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Biomedical subjects

R S Smith

Publications and source records attributed to R S Smith.

At least 163 records · Page 9Linked to original sources
PubMed1988

Localization of two epitopes of apolipoprotein A-I that are exposed on human high density lipoproteins using monoclonal antibodies and synthetic peptides.

To understand the structure of apolipoprotein A-I, we have used an immunochemical approach and identified specific regions of apoA-I that may be exposed on the apoprotein as it exists on high density lipoprotein (HDL). Twelve mouse monoclonal antibodies specific for human apoA-I were generated from six fusions. Thirteen synthetic peptides of between 5 and 16 amino acid residues in length, which span the amino-terminal two-thirds of apoA-I, were tested for their ability to react with each of the 12 antibodies. In a competitive solid-phase radioimmunoassay, a synthetic peptide, which represented residues 1-15 of mature apoA-I, inhibited the binding of antibody AI-16 to immobilized HDL. Similarly, a synthetic peptide, which represented residues 90-105 of apoA-I, inhibited the binding of antibody AI-18 to immobilized HDL. Using systematic changes in the size and sequence of the oligopeptides, the limits and essential amino acid residues of these epitopes were defined. Comparisons of the slopes of the competition curves obtained with immunoreactive peptides, isolated apoA-I, and HDL verified that these two regions of apoA-I are exposed on the surface of apoA-I as it exists on native HDL.

Animals↗
PubMed1988

Organelle dynamics in lobster axons: anterograde and retrograde particulate organelles.

Particulate organelles in isolated axons from the walking legs of the lobster were detected with differential interference contrast optics and video microscopic techniques. The motion of the organelles was studied in normal axons, in axons whose surface membrane was rendered permeable with saponin, and in axoplasm extruded from the axons. In normal axons at 20-22 degrees C, organelles moved more rapidly in the anterograde direction than in the retrograde direction (respective mean velocities 1.73 micron/s and 0.63 micron/s). The instantaneous velocities of both sets of organelles were variable: those of the anterograde organelles varied less than those of retrograde organelles. The variation in instantaneous velocity was patterned; all organelles studied had velocities that fluctuated slowly with a major frequency at about 0.1 Hz. Some organelles oscillated about a fixed position at a similar major frequency. In axons with a permeabilized surface membrane there was no organelle motion unless adenosine 5'-triphosphate (ATP) was present in the bathing medium. Organelle motion reactivated with ATP was patterned in a way similar to that in normal intact axons. In extruded axoplasm in the presence of ATP, organelles moved along transport filaments that were assumed to be microtubules. Movement of organelles from one transport filament to another was not accompanied by changes in motion that could explain the normal fluctuation in velocity. The evidence indicates that the variable, or oscillatory, character of organelle motion in lobster axons is caused by an active component of the mechanisms of axonal transport.

Animals↗
PubMed1988

Studies on the mechanism of the reversal of rapid organelle transport in myelinated axons of Xenopus laevis.

Rapid organelle transport was studied by computer- and video-enhanced microscopy in the region of localized lesions in single myelinated axons of Xenopus laevis. Localized lesions were created that were either impermeable to small ions in the bathing medium or were permeable to agents with molecular weights up to 10,000. Providing the axons were bathed in a suitable "internal" medium, organelle transport continued to within a few micrometers of the lesion whether the lesion was permeable or not. Organelles undergoing anterograde and retrograde transport reversed their direction of transport on reaching the lesion. In preparations with lesions that were permeable, nonhydrolyzable analogs of ATP inhibited normally directed and reversed organelle transport. In permeable preparations, vanadate and EDTA inhibited retrograde and reversed retrograde transport at different intra-axonal concentrations; anterograde and reversed anterograde transport were also differentially inhibited. Anterograde and retrograde organelle transport were also shown to be inhibited at different intraaxonal concentrations of vanadate and EDTA. The results provide evidence for the existence of two different axonal transport mechanisms in myelinated axons. The two mechanisms can account for the normally directed and reversed transport of individual organelles.

