Showing papers by "Georgetown University published in 1970"
TL;DR: The results demonstrate the absence of intracellular membranes and suggest that the outer membrane of the platelet is similar to plasma membranes of other cells, and they provide biochemical confirmation of its origin from the plasma membrane ofThe megakaryocyte.
393 citations
TL;DR: The occurrence of metastasis of maternal cancer to the products of conception is numerically inconsequential but offers an opportunity for significant biological research into the behavior of cancer.
Abstract: The occurrence of metastasis of maternal cancer to the products of conception is numerically inconsequential but offers an opportunity for significant biological research into the behavior of cancer. More extensive investigation, both clinical and experimental, is necessary before any firm conclusions can be established. The surprisingly infrequent occurrence of this condition allows speculation that biological protective mechanisms may exist for the placentofetal unit. Circulatory or immunologic responses may play a role in this defense. The possibility of an intrinsic trophoblastic property achieving this result warrants investigation.
197 citations
TL;DR: The etiological agents of bacillary necrosis, a disease of larval and juvenile bivalve mollusks, are designated members of the genus Vibrio.
Abstract: The etiological agents of bacillary necrosis, a disease of larval and juvenile bivalve mollusks, are designated members of the genus Vibrio.
144 citations
TL;DR: It is suggested that in addition to elaborating steriod hormones, corpora lutea may also secrete a proteinaceous product, perhaps relaxin, which is related to the high titers of serum gonadotrophin (s) during early gestation.
Abstract: The fine structure of granulosa lutein cells and theca lutein cells of human corpora lutea of early pregnancy and during the progestational phase of the menstrual cycle (i.e., 1 day, 7 days and 9 days after estimated ovulation) is described. Granulosa lutein cells of early pregnancy are distinguished from theca lutein cells in having: (1) a more homogeneous, electron-lucent nuclear matrix, (2) enlarged pleomorphic mitochondria with irregularly-shaped, osmiophilic inclusions, (3) numerous isolated regions of the Golgi complex, (4) abundant whorls of granular and agranular endoplasmic reticulum, (5) a folded-membrane complex, (6) numerous bundles of 50 A filaments and (7) patches of elongated microvilli bordering intercellular and intracellular canaliculi.
Furthermore, granulosa lutein cells of early pregnancy are distinguished from granulosa lutein cells of corpora taken during the progestational stage of the menstrual cycle by the greater abundance of granular and agranular endoplasmic reticulum, the presence of concentric membranous whorls and large spherical mitochondria, increases in membrane-bound granules and a more extensive development of intracellular canaliculi. These differences are related to the high titers of serum gonadotrophin (s) during early gestation.
The morphology of human corpora lutea is compared with steroidogenic tissues of other species and is correlated with the capacity of human corpora lutea to synthesize estrogens in addition to progestogens. Based upon morphological evidence, it is suggested that in addition to elaborating steriod hormones, corpora lutea may also secrete a proteinaceous product, perhaps relaxin.1
104 citations
97 citations
TL;DR: Studies presented here suggest that the microtubular structures are not specifically related to myxoviruses, but occur in a variety of human diseases and experimental viral infections.
92 citations
TL;DR: The molecular nature of R-factor deoxyribonucleic acid (DNA) was examined in Escherichia coli by using a method for the specific labeling of the derepressed R factor, R1, in a female cell after conjugation.
Abstract: The molecular nature of R-factor deoxyribonucleic acid (DNA) was examined in Escherichia coli by using a method for the specific labeling of the derepressed R factor, R1, in a female cell after conjugation. Sixty minutes after mating, the R factor was isolated as a single molecule with a molecular weight of 65 × 106 daltons. This single molecular species sedimented as either a covalently closed molecule or a “nicked” circle. When the single R-factor component was centrifuged in a CsCl density gradient, only a single homogeneous species with a buoyant density of 1.711 g/cm3 was observed. R-factor DNA was also isolated directly from exponentially growing cells of E. coli as a covalently closed single molecular species comprising about 1% of the total cellular DNA. Previous studies in Proteus show that R1 factor DNA components of buoyant density 1.709, 1.711, and 1.716 g/cm3 can be identified as distinct replicons. It is suggested that the single molecule of R1 observed in E. coli is most simply explained as a composite structure resulting from a recombinational assemblage of a 1.709 and 1.716 g/cm3 replicon.
