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Biomedical subjects

M C Johnson

Publications and source records attributed to M C Johnson.

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

Cloning and sequencing of a cDNA expressing a recombinant house dust mite protein that binds human IgE and corresponds to an important low molecular weight allergen.

A cDNA clone coding for a mite allergen of mol wt approximately 14,000 has been isolated and its DNA sequence determined. The native component from mite extracts encoded by this DNA was identified by immunoprobing blots of mite body extract with human IgE eluted from the electroblotted cloned fusion polypeptides derived from the expressed cDNA clone. The clone encodes a polypeptide with a deduced mol wt of 17,460. The deduced amino acid sequence was not homologous to any known protein sequences and it contains no cysteine or tryptophan. On blots, 21 of 38 sera from mite-allergic subjects recognized the cloned material, and this recognition strongly correlated with IgE-binding to the native component on protein blots of mite extract.

Allergens↗
PubMed1989

A-69024: a non-benzazepine antagonist with selectivity for the dopamine D-1 receptor.

A-69024 HBr, 1-(2-bromo-4,5-dimethoxybenzyl)-7-hydroxy-6-methoxy-2-methyl-1,2,3,4- tetrahydroisoquinoline hydrobromide, is a selective antagonist of the dopamine D-1 receptor. A-69024 HBr shows an apparent affinity toward the D-1 receptor (identified using [125I]SCH 23390) of 12.6 (4.15-38.3) nM (mean (90% CL), n = 3); the apparent affinity toward the D-2 receptor (identified using [3H]spiroperidol is 1 290 (1,200-1,380) nM (n = 3); using [125I]lysergic acid diethylamine to identify the 5-HT1C receptor gives apparent affinity of 17,800 (9,700-32,600) nM (n = 3). In assays of adenylate cyclase activity, A-69024 HBr antagonizes the D-1 receptor with a calculated affinity of 43.9 (17.5-110) nM (n = 5), while the molecule antagonizes the D-2 receptor with a calculated affinity greater than 400 nM. Behavioral studies demonstrate that A-69024 HBr (5 mg/kg s.c.) is able to block both amphetamine-induced locomotor activity and apomorphine-induced stereotypy. Furthermore, A-69024 HBr blocks SF&F 38393-, but not quinpirole-, induced rotation in rats having unilateral 6-hydroxydopamine lesions of the substantia nigra. When administered at behaviorally effective doses. A-69024 HBr neither increases the concentration of serum prolactin nor potentiates dihydroxyphenylalanine (DOPA) accumulation in the caudate-putamen of rats pretreated with the DOPA decarboxylase inhibitor NSD 1015. Because A-69024 is a dopamine receptor antagonist discriminating between the D-1 and D-2 receptors, it may be a useful research tool.

Adenylyl Cyclases↗
PubMed1989

Immunologic consequences of acute ethanol ingestion in rats.

Acute ethanol (EtOH) intoxication is commonly associated with many medical and surgical problems which primarily or secondarily involve infection. Chronic EtOH ingestion has been associated with immune dysfunction and an increased risk of infection; however, the relationship of acute EtOH exposure and immune function has not been clearly defined. To determine if there is a relationship between acute EtOH intoxication and immune function, the effects of a single EtOH ingestion on immune function were studied in a rat model. Acute intoxication was produced by gavage feeding of 3 g/kg of EtOH, and immune function was evaluated by in vivo chemotaxis to a chemotactic peptide, N-formyl-methionyl-leucyl-phenylalanine and responsiveness of splenic lymphocytes to B- and T-cell mitogens. Chemotaxis was significantly suppressed at 4 hr (49.0 +/- 5.1% of control) after EtOH ingestion (P = 0.001), but returned to normal by 24 hr and remained at that level. However, acute EtOH ingestion showed no suppressive effects on lymphocyte responsiveness to either concanavalin A or LPS. These results indicate that a single ingestion of EtOH has the potential to transiently suppress chemotactic function of granulocytes but not affect lymphocyte mitogenic responsiveness in rats. This potential may contribute to increased susceptibility to infection in patients after EtOH ingestion.

Alcoholic Intoxication↗
PubMed1989

[Clinical use of CA-125 in gynecology. Preliminary experience].

