerves in rats was measured using a simple new electrophysiologic method: comparison of the size of nerve responses evoked by stimulation distal and proximal to the anastomosis. Five different repair procedures were evaluated. After simple end-to-end suture anastomosis, about 40% of the severed parent fibers regenerated past the suture line. The result was substantially improved when the anastomosis was covered with a newly designed thinwall silicone sheath which incorporated a narrow longitudinal slit. The presence of suture material at the point of anastomosis had no effect. Finally, regeneration across a 5-mm gap ensheathed in silicone (67%) was better than regeneration through a 5-mm autograft (45%).

Action Potentials↗
PubMed1987

Physico-chemical treatments for the complete removal of non-ionic surfactants from effluents.

Adsorption isotherms for a selection of non-ionic surfactants on activated carbons indicated the effectiveness of the latter in the removal of these pollutants from secondary effluents. The removal efficiencies were found to be improved when the secondary effluent was first flocculated with ferric chloride. This effectively removed some 80% of the non-ionic surfactant in the effluent. Batch adsorption experiments with powdered activated carbon removed 97% of the surfactant at low carbon dosage. A granular carbon with the best adsorption capacity was selected for continuous-flow operation in which non-ionic surfactants, COD and anionic surfactant alkyl benzene sulphonate were monitored. The breakthrough capacity for the non-ionic surfactants was in excess of 6000 bed volumes throughput of flocculated, sand-filtered effluent in a laboratory scale carbon column. Such a procedure is suggested for the complete removal of such pollutants from effluents.

Journal Article↗
PubMed1987

Changes in the distribution of extracellular matrix vesicles during healing of rat tibial bone (computerized morphometry and electron microscopy).

A study of the distribution of extracellular matrix vesicles during the first 3 weeks of healing of adult rat tibial bone was performed by transmission electron microscopy in combination with computerized morphometry. Bone injury comprised removal of the marrow followed by regeneration of the tissue via a phase of primary mineralization. A total number of 39,498 vesicles were traced on electron micrographs and sorted according to their diameters, distance from the calcified front and types. The different vesicular types were defined as follows: (a) vesicles with electron lucent contents, i.e. "empty", (b) vesicles with amorphous electron opaque contents, i.e. "amorphic", (c) vesicles containing crystalline depositions, i.e. "crystal", and (d) vesicles containing crystalline structures with ruptured membranes i.e. "rupture". The vesicles were studied on the days 3, 6, 14 and 21 after bone injury. Most of the vesicles were concentrated between diameters of 0.07 and 0.17 micron. Most of the vesicles were found in a distance less than 3 microns from the calcified front. The sequence of changes of distances from the calcified front and of the vesicular diameters were recorded as follows: "rupture", "crystal", "amorphic" and "empty", the "rupture" type being the closet to the front and of the largest diameter in each day. The results of the present study confirm the accepted hypothesis on calcification via extracellular matrix vesicles. It is thought that the cell secretes "empty" vesicles that accumulate Ca and Pi forming amorphous calcium phosphate that is then converted to hydroxyapatite. This is followed by rupture of the vesicular membrane.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1987

Dupuytren's disease as a cause of ulnar tunnel syndrome.

Two clinical cases of documented ulnar nerve compression in Guyon's canal caused by Dupuytren's disease are described. Surgical decompression of the canal promptly relieved the symptoms, and histologic studies confirmed the presence of Dupuytren's disease.

Adult↗
PubMed1987

Beneficial effects of ibuprofen on experimental microvascular free flaps: pharmacologic alteration of the no-reflow phenomenon.

Pharmacologic alteration of the no-reflow phenomenon was determined based on increased tolerance to ischemia in ibuprofen-treated free flaps. Sprague-Dawley rats (N = 60) were divided into control (lactated Ringer's) and treated (ibuprofen) groups and subdivided into six groups of ischemia: 1 hour, 6 hours, 8 hours, 10 hours, 12 hours, and 14 hours of ischemia. Fluorescein uptake was measured after 10, 30, and 60 minutes following microrevascularization. Dye elimination studies were done for each ischemia group that demonstrated good fluorescein uptake. All free flaps in the 1-, 6-, and 8-hour groups survived. The ibuprofen-treated 10- and 12-hour flaps all survived, whereas the 10-hour control and 14-hour ibuprofen-treated free flaps failed to survive. Despite high fluorescein uptake, the 14-hour ibuprofen-treated flaps did not eliminate the fluorescein, whereas all surviving free flaps adequately eliminated the fluorescein. Failure to eliminate dye despite adequate uptake suggested a deranged microcirculation with increasing ischemia time. By inhibiting cyclo-oxygenase, nonsteroidal anti-inflammatory agents such as ibuprofen may block the untoward effects mediated by thromboxane A2, such as vasoconstriction, microvasculature thrombus formation, and intravascular sludging. These effects are theorized in part to be responsible for the failure of a free flap to survive despite revascularization.

