Biomedical subjects
A Ng
Publications and source records attributed to A Ng.
DNA strand breaks induced in human T-lymphocytes by the combination of deoxyadenosine and deoxycoformycin.
There is a progressive loss of human T-lymphocyte viability upon incubation with deoxycoformycin, an adenosine deaminase inhibitor, and low concentrations of deoxyadenosine (drug concentration that reduced cell count at 48 hr after initiation to 50% of value for untreated control culture, less than 1 microM). The loss of viability was evidenced by vital staining with fluorescein diacetate and by changes in forward single light scatter measured by flow cytometry. This loss of lymphocyte viability is detectable 18 to 20 hr after the addition of deoxyadenosine and is earlier than has been reported by other investigators using trypan blue as the vital stain. Alkaline elution studies show that the incubation of T-lymphocytes with the combinations of deoxycoformycin and deoxyadenosine gives rise to DNA single-strand breaks. These DNA strand breaks are dose and time dependent and are readily detected 4 hr after the addition of deoxyadenosine. These DNA lesions are not observed with deoxycoformycin or deoxyadenosine alone. Incubations of T-lymphocytes with deoxycoformycin and deoxyadenosine (1 and 5 microM) for 7 hr result in DNA strand breaks with a frequency of 145 and 280 rad equivalents, respectively. Preliminary studies indicate that the ability of lymphocytes to repair this damage is dependent upon deoxyadenosine concentration and exposure time. The relationship of these DNA lesions to loss of lymphocyte viability in the presence of deoxycoformycin and deoxyadenosine remains to be established.
Prolonged exercise in highly trained female endurance runners.
The effects of prolonged exercise in a 21 degree C dry bulb and 15 degree C wet bulb environment at 65%-70% VO2max were examined in seven highly trained females. The subjects, aged 22-35 years, underwent an initial incremental treadmill test to exhaustion, with assessment of VO2max and related cardiorespiratory variables. One week later, under similar environmental conditions, subjects ran at approximately 65% VO2max for 80 min on a motor-driven treadmill. Approximately 10 ml of venous blood was withdrawn 10 min prior and immediately prior to the onset of prolonged exercise, and at 20, 40, 60, and 80 min, and 20 min post-exercise. Venous blood was analyzed for glucose, lactate, osmolality, Na+, K+, protein, and hemoglobin (Hb). Hematocrit was measured and changes in plasma volume calculated. VO2, VE, respiratory exchange ratio, and heart rate were recorded at 17, 37, and 77 min. The percent body fat estimated from skinfold thicknesses was 19 +/- 1%. The mean VO2max was 59.3 +/- 1.0 ml . kg-1 . min-1, with a mean max VE STPD and heart rate of 78.75 +/- 3.10 1 . min-1 and 175 +/- 4 beats . min-1, respectively. No significant changes occurred in VO2, VE, % VO2max, heart rate, venous lactate, plasma glucose, or plasma protein during the prolonged exercise. A significant decrease in respiratory exchange ratio was noted. Significant changes also occurred in hematocrit, Hb, Na+, K+, and osmolality. An interesting finding was the pre-exercise expansion of the plasma volume.
Streptococcus equisimilis (group C) as a cause of ophthalmic infections.
The first two cases of human ophthalmic infections due to Streptococcus equisimilis (group C) are reported. This organism is known to produce severe infections in animals, but infection in humans is rare. The distinction between beta-hemolytic group C streptococci and group A and their ability to cause disease in susceptible patients is discussed.
Tuberculous lymphadenopathy: a review of results of surgical treatment.
Eighty consecutive cases of tuberculous lymphadenopathy confirmed by histological examination were reviewed. Fifty-five cases (69%) were followed up for more than two years. Excluding twelve cases with incomplete chemotherapy, the results of treatment by combined surgery and chemotherapy in the remaining 43 cases were analysed. Twelve cases had complete excision of all grossly involved lymph nodes; all did well. Twenty-one cases had only representative lymph nodes biopsied for diagnosis, five of them (24%) required a second operation--three for abscess formation and two for progressive enlargement of the residual lymph nodes. Seven cases of tuberculous abscesses were treated by a simple drainage procedure, and despite chemotherapy, all had persistent wound discharge for over one month which required a second operation to remove the underlying caseating lymph nodes. Results suggest that all easily accessible tuberculous lymph nodes should be removed and that persistent discharging sinuses should also be treated by surgery.
Occupation and the high risk of lung cancer in Northeast Florida.