CA-125 levels were measured in 27 normal women, 11 with benign gynecologic pathology and 13 with ovarian cancer in different stages of evolution. The analysis of data was made retrospectively. Considering a level of 65 U/ml as normal, no false positives were found. Patients with benign gynecologic pathology behave as the normal ones with no significative differences in their levels. Levels higher that 65 U/ml were always found in women with ovarian cancer. There were 4 patients with negative levels and clinically or surgically verified disease. Positive levels correlated with histologic type and with surgical staging. In patients with serial levels, decrease in tumoral volume was correlated with decrease in levels. These data suggest that the behaviour of CA-125 in our local population is the same as reported in the literature. It is useful, when is positive, in follow-up, management and prognosis of patients with ovarian cancer. Its negativity is not guarantee of cure and positive levels make evident the presence of the disease. It is a poor diagnostic method because of its low sensitivity.

Antibodies, Monoclonal↗
PubMed1989

Two-dimensional gel electrophoresis of calf aqueous humor, serum, and filter-bound proteins.

Recent studies have demonstrated that bovine and primate aqueous humor (AH) obstruct flow when perfused through artificial membranes with pore sizes similar to those found in the aqueous outflow pathway. Proteinaceous AH components were implicated in this phenomenon, which is not observed with serum diluted to comparable protein concentrations. In this study, we used two-dimensional gel electrophoresis to characterize the protein composition of calf AH and to identify those proteins binding to the filters and presumably causing this obstruction. Comparison of AH and serum under denaturing conditions showed quantitative and qualitative differences in their protein content. Among the most important: AH was seen to possess two protein subunit trains (approximately 28 kD and approximately 48 kD) not found in serum and two trains (approximately 28 kD and approximately 80 kD) with additionally charged components not found in serum. Serum, on the other hand, possesses one train (approximately 80-90 kD) not found in AH as well as a slightly greater relative amount of high-molecular weight protein subunits. The finding that hydrophobic filters retain more protein components than do hydrophilic filters suggests that the type and amount of protein adhering to them is determined largely by hydrophobic interactions. Whether such interactions occur in the outflow system, and if so, how they may relate to aqueous drainage remains to be determined.

Animals↗
PubMed1988

Purification, characterization and antimicrobial spectrum of a bacteriocin produced by Pediococcus acidilactici.

An antimicrobial peptide designated pediocin AcH was isolated from Pediococcus acidilactici strain H. The pediocin AcH was purified by ion exchange chromatography. The molecular weight of pediocin AcH was determined by SDS-PAGE to be about 2700 daltons. Pediocin AcH was sensitive to proteolytic enzymes resistant to heat and organic solvents, and active over a wide range of pH. Pediocin AcH exhibited inhibition against several food spoilage bacteria and foodborne pathogens including Staphylococcus aureus, Clostridium perfringens and Listeria monocytogenes. It was bactericidal to sensitive cells and acted very rapidly. The bactericidal effect was not produced by either cell lysis or apparent loss of membrane permeability.

Bacteria↗
PubMed1987

Selection of Lactobacillus acidophilus strains for use in "acidophilus products".

Recent studies by DNA-DNA hybridization revealed that strains now designated as L. acidophilus, can be divided into several groups and only one group should be classified as L. acidophilus. We studied several phenotypic characteristics in representative strains from the six DNA-homology groups of L. acidophilus. No group specific pattern was observed among the strains for fermentation of eight carbohydrates, growth at 15 and 45 degrees C, resistance to 0.2% oxgall, lysis by lysozyme or sensitivity to 17 antibiotics. However, some differences among groups were observed in beta-galactosidase (beta-gal) activity and surface layer (s-layer) protein. Strains in B1 do not have a s-layer or beta-gal while B2 strains also lack a s-layer but do possess beta-gal. All strains in groups A1, A2, A3 and A4, capable of growing in lactose, have beta-gal activity and also have a s-layer composed of protein subunits of different molecular weights (MW). Strains in A1 homology group have a s-layer with 46 Kd protein subunits while strains in other A groups have s-layer protein subunits that varied in MW within each group. On the basis of these two traits several isolates of unknown homology groups have been tentatively placed in A1, B1 or B2 groups. L. acidophilus from A1 group showed strain variation in beta-gal specific activity and rate of acid production and growth. For use in dietary adjuncts, L. acidophilus strains should be selected for these three and other desirable traits. They should be maintained and grown in media containing lactose.

Bacterial Outer Membrane Proteins↗
PubMed1987

Clinical indications for cervical spine radiographs in the traumatized patient.