80 citations
75 citations
TL;DR: The Boren (1963) technique for studying variables affecting acquisition with an individual-S design was modified and used with pigeons as mentioned in this paper, and the sensitivity and reversibility of the steady-state baseline were demonstrated by temporarily removing the different Stimuli correlated with the different members of the chain.
Abstract: The Boren (1963) technique for studying variables affecting acquisition with an individual-S design was modified and used with pigeons. The sensitivity and reversibility of the steady-state baseline were demonstrated by temporarily removing the different Stimuli correlated with the different members of the chain. This “tandem” probe produced a substantial increase in the number of learning errors.
58 citations
56 citations
TL;DR: A new method of treatment for recurrent dorsal dislocated of the first carpometacarpal joint by means of a simple volar translocation of the abductor pollicis longus tendon is described, with a satisfactory long-term result.
Abstract: A new method of treatment for recurrent dorsal dislocation of the first carpometacarpal joint by means of a simple volar translocation of the abductor pollicis longus tendon is described, with a satisfactory long-term result.
TL;DR: The finding of a functional abnormality in an X-linked enzyme is consonant with the known X- linked recessive mode of transmission of this form of the entity, and may provide a basis for the study of other abnormalities of the leukocyte, the socalled neutrophil dysfunction syndrome.
Abstract: Extract: Glucose 6-phosphate dehydrogenase (EG. 1.1.1.49) (Glc-6-PD) activity was measured in the lcukocytes and red cells of three patients with the classic form of chronic granulomatous discase (CGD) and in controls. Leukocyte homogenates from all three children revealed a decreased Glc-6-PD activity. The activities in both white cells and red cells, measured at timed intervals under conditions of storage at 0° or heating at 38° revealed a more rapid rate of decay in cells of patients than that seen in cells of control subjects. Studies measuring the activities of Glc-6-PD in the presence of 10 μM NADP, or 14 mM 2-mercaptoethanol, or both, disclosed a stabilizing effect with these reagents. Measurement of activity of another NADP-dependent enzyme, 6-phosphogluconic dehydrogenase (EC. 1.1.1.43) (6-PGD), in leukocytes were within normal limits. A correlation coefficient of 0.86 (P < 0.01) was found between Glc-6-Pd activity and the quantitative nitrobluc tetrazolium (NBT) test used to diagnose CGD. Speculation: An increased rate of decay in activity of glucose 6-phosphate dehydrogenase was detected in the leukocytes and red cells of patients with one form of chronic granulomatous disease. The finding of a functional abnormality in an X-linked enzyme is consonant with the known X-linked recessive mode of transmission of this form of the entity. The metabolic derangement involving leukocyte Glc-6-PD activity may provide a basis for the study of other abnormalities of the leukocyte, the socalled neutrophil dysfunction syndrome [7].
TL;DR: Fluids from 3 subjects with atypical features of SLE were exudates that contained increased concentrations of proteins and complement, thus similar to rheumatoid effusions, but lacking the polymorphonuclear leukocytosis and r heumatoid factor found in RA.
Abstract: Synovial fluids from 26 patients with SLE were usually clear and viscous, with few WBCs and low complement. Twelve fluids, studied in detail, were further characterized according to protein and IgG concentrations. Four were transudates. Fluids from 3 subjects with atypical features of SLE were exudates that contained increased concentrations of proteins and complement. Five other fluids were exudates with very low complement, thus similar to rheumatoid effusions, but lacking the polymorphonuclear leukocytosis and rheumatoid factor found in RA.
TL;DR: The behavior of lambda in Salmonella hybrids was the absence of zygotic induction of the prophage when transferred from E. coli K-12 donors to S. typhosa hybrids, and a new lambda mutant class, capable of forming plaques on S. Typhosa hybrids refractory to wild-type lambda, was isolated at low frequency.