Animals↗
PubMed1988

Osteochondrosis of the fourth metacarpal head after closed trauma.

A rare case of osteochondrosis of the fourth metacarpal head after blunt trauma to the hand is presented. Follow-up at 2 years showed mild residual deformity both clinically and radiographically, but the child was asymptomatic. The cause of this condition is unknown, but it appears to be one of the few osteochondroses related to a single episode of direct trauma.

Child↗
PubMed1988

Open reduction and internal fixation of volar lip fractures of the distal radius.

Fractures of the volar lip of the distal radius are relatively uncommon injuries. However, controversy exists concerning the treatment of these fractures. We reviewed our experience with open reduction and internal fixation through a volar approach using buttress plates. Sixteen patients with 17 fractures were treated by this method. Their ages ranged from 16 to 65 years (average 38 years). Eight fractures occurred secondary to motor vehicle accidents, while the remaining patients sustained falls. Mean follow-up time was 19.5 months. All fractures healed with no infections. Sixteen of the fractures were treated primarily with open reduction and internal fixation, while one patient was treated 6 weeks after injury for a malunion. Ranges of motion averaged 71 degrees dorsiflexion, 60 degrees palmar flexion, 79 degrees pronation, 78 degrees supination, 22 degrees radial deviation, and 32 degrees ulnar deviation. Analysis of results demonstrated 12 excellent, 2 good, and 3 fair results. Two patients with fair results had nonanatomic restoration of the joint surface at surgery, while the other patient with a fair result was treated late. We recommend early open reduction and internal fixation of displaced or unstable volar lip fractures of the distal radius. Accurate anatomic alignment and stable fixation are achieved with the volar buttress plate. Motion can begin 2-3 days after surgery to aid in obtaining excellent functional results.

Adult↗
PubMed1988

Detection of a protein-acetaldehyde adduct in the liver of rats fed alcohol chronically.

We report here the formation in vivo of a protein-acetaldehyde adduct (protein-AA) in liver when rats were fed alcohol chronically. This chemically modified protein was demonstrated by electroimmunotransblot technique and with rabbit polyclonal antibodies that recognize acetaldehyde adduct as an epitope (i.e., both anti-hemocyanin-AA IgG and anti-myoglobin-AA IgG). It has a molecular weight of 37,000. It can be detected in the liver of rats fed the alcohol-containing American Institute of Nutrition 1976 liquid diet for only 1 wk. Since the protein profiles of soluble hepatic proteins from alcohol-fed and control rats were identical on SDS-PAGE, the peroxidase-positive band demonstrated by electroimmunotransblot was most likely not a new protein synthesized de novo. Borohydride reduction was not necessary to stabilize this protein-AA. Intraperitoneal injections of ethanol (2 g/kg body wt) at 8-h intervals to rats over a 24-h period did not produce any detectable protein-AA in the liver. Incubation of the liver homogenate from a control liver with acetaldehyde without sodium cyanoborohydride for 4 h also failed to generate any protein-AA. Therefore, the formation of the 37-kD protein-AA in vivo reported here is dependent on chronic alcohol consumption.

Acetaldehyde↗
PubMed1988

Quantitation of plasma apolipoprotein A-I using two monoclonal antibodies in an enzyme-linked immunosorbent assay.

A rapid sandwich enzyme-linked immunosorbent assay (ELISA) for the quantitation of human apolipoprotein (apo) A-I was developed. The assay uses a pair of noncompeting purified monoclonal antibodies to detect apoA-I in plasma. The antibodies used in this assay were selected because they bind greater than 90% of radioiodinated high density lipoprotein (HDL), they identify "fresh" nondeamidated epitopes on apoA-I, and they have comparable binding affinities for isolated HDL and HDL in plasma. The assay was standardized with a plasma secondary standard composed of lyophilized human serum. The assay was used to measure the apoA-I levels in normal subjects, patients with coronary artery disease, and patients with familial hypercholesterolemia. The results indicate that certain monoclonal antibodies can be used to reliably measure plasma levels of apoA-I in diverse groups of subjects.

