Biomedical subjects
Publications and source records attributed to J Singer.
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The restriction enzymes Hpa II and Msp I both recognize the sequence 5'-CCGG (C, cytosine; G, guanine). However, Hpa II cuts mouse liver DNA to fragments four times larger than does Msp I. The size of DNA cut by Msp I is close to that predicted from base composition and nearest neighbor analysis. The most probable explanation of these results is that in mouse the site 5'-CCGG is highly methylated.
Simultaneous recordings of the fetal electrocardiogram and ultrasound Doppler-cardiogram were used for the determination of the pre-ejection period (PEP) of the fetal cardiac cycles. All 50 fetuses selected for the present study experienced uneventful perinatal lives despite maternal antepartum complications which required hospitalization. A significant positive correlation between the PEP and gestational age of the fetuses was again demonstrated. The PEP of the fetus measured within one week prior to delivery was also found to be significantly correlated with the newborn body weights at birth. Statistical analysis demonstrates that fetal body weight was more closely related to the physiologic lengthening of the PEP.
1. Consumer rights apply to the practice of orthodontics as well as other areas of health care. 2. To avoid consumer complaints, the orthodontist must be prepared to deal with personality problems as well as treatment complications in his practice. 3. Only by careful questioning of the patient before treatment will the orthodontist be able to detect possible future problems. 4. An explanation of informed consent by the orthodontist and an acknowledgement of it in writing, signed by the parent or responsible party, is now regarded as essential to avoid misunderstandings and complaints. 5. An informed patient leads to a better relationship with the orthodontist as well as a healthier atmosphere in which to practice.
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Trauma to the lower extremities is the principal cause of gait disturbance in early childhood. Three cases are presented to emphasize the relative frequency of children hospitalized for diagnostic evaluation of altered gait who have occult fractures. The cases may refresh the primary physician of the variables that serve as obstacles to accurate diagnosis.
Suppurative meningitis should be recognized as being a complication of varicella. The clinician must assiduously exclude suppurative meningitis that at times may be clinically indistinguishable from the typical postinfectious encephalomyelitis of varicella. Misdiagnosis of the cause of CNS alterations during the course of varicella is possible.
The glucose-6-phosphate dehydrogenase (G.-6-P.D.) types of isolated blood-cell populations and normal skin were determined in two patients with chronic lymphocytic leukaemia (C.L.L.) who were heterozygous at the G.-6-P.D. locus. Normal tissues from each patient manifested both A and B G.-6-P.D. types, but the C.L.L. B-lymphocyte preparation from one patient showed only a single enzyme type, and from the other patient it showed 95% activity of one G.-6-P.D. type. These observations confirm the supposition based on immunoglobulin-marker data that at the time of study C.L.L. has a clonal origin. In contrast to the B lymphocytes, granulocytes, erythrocytes, platelets, and T lymphocytes displayed both enzyme types in proportions similar to those found in skin. These findings indicate that C.L.L. involves committed B-lymphocyte progenitors. Thus, the disease stands in contrast to chronic myelocytic leukaemia and other myeloproliferative syndromes, all of which involve multipotent haemopoietic stem cells.
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The ability of tumor markers to improve cancer therapy is not established. We studied a man with a human chorionic gonadotropin (HCG)-secreting large cell carcinoma of the lung and gynecomastia. Preoperatively, levels of HCG (109 ng/ml), its alpha and beta subunits (3.2 and 21 ng/ml, respectively) and plasma estradiol were elevated. Despite apparently complete tumor resection and total resolution of gynecomastia, HCG titers remained elevated (3.3 ng/ml), heralding tumor recurrence three weeks later. Because the pathophysiologic consequences of the ectopic secretion of HCG on pituitary function are not established, we administered 100 microgram of gonadotropin-releasing hormone (LHRH) and observed a markedly delayed increase in pituitary gonadotropins. Early chemotherapy, guided by persistence of HCG, reduced HCG to undetectable levels, restored to normal the response to LHRH and resulted in a distinctly unusual 30-month complete remission. Use of HCG as a tumor marker levels is more sensitive than the symptom of gynecomastia and