During a 4 1/2 year period, 4,941 trauma patients were admitted to a hospital, and details of their injuries and treatment were entered in a computerized trauma registry. Using that database, patients with cervical spine injury were studied. Of the 4,941 patients, 1,823 (38 percent) had radiographs of the cervical spine. Ninety-four patients (5 percent) of these patients had injuries of the cervical spine or spinal cord. Sixty five of the 94 patients with cervical spine injury were alert. All had either neck pain or neck tenderness. We do not recommend screening cervical spine radiographs for the alert trauma patient without neck pain; however, we do recommend screening for all patients with decreased levels of consciousness and an injury that could have conceivably injured the cervical spine, for all patients with neurologic deficits compatible with a cervical origin, and for all patients with neck pain or tenderness. Lateral cervical spine radiographs were obtained in all injured patients. They demonstrated cervical spine injury in 70 patients (74 percent) and missed the injury in the remaining 24, which resulted in an unacceptable false-negative rate of 26 percent. We believe that all patients at risk for cervical spine injuries must have complete radiographic examinations of the cervical spine. Computerized axial tomography was the most useful modality to confirm a cervical spine injury in those patients whose lateral cervical spines appeared normal radiographically, especially in patients with associated head injury requiring computerized axial tomography of the brain. Computerized axial tomography diagnosed the injury in 14 of the 24 patients requiring study beyond initial screening. Also presented herein is a radiologic screening algorithm for cervical spine injuries in trauma patients.

Accidents, Traffic↗
PubMed1987

Effect of optimization of hemodynamics on fibrinolytic activity and antithrombotic efficacy of external pneumatic calf compression.

External pneumatic calf compression is effective but imperfect for antithrombotic prophylaxis in surgical patients. In preliminary studies, sequential filling of multisegmented leggings with graded pressure decreasing from ankle to knee increased venous flow velocity and wall shear stress, decreased residual venous volume, and enhanced postoperative fibrinolysis more than uniform compression. To determine if improved hemodynamics also increased antithrombotic activity, we performed a prospective randomized trial in neurosurgical patients comparing sequential application of graded pressure with uniform pressure applied to either a segmented bladder or to a single bladder. Deep vein thrombosis was diagnosed by leg scanning and impedance plethysmography and confirmed by phlebography. Venous thrombosis developed in 3 of 45 patients with graded-sequential filling, 6 of 50 with uniform compression-multiple compartments, and 3 of 41 with uniform pressure single bladder (differences not significant). These results suggest either that uniform compression offers all that can be expected of external pneumatic calf compression in prevention of venous thrombosis, or that even if a study with greater statistical power showed graded-sequential filling to be superior, the benefit/cost ratio of the more complex latter system is not likely to be large.

Adolescent↗
PubMed1987

Active tuberculosis in the medical intensive care unit: a 15-year retrospective analysis.

Of approximately 6000 admissions to the Henry Ford Hospital medical ICU between October 1969 and September 1984, 61 (1%) had active tuberculosis (TB). Forty-three (70%) of these 61 had acute respiratory failure (ARF). TB was considered to be the sole cause of ARF in 12 and contributory in 31. Eighteen patients with TB but without ARF were admitted for treatment of other critical illnesses. Alcoholism was present in 31 (51%) of the TB patients. Only one of 12 whose ARF was caused primarily by TB had a history of known TB at the time of admission. Important factors contributing to ARF in TB patients included Gram-negative pneumonia and/or sepsis, chronic obstructive pulmonary disease, prior TB with anti-TB medication noncompliance, and malignancy. Six patients were not suspected of having TB when admitted to the medical ICU; three patients who had not been treated for TB were found to have TB on autopsy. The inhospital mortality rate for all patients with TB requiring intensive care was 67%, but was 81% in those with ARF.

Female↗
PubMed1986

Transport and steady-state concentration of plasma proteins in the vitreous humor of the chicken embryo: implications for the mechanism of eye growth during early development.

The nature and origin of the proteins of the vitreous humor were examined in chickens during embryonic and early posthatching stages. The major proteins of the vitreous humor were similar in electrophoretic mobility to plasma proteins at all ages examined. Earlier studies from our laboratory and experiments described below showed that plasma proteins continuously entered and left the eye throughout its development. From these data it was concluded that the majority of vitreous-humor proteins were derived from the blood. The protein concentration of the vitreous humor was 13% of that of the plasma from embryonic Days 6 through 15 (E6 through E15). After E15, the relative protein concentration in the vitreous humor declined with respect to the plasma and reached 4% of the plasma protein concentration at hatching. Several possibilities were considered to account for how proteins can rapidly enter and leave the eye, yet maintain a steady-state concentration in the vitreous humor that is less than one-seventh of that in the blood.