Antibodies, Monoclonal↗
PubMed1987

Organelle dynamics in lobster axons: anterograde, retrograde and stationary mitochondria.

Mitochondria in isolated motor axons from the walking legs of lobster were observed with differential interference contrast optics and video microscopic techniques. Movements of the mitochondria were analyzed in time-lapse videotape records. The mean velocity of transport in the retrograde direction (1.33 +/- 0.64 micron/s) was greater than the mean velocity of transport in the anterograde direction (0.72 +/- 0.26 micron/s). The mean lengths of the mitochondria moving in the retrograde and anterograde directions were only slightly different (6.9 microns and 5.5 microns, respectively). No correlation was found between mitochondrial length and average velocity or reciprocal velocity. The instantaneous velocities of mitochondria were distributed over a range of approximately 3 micron/s; both the anterograde and retrograde distributions contained a small proportion of values whose sign was opposite to the modal value. The variation in instantaneous velocity took place at frequencies close to 0.1 Hz. Some mitochondria displayed longitudinally oriented oscillatory movements of a similar low frequency. While the movement of most mitochondria was parallel to the axis of the axon, transverse deviations and complex circular paths were sometimes observed. Some mitochondria reversed their orientation and continued in the same direction, so that the end which had been the leading end became the trailing end. Many mitochondria immediately beneath the plasma membrane were stationary and adhered strongly to the plasma membrane when the axoplasmic structure was disrupted. In electron micrographs, fine strands connected peripheral mitochondria and the plasma membrane. These strands may anchor the stationary mitochondria to the plasma membrane.

Animals↗
PubMed1987

Closed interlocking nailing of the femur complicated by an intramedullary calcified lesion.

The interlocking intramedullary nail has greatly expanded the indications for closed intramedullary nailing of the femur. We describe a complication caused by the presence of a calcified lesion located at the proximal metaphyseal-diaphyseal junction of the femur. This lesion could not be penetrated by hand reamers. We used a long 3.5-mm drill bit to place a hole in the infarct, which then allowed passage of the hand reamer. The operation then proceeded in the standard fashion without complications.

Adult↗
PubMed1987

Antibody to a synthetic oligopeptide in subjects at risk for human immunodeficiency virus infection.

Detection of antibodies to human immunodeficiency virus (HIV) by enzyme-linked immunosorbent assay (ELISA) is the accepted method to screen blood products at risk to transmit infection. The presence of antibodies to HIV in 565 serum specimens from 274 patients with acquired immunodeficiency syndrome (AIDS) or AIDS-related complex, symptomatic and asymptomatic subjects at risk for AIDS, and controls was determined with an ELISA that incorporates synthetic peptides (designated E32/E34) representing sequences in the envelope glycoprotein gp41. Of 105 specimens from patients with AIDS or AIDS-related complex, 3 specimens that were negative by commercially licensed ELISA and immunoblot test were similarly unreactive in the E32/E34 ELISA. For homosexual men with generalized lymphadenopathy, 186 specimens were positive by the E32/E34 ELISA and 63 specimens were negative. In comparison, with the licensed ELISA, 184 of these samples were positive and 65 samples were negative. The two samples that were positive in the E32/E34 ELISA but not the commercial kit were also positive by immunoblotting. Sequential sera from one individual who apparently underwent seroconversion according to the commercial assays were all positive by E32/E34 ELISA and immunoblotting. Thus, the ELISA with synthetic peptides is an extremely sensitive and specific test of antibody response to HIV and has not yet yielded a negative result with a Western blot (immunoblot)-confirmed antibody-positive serum.

AIDS-Related Complex↗
PubMed1987

Structural relationship of human apolipoprotein B48 to apolipoprotein B100.