A case-control study involving interviews with 321 male patients with lung cancer and 434 controls, or their next of kin, was undertaken to identify reasons for the high lung cancer mortality along the northeast coast of Florida. In Duval county (Jacksonville), the age-adjusted rate for lung cancer, 1970-1975, among white males was the highest of all urban counties in the United States. Increased risks on the order of 40-50% were associated with employment in the shipbuilding, construction, and lumber/wood industries, particularly among workers with reported exposures to asbestos or wood dust. Excess risks were also linked to fishing and forestry occupations, although the numbers of cases involved were small. Occupational factors did not appear to fully account for the area-wide excess of lung cancer, but no evidence was found to implicate smoking habits, migration patterns, or diagnostic and reporting practices as factors responsible for the exceptional mortality rates.
A scanning electron microscopic investigation of effects of prostacyclin on platelet retention in glass bead columns.
As whole blood passes through a column of glass beads, platelets are activated and all 3 basic platelet properties (adhesion, release reaction and aggregation) displayed, an aspect similar to platelets being involved in a hemostatic process. For this reason, we chose the platelet retention test as the tool to study the effect of synthetic prostacyclin (PGI2) on platelet function and behavior. PGI2 inhibited platelet retention with its major impact on platelet aggregation. The extent of inhibition was not proportional to the concentration of PGI2. It appears that 2 levels of platelet aggregation take place inside the column. One, triggered by a weak stimulus, is readily inhibitable by low concentrations of PGI2. The other, brought about by a strong stimulus, requires higher concentrations of PGI2 to achieve complete inhibition. Even with as much as 100 ng PGI2/ml blood, a 15% retention remained which probably represented platelet adhesion to glass beads. Scanning electron microscopic examination of glass beads showed massive platelet aggregation and adhesion in control blood samples. No platelet aggregate was observed on beads filtered with blood containing 20 ng/ml or more PGI2. Individual platelets were found on glass beads filtered with samples containing any concentrations of PGI2; these platelets exhibited extensive morphologic changes.
A controlled clinical trial testing two potentially non-cross-resistant chemotherapeutic regimens in small-cell carcinoma of the lung.
With the objectives of improving response rate, duration of response, and survival in small-cell carcinoma of the lung, 39 patients were randomized to remission-induction with either one of two potentially non-cross-resistant drug combinations: APE (consisting of adriamycin, 35 mg/m2 IV, D1 Q 3 weeks; procarbazine, 60 mg/m2 PO, D1-10 Q 3 weeks; and the epipodophyllotoxin (VP16-213), 130 mg/m2 IV, D8, 15 Q 3 weeks) or MOCC (composed of methotrexate, 15 mg/m2 IV (with [vincristine] Oncovin) or PO twice weekly D8-21 Q 3 weeks; Oncovin, 1.5 mg/m2 IV, D8, 15 Q 3 weeks; cyclophosphamide, 600 mg/m2 IV, D1 Q 3 weeks, and CCNU, 60 mg/m2 PO Q 6 weeks). A fixed crossover to the alternate regimen occurred at three months. Radiotherapy was delivered to the primary tumor (locoregional disease only) by a split course technique (1,750 rads for five days with a three-week split, followed by 3,400 rads over 17 days). The median survival including both arms was 11 months for regional and nine months for extensive disease. The chemotherapeutic activity of both regimens was comparable, with 15/17 (88 percent) of the patients responding to APE (including six complete) and 14/17 (82 percent) responding to MOCC (including five complete). The median survival for the complete responders was 11.7 months, while the partial responders survived for a median of 9.7 months. There were 2/9 (22 percent) responders to the alternate regimen at progressive disease. The overall incidence of CNS progression was 17 percent. The toxicity of the regimens was moderate, except for one instance of granulocytopenic death. This study establishes two equipotent drug combinations for the treatment of small-cell carcinoma of the lung.
New method for serological screening of typhoid carriers.
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Serological, functional, and immunochemical characterization of a monoclonal antibody (MoAb Q2/70) to human Ia-like antigens.
Serological and immunochemical studies showed that monoclonal antibody Q2/70 (MoAb Q2/70), produced by the hybridoma technique, is specific for human Ia-like antigens. This antibody recognizes an antigenic determinant which is different from those defining the serologic polymorphism of Ia-like antigens, and is expressed on subsets of human Ia-like molecules and on lymphoid cells from other species. MoAb Q2/70 inhibits unidirectional MLRs* between allogenic human lymphocytes, but not between murine and human lymphocytes. In ADCC* assays. MoAb Q2/70 mediates lysis of cultured human B lymphoid cells RPMI 4098, effected by murine splenocytes. The antibody is suitable to isolate immunologically functional B lymphocytes from human peripheral blood.