Animals↗
PubMed1987

Ultrastructural tissue morphometry of the distribution of extracellular matrix vesicles in remodeling rat tibial bone six days after injury.

A study of the distribution of extracellular matrix vesicles on the 6th day of bone healing was performed by methods of transmission electron microscopy combined with computerized morphometry. The vesicles were detected on the electron micrographs and grouped according to their diameters, distance from the calcified front and type. The different types were selected as follows: vesicles with electron-lucent contents, i.e., 'empty'; vesicles with amorphous electron-opaque contents, i.e., 'amorphous'; vesicles containing crystalline depositions, i.e., 'crystal', and vesicles containing crystalline structures with ruptured membranes, i.e., 'rupture'. Most of the vesicles were concentrated between diameters of 0.02 and 0.22 microns. Most of the vesicles were found within a distance of less than 3 micron from the calcified front. The vesicles were distributed according to their types: 'empty', 'amorphous', 'crystal' and 'rupture' in 14, 39, 34 and 13%, respectively. The diameters of the 'crystal' and 'rupture' vesicles were significantly larger than those of the 'empty' and 'amorphous' types. The sequence of distances from the calcified front was recorded as follows: 'rupture', 'crystal', 'amorphous' and 'empty', the 'rupture' type being the closest to the front. The results of the present study confirm the accepted hypothesis on calcification via extracellular matrix vesicles. It is thought that the cell secretes 'empty' vesicles that accumulate amorphous Ca and P to form a hydroxy-apatite crystal. This is followed by rupture of the vesicular membrane. The propagation of the process is accompanied by increase in the vesicular diameter and its approximation to the calcifying front.

Animals↗
PubMed1987

Extracellular matrix vesicle distribution in primary mineralization two weeks after injury to rat tibial bone (ultrastructural tissue morphometry).

Primary mineralization on the 14th day of bone healing served as a model to study the distribution of extracellular matrix vesicles by means of transmission electron microscopy combined with computerized morphometry. Vesicles were traced on electron micrographs and classified according to diameter, distance from the calcified front, and type. The different types were determined as follows: electron-lucent vesicles ("empty"), vesicles with amorphous contents ("amorphic"), vesicles containing crystalline depositions ("crystal"), and vesicles with crystals and ruptured membranes ("rupture"). The majority of the vesicles measured between 0.02 and 0.07 micron and were located at a distance of less than 3 micron from the calcified front. They were distributed according to "empty", "amorphic", "crystal" and "rupture" type in concentrations of 10%, 31%, 51% and 8%, respectively. The diameters of the "rupture" vesicles were significantly larger than those of the "empty" and "amorphic" types. The sequence of their location, starting at the calcified front, ran as follows: "rupture", "crystal", "amorphic" and "empty", with the "rupture" type proximate to the front. According to the working hypothesis on calcification via extracellular matrix vesicles, it is thought that the "empty" vesicles are secreted by the cell and that subsequently amorphous Ca and Pi accumulate intravesicularly to form a hydroxyapatite crystal which, in turn, brings about rupture of the vesicle's membrane. The results of the present study support this theory and, additionally, show that the maturation process is accompanied by an increase of the vesicular diameter and by its approximation to the calcifying front.

Animals↗
PubMed1986

Magnetic localisation of intracranial dipoles: simulation with a physical model.

Current dipoles energized by isolated sources were located in known positions inside a human skull filled with an electrically conductive medium. Maps of the measured electrical and magnetic fields confirmed the predicted relationships between those fields for both single and multiple dipoles. Two methods of dipole localisation were compared: the peak-location method which used only the locations of the maximum and minimum recorded values, and a least-squares iterative method which found the parameters for a dipole such that the sum of squared differences between the recorded and predicted data was minimized. Also, in an attempt to account for some of the error due to the non-sphericity of the head, the measured distance from the centre of the skull to each recording position was used in the dipole calculations. This last technique resulted in the smallest 3-dimensional location error (averaging 3.5 mm) for the least-squares method, even when no recording positions were near the actual field extrema and the peak-location method therefore produced much greater error. Also investigated were combinations of two dipoles for which the magnetic field maps appeared similar to those for a single dipole and comparisons were made to determine how well single and double dipole models could account for the recorded data.

Brain↗