Although the complete amino acid sequence of human apolipoprotein (apo) B100 is known (4536 amino acids), the structure of apo B48 has not been defined. The objective of our study was to define the structure of apo B48 and its relationship to apo B100. Antibodies were produced against 22 synthetic peptides corresponding to sequences in human apo B100. The levels of immunoreactivity of the antipeptides to apo B100 and apo B48 were used to define the structural relationship between these two species of apo B. Six antibodies from sequences in the amino-terminal half of apo B100, including antipeptide 2110-2129, bound to both apo B100 and apo B48. 15 other apo B-specific antipeptides from sequences carboxyl-terminal to residue 2152 bound to apo B100, but not to apo B48. Immunoblots of cyanogen bromide digests of apo B100 and apo B48 with antipeptides 2068-2091 and 2110-2129 detected a 16-KD fragment (residues 2016-2151) in the apo B100 digest and a fragment of identical size in the apo B48 digest. Because apo B48 appears to contain the apo B100 cyanogen bromide fragment 2016-2151 and because an antiserum specific for the peptide 2152-2168 does not bind to apo B48, we conclude that apo B48 represents the amino-terminal 47% of apo B100 and that the carboxyl terminus of apo B48 is in the vicinity of residue 2151 of apo B100.

Amino Acids↗
PubMed1987

External fixation of open comminuted fractures of the proximal phalanx.

External fixation is an accepted method of treatment for many injuries, however, only a limited number of reports concern its use in open, comminuted fractures of the hand. Ten patients with eleven fractures of the proximal phalanx were treated using the AO/ASIF small external fixator. Five fractures involved the interphalangeal joint (IPJ), two the metacarpophalangeal joint (MPJ), and four the shaft. Nine fractures were caused by small caliber gunshot wounds, one was due to a power saw injury, and one occurred during a three wheeler accident. The patients with interphalangeal joint involvement all had extensive involvement of one or both of the joint surfaces. The fixator was placed across the joint and a stable ankylosis allowed to occur with the IPJ in 30 degrees to 40 degrees of flexion. MPJ motion averaged 75 degrees in these patients while distal interphalangeal joint (DIPJ) motion averaged 20 degrees. The four patients with shaft fractures all healed, but three required bone grafting. These patients averaged 85 degrees of MPJ motion, 25 degrees of proximal interphalangeal joint (PIPJ) motion, and 30 degrees of DIPJ motion. One patient with metacarpophalangeal joint involvement regained 85 degrees of MPJ motion but had limited motion at the PIPJ and DIPJ. The other patient with MPJ involvement suffered massive bone loss; a ray amputation was eventually performed. Complications included pin tract drainage in three of the eleven fractures and slight loss of reduction in two fractures. The best clinical results occurred when the fixator was used as a digit salvage procedure in interphalangeal joint fractures.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1986

Spontaneous resolution of herpes simplex blepharoconjunctivitis in children.

We observed three children, aged 1 year 8 months to 9 years 7 months, in whom herpes simplex blepharoconjunctivitis resolved promptly without treatment. A fourth child, 8 years old, developed probable toxic manifestations from topical vidarabine. These manifestations, as well as the blepharoconjunctivitis, resolved when the medication was discontinued. Herpes simplex ocular infection without corneal involvement in children is usually benign and self-limited.

Child↗
PubMed1986

Traumatic rupture of the aorta: still a lethal injury.

A 10 year retrospective review of a community experience with blunt trauma of the aorta has been presented. We found that an overall mortality of 84 percent was associated with this injury. Fourteen patients reached the emergency department with stable vital signs. Of these patients, 10 underwent successful treatment (71 percent). Despite advances in many areas of trauma care, blunt trauma of the aorta remains a highly lethal injury. However, this review has demonstrated that with prompt diagnosis and treatment, a significant number of these patients can be salvaged. It is for this reason that we have adopted an aggressive approach toward victims of blunt trauma. We now proceed with diagnostic aortography in any patient who has undergone a significant deceleration injury.

Accidents, Traffic↗