Animals↗
PubMed1986

Penetrating atherosclerotic ulcers of the thoracic aorta: natural history and clinicopathologic correlations.

Clinically, penetrating atheromatous ulceration of the aortic wall may be confused with either symptomatic thoracic aneurysm or classic spontaneous aortic dissection. Aortography and computed tomographic (CT) scanning of the thoracic aorta provide specific diagnostic information which permits one to distinguish this lesion from atherosclerotic aneurysm and classic dissection. Hallmarks of findings on aortography and CT scan include the presence of the ulcer and an intramural hematoma. Since the findings may be disarmingly subtle, the potentially progressive and serious nature of this condition may remain unappreciated. Recognition of the penetrating atheromatous ulcer and distinguishing it from aortic dissection arising just distal to the origin of the left subclavian artery is mandatory. Resection of only a conservative segment of the proximal descending aorta suffices for classic dissection in the upper descending thoracic aorta, but the penetrating aortic ulcer requires graft replacement in the area of the ulcer and intramural hematoma.

Aged↗
PubMed1986

Anatomical basis for repair of ulnar and median nerves in the distal part of the forearm by group fascicular suture and nerve-grafting.

The topography of the intraneural fascicular groups must be understood if the treatment of acute lacerations of the major nerves in the forearm is to be successful. Most lacerations in the upper extremity occur at the wrist and in the distal half of the forearm. With microsurgical longitudinal dissections and serial sections, we studied the intraneural topography of the fascicular groups of the median and ulnar nerves utilizing forty-five fresh frozen or refrigerated specimens. We devised a new technique of light photography to demonstrate the distinct boundaries of the fascicular groups. The intraneural fascicular groups provide the anatomical basis for the recommended surgical techniques of group fascicular repair and nerve-grafting.

Cadaver↗
PubMed1986

Calculations of flow resistance in the juxtacanalicular meshwork.

The structure of the juxtacanalicular meshwork (JCM) was analyzed morphometrically, and the resulting data were used to calculate the resistance to flow through this tissue. Two models of the JCM were presented and compared. In the first (Model A), aqueous humor was assumed to flow via open channels within a solid framework, while, in the second (Model B), these open spaces were assumed to be filled with extracellular matrix gel. An expression giving the resistance of such a gel as a function of gel concentration was presented and tested on corneal and scleral stroma. Morphometry of normal and glaucomatous human eyes showed that Model A underpredicted the resistance of the JCM by factors of 10-100, suggesting that a GAG or proteoglycan gel may control the flow resistance of this tissue. This was supported by Model B, which showed that measured bulk concentrations of GAGs were consistent with gel concentrations needed to account for the estimated resistance of the JCM in vivo. Some limitations and implications of Model B were discussed.

Aqueous Humor↗
PubMed1985

Surgical significance of the motor fascicular group of the ulnar nerve in the forearm.

The topography of the fascicular group of the ulnar nerve at the wrist and forearm was studied focusing on the motor (muscle) fascicular group. In 109 of 111 specimens studied (98%), the motor fascicular group of the ulnar nerve is located at the ulnar dorsal or straight dorsal position at the wrist and the distal forearm. This motor fascicular group may be identified as a distinct entity up to 90 mm proximal from the level of the radial styloid. The relatively constant location of the motor fascicular group is significant since most lacerations of the major peripheral nerves of the upper extremity are at the distal forearm or the wrist. In the surgical treatment of acute lacerations of the ulnar nerve at these levels, one should direct special attention to the correct identification, matching, and alignment of the motor fascicular group to enhance reinnervation of the intrinsic muscles of the hand.

Forearm↗
PubMed1985

Insect feeding deterrents in endophyte-infected tall fescue.

The presence of an endophytic fungus, Acremonium coenophialum, in tall fescue (Festuca arundinacea) deterred aphid feeding by Rhopalosiphum padi and Schizaphis graminum. Both species of aphid were unable to survive when confined to endophyte-infected tall fescue plants. Feeding deterrents and toxic factors to R. padi and Oncopeltus fasciatus, large milkweed bug, were primarily associated with a methanol extract obtained when endophyte-infected tall fescue seed was serially extracted with hexane, ethyl acetate, and methanol. The concentrations of pyrrolizidine alkaloids were determined to be 30 to 100 times greater in the methanol extract than in the hexane and ethyl acetate extracts.

Journal Article↗