Abstract: Salmonella typhosa hybrids able to adsorb lambda were obtained by mating S. typhosa recipients with Escherichia coli K-12 donors. After adsorption of wild-type λ to these S. typhosa hybrids, no plaques or infective centers could be detected. E. coli K-12 gal+ genes carried by the defective phage λdg were transduced to S. typhosa hybrids with HFT lysates derived from E. coli heterogenotes. The lysogenic state which resulted in the S. typhosa hybrids after gal+ transduction differed from that of E. coli. Ability to produce λ, initially present, was permanently segregated by transductants of the S. typhosa hybrid. S. typhosa lysogens did not lyse upon treatment for phage induction with mitomycin C, ultraviolet light, or heat in the case of thermoinducible λ. A further difference in the behavior of λ in Salmonella hybrids was the absence of zygotic induction of the prophage when transferred from E. coli K-12 donors to S. typhosa. A new λ mutant class, capable of forming plaques on S. typhosa hybrids refractory to wild-type λ, was isolated at low frequency by plating λ on S. typhosa hybrid WR4254. Such mutants have been designated as λsx, and a mutant allele of λsx was located between the P and Q genes of the λ chromosome. Plaques were formed also on the S. typhosa hybrid host with a series of λi21 hybrid phages which contain the N gene of phage 21. The significance of these results in terms of Salmonella species as hosts for λ is discussed.
TL;DR: Absence of pulmonary artery flow to one lung with maintenance of relatively normal ventilation limits the broad range of diagnostic possibilities to three entities: pulmonary artery agenesis, thrombotic occlusion, and branch stenosis.
Abstract: Pulmonary artery agenesis is one of several diagnostic possibilities which may present with similar chest roentgenographic features, including unilateral pulmonary hypoperfusion and nonvisualization of a pulmonary artery. We have applied ventilation and perfusion scintiphotography as an aid in differentiating agenesis from the other conditions with which it may be confused. Four patients presenting with the chest roentgenographic features suggestive of pulmonary artery agenesis were evaluated, when possible, with complete pulmonary function studies, bronchography, cardiac catheterization, and pulmonary and aortic angiography. In all patients, the distribution of ventilation and perfusion were evaluated with the Anger scintillation camera, 133xenon being used for the ventilation study and 131I-MAA for the perfusion study. In each patient, perfusion scintiphotography showed no blood flow to the affected lung, while ventilation scintiphotography disclosed preservation of homogeneous ventilation to that lung....
TL;DR: Although causing a diversity of findings, myocardial disease may be sufficiently characteristic to justify clinical diagnosis, the evolution of electrocardiographic changes has important prognostic significance.
TL;DR: The hypothesis that the single species of R-factor DNA observed in E. coli represents a composite of the 1.709 and 1.716 g/cm(3) replicons seen in Proteus is supported.
Abstract: A variant of the derepressed R factor, R1, which does not contain any of the drug resistance markers, and represents, in large part, the resistance transfer factor (RTF) was studied in Escherichia coli. RTF deoxyribonucleic acid (DNA) was specifically labeled in a female cell after conjugation. Physical characterization of the molecule showed that RTF possessed an average molecular weight of 50 × 106 daltons and a buoyant density of 1.709 g/cm3. By comparison to R1, we calculate that the region of DNA carrying the drug resistance genes is therefore about 20% of the R1 molecule and has a buoyant density of approximately 1.716 g/cm3. These results support the hypothesis that the single species of R-factor DNA observed in E. coli represents a composite of the 1.709 and 1.716 g/cm3 replicons seen in Proteus.
TL;DR: It is concluded that shock is associated with preferential diversion of blood flow away from the renal bed, and plasma volume expansion and vasoactive drug therapy may improve perfusion, renal hypoperfusion often persists.
Abstract: Renal blood flow was measured by the indicator-dilution technic in 17 patients with shock related to sepsis, myocardial infarction, pulmonary embolism, or pancreatitis. Renal blood flow averaged 225 ml/min/kidney, the renal plasma transit time was prolonged to an average of nearly three times normal, and the renal fraction of cardiac output was reduced to an average of 10.6%. A direct relationship between renal vascular resistance and systematic nonrenal vascular resistance suggested that renal vasocontriction was a manifestation of a more generalized vasoconstrictor process. Since rapid infusion of dextran in patients with normal central venous pressure relaxed renal vasoconstriction and tended to increase the renal fraction, inadequate venous return apparently is an important factor in the reduced renal blood flow in shock.None of the vasoactive drugs used were effective in restoring normal renal perfusion. The vasoconstrictor drugs (norepinephrine, metaraminol, and angiotensin) increased arterial pressure and renal vascular resistance without significantly altering renal blood flow. Isoproterenol and dopamine increased renal blood flow by an average of 26%, but the renal fraction of cardiac output often decreased further. Renal blood flow was increased by an average of 67% during renal arterial infusion of acetylcholine or hydralazine.It is concluded that shock is associated with preferential diversion of blood flow away from the renal bed. Although plasma volume expansion and vasoactive drug therapy may improve perfusion, renal hypoperfusion often persists.
TL;DR: The results indicate that association of viral RNA with cellular membranes may represent an early step occurring during the replication of Sindbis virus RNA.
Abstract: Membranes from cells infected with Sindbis virus had associated with them viral ribonucleic acid (RNA) polymerase and about 60 to 70% of the viral RNA labeled when short pulses were used. This RNA contained most of the replicative intermediate and replicative form of viral RNA found in the infected cells. The use of “Mg2+ sarkosyl crystals” permitted the isolation of membrane-bound nucleic acids and allowed the demonstration that Sindbis virus RNA was synthesized on a membrane-viral RNA complex. Viral RNA from the infecting virions first became associated with the membranes during the latent period and, subsequently, slowly detached. The attachment of the viral RNA to the membranes did not require active viral RNA polymerase, since RNA from ts6, an RNA− temperature-sensitive mutant of Sindbis virus, associated with cellular membranes at a nonpermissive temperature. However, the subsequent detachment of the RNA from the membranes was restricted in the absence of viral RNA synthesis. The results indicate that association of viral RNA with cellular membranes may represent an early step occurring during the replication of Sindbis virus RNA.
TL;DR: It is suggested that immediately after upright leg exercise the blood pressure is more sensitive to mild degrees of adrenergic blockade than when patients are in the resting standing position and that the postexercise blood pressure may serve as a more reliable guide to adjustment of the dose of sympathetic blocking agents in patients with hypertension.
Abstract: Blood pressure measured immediately after a brief period of upright leg exercise was considerably lower than the resting standing blood pressure in 38 hypertensive patients treated with guanethidine or debrisoquin. The hemodynamic mechanism of this hypotension after exercise was studied in 6 hypertensive patients given guanethidine intravenously and in 16 patients treated with effective oral doses of guanethidine or debrisoquin. Intravenous and oral drug treatment blocked the reflex forearm vasoconstriction that normally occurs during leg exercise. Although supine exercise was associated with a modest fall in arterial pressure from hypertensive levels, the most dramatic effects of the blocking agents on the response to exercise were observed when patients were in the upright position. Blood pressure rose from normal to above normal levels during exercise and fell promptly to below resting levels when leg movement was stopped. Upright leg exercise in the treated patients was accompanied by a large increase in cardiac output and a sharp fall in leg volume. Immediately after exercise, cardiac output fell moderately and leg volume rapidly increased. These studies suggest that alterations in the hemodynamic response to exercise induced by sympathetic blocking agents are due both to inhibition of reflex arteriolar constriction and to large passive shifts in blood volume that occur in the upright position as a result of blockade of venous reflex adjustments. Hypotensive symptoms related to exertion probably result from the combined effects of gravitational pooling after exercise and a persistently low peripheral vascular resistance. These symptoms can promptly be corrected by reinstitution of leg exercise. It is suggested (1) that immediately after upright leg exercise the blood pressure is more sensitive to mild degrees of adrenergic blockade than when patients are in the resting standing position and (2) that the postexercise blood pressure may serve as a more reliable guide to adjustment of the dose of sympathetic blocking agents in patients with hypertension.
TL;DR: This study confirms the difficulties concerning the correct interpretation of the significance of loss of anteriorly directed forces in the presence of LVH, but the error rate in diagnosis can be considerably reduced by the use of criteria proposed on the basis of this investigation.
Abstract: Electrocardiograms recorded from patients with uncomplicated left ventricular hypertrophy (LVH) often show loss of initial anteriorly directed QRS forces. An attempt was made to differentiate these records from electrocardiograms showing a similar pattern as a result of anterior myocardial infarction (MI). Orthogonal ECGs (Frank system) obtained from 103 patients with LVH were compared to ECG obtained from 327 patients with MI. The ECG were selected on the basis of absence of Q waves in lead Z which in the conventional ECG corresponds to absence of the R wave in right precordial leads. With two simple scalar measurements, namely R amplitude in lead X ≥ 1.2 mv and the sum of amplitudes of R in leads X and Z ≥ 2.5 mv, 66% of LVH cases were recognized. With these criteria, 88% of the MI records were also correctly classified. The same measurements identified 59% of an independent sample of 66 cases of LVH with no Q in lead Z. By utilizing linear discriminant function analysis, 75% of the cases of LVH, 80% of...
TL;DR: Results indicate good penetration of clindamycin into the synovial space which appears to be independent of local inflammation.
Abstract: The new antibiotic, clindamycin, was administered to 15 patients with joint effusions. Synovial fluid samples obtained at various intervals were analyzed for clindamycin. Results indicate good penetration of clindamycin into the synovial space which appears to be independent of local inflammation.
TL;DR: The results of two studies indicated that infant vocalizations can be conditioned by using only one or two elements of the traditionally employed composite social reinforcer, consisting of auditory, tactile, and visual stimuli.
Abstract: The results of two studies indicated that infant vocalizations can be conditioned by using only one or two elements of the traditionally employed composite social reinforcer, consisting of auditory, tactile, and visual stimuli. It was also found that the components, both singly and in pairs, are of relatively equal effectiveness in increasing response rate.
TL;DR: This method preserves many cytoplasmic features such as lipid deposits and ribosomes which are usually destroyed by permanganate fixation and apparently acts as a permeating agent allowing maximum penetration of the cell wall by the fixative without disrupting cellular fine structure.
Abstract: The primary fixative containing 2% acrolein, 2% glutaraldehyde in 50% aqueous dimethyl sulfoxide (DMSO) buffered at pH 7.4, was applied for 7 hr in the cold. After a short wash in 0.02 M s-collidine buffer, pH 7.4, containing 0.2 M sucrose and 0.001 M CaCl2, the yeast cells were postfixed in 3% OsO4 at pH 4.0 (veronal acetate buffer). This method preserves many cytoplasmic features such as lipid deposits and ribosomes which are usually destroyed by permanganate fixation. DMSO apparently acts as a permeating agent allowing maximum penetration of the cell wall by the fixative without disrupting cellular fine structure
TL;DR: It is presented that penicillinase serves an important metabolic function in producing cells, far more significant than the ability to hydrolyze certain penicillins.
Abstract: Based both on a review of the literature dealing with penicillinase induction as well as published data from this laboratory, the thesis is presented that penicillinase serves an important metabolic function in producing cells, far more significant than the ability to hydrolyze certain penicillins. An attempt is made to implicate the enzyme in the sporulation process in sporeforming cells and in cell wall metabolism in non-spore-forming organisms.
TL;DR: Two acid-soluble, high-molecular-weight peptidoglycan fractions containing muramic acid, glucosamine, diaminopimelic acid, d-aspartate, and d- and l-alanines, -lysine, -glycine, and -glutamate, distinguishable on the basis of size and different amino acid to amino sugar ratios, have been found to be responsible for the observed induction.
Abstract: In Bacillus cereus 569 a cellular inducer of beta-lactamase was isolated which has the same constituents and basic structure as the soluble peptidoglycan found in sporulation, extracts from spores, and germination extracts, and which was previously called "spore-peptide." The material has been extensively purified and characterized. Two acid-soluble, high-molecular-weight peptidoglycan fractions containing muramic acid, glucosamine, diaminopimelic acid, d-aspartate, and d- and l-alanine, -lysine, -glycine, and -glutamate, distinguishable on the basis of size and different amino acid to amino sugar ratios, have been found to be responsible for the observed induction. Both fractions are capable of inducing high levels of beta-lactamase in concentrations lower than those of benzyl penicillin required for optimal induction. Several experiments also suggest that it is the accumulation of such soluble peptidoglycan in penicillin-treated cells which leads to induction of beta-lactamase and not the penicillin itself. The "spore-peptide" inducer becomes available during sporulation, and endogenous derepression of beta-lactamase activity occurs simultaneously. Such derepression also occurs in a strain of B. cereus very sensitive to penicillin and in which both uninduced as well as "spore-peptide"-induced beta-lactamase is a small fraction of that produced by the typical penicillinase producer. These results suggest that beta-lactamase in B. cereus functions in cell wall metabolism during sporulation.
TL;DR: The viral RNA isolated from the defective particles of vesicular stomatitis virus was capable of interfering with the replication of this virus in chick embryo cells and indicates that the interfering ability of the defective particle is due to their nucleic acid component.
Abstract: The viral RNA isolated from the defective particles of vesicular stomatitis virus was capable of interfering with the replication of this virus in chick embryo cells. The data indicate that the interfering ability of the defective particles of this virus is due to their nucleic acid component.