Cross-reacting xenoantibodies to human and murine beta 2-microglobulin.
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Monovalent antibodies directed to transformation-sensitive membrane components inhibit the process of viral transformation.
Monovalent antibodies (Fab) directed to two classes of transformation-sensitive cell surface components, ganglioside and galactoprotein a (Gap a), inhibit the process of oncogenic viral transformation of cells. Mouse 3T3 cells infected with murine sarcoma virus were not transformed in terms of morphology change and enhancement of sugar uptake when the infected cells were cultured in the presence of monovalent antibodies directed to GM(1) ganglioside or to Gap a. Transformation inhibitory activity of these cell surface ligands was not related to cell growth inhibition because the monovalent antibodies to globoside and divalent Con A were growth inhibitory but did not inhibit oncogenic transformation. Neither anti-GM(1) Fab nor anti-Gap a Fab inhibited virus production. The transformation inhibitory activity of antiganglioside and anti-Gap a Fab was additionally assessed by inhibiting the transformed phenotype in NRK cell lines with mutants of avian sarcoma virus that are temperature sensitive for expression of the transformation phenotype (NRK/LA25). In this cell line, the GM(3) ganglioside (not GM(1)) and Gap a were transformation-sensitive cell surface components. The expression at permissive temperature of transformed phenotypes, such as morphology change and capability of growth in 0.3% agar, was inhibited by preincubation of the cells with anti-GM(3) Fab or anti-Gap a Fab.GM(3) labeling of NRK/LA25 cells decreased at permissive temperature, whereas preincubation of cells with anti-Gap a, which induces the inhibition of transformation after a temperature shift, prevented the decline of GM(3) label on the cell surface. The data suggest a possible correlation between GM(3) and Gap a expression. Application of monovalent antibodies to these transformation-sensitive components may prevent changes of these components on cell surfaces, and thus may result in abortion of phenotypic expression of transformation, although the transforming gene (src) has been set active. These results indicate that pericellular structures influence gene expression.
The safety of local anesthesia and outpatient treatment: a controlled study of induced abortion by vacuum aspiration.
The safety of early vacuum aspiration performed as an outpatient procedure using local anesthesia was examined in a controlled study sponsored by the World Health Organization and undertaken in two centers in Yugoslavia and Singapore. The sample consisted of healthy women whose pregnancies were between 7 and 12 weeks in duration. Follow-up four weeks after abortion was nearly 100 percent in both centers. No important differences in complication rates were found between the different types of services and anesthesia, even though overall complication rates differed markedly between centers. Overnight postabortion observation was not associated with any decrease in complications.
Complications following induced abortion by vacuum aspiration: patient characteristics and procedures.
Complications following early induced abortion by vacuum aspiration were examined in a controlled study. Data were collected on healthy women 7--12 weeks pregnant at the time of abortion. No association was found between complication rates and age, marital status, or parity. However, women in their first pregnancies and those who had experienced an induced or spontaneous abortion in their previous pregnancy had a higher rate of complications following the current induced abortion.
The place of Bactrim and Vibramycin in acute salpingitis.
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Submandibular tissue obstruction of tracheostomy tube: reversal with "chin sling".
We report on a 55-year-old woman with a tracheostomy who had unexplained respiratory failure from acute nocturnal shortness of death. During the second day of admission, the patient noticed that her "second chin" folded over the tracheostomy on neck flexion, occluding her artificial way. The patient jury-rigged a strap to retain the submental tissue from occluding the opening of the tracheostomy tube. She was subsequently free from obstructive symptoms with good oxygen saturation even with neck flexion. She was consequently discharged with a presumptive diagnosis of acute upper airway obstruction. We believe that this unusual complication of the tracheostomy tube may be more common than appreciated. Accordingly, patients with a tracheostomy should be evaluated through a full range of body and neck positions. Increases in body fat and tissue relaxation should be suspected as possible causes occlusion of tracheostomy tubes. The application of a "chin sling" can reverse this unusual upper airway obstruction until definitive correction by surgical lipectomy is performed.
Peroneus brevis tendon rupture with tophaceous gout infiltration.
The authors present a patient with a history of chronic lateral ankle instability and pain. Physical and diagnostic evaluation revealed anterior ankle instability and peroneus brevis weakness. An MRI showed an attenuated anterior-talofibular ligament and a longitudinal tear of the peroneus brevis tendon. Surgical exploration exhibited tophaceous gout within the tear of the peroneus brevis as well as within the attenuated anterior-talofibular ligament. Presented is an unusual case of a longitudinal tear of the peroneus brevis tendon with tophaceous gout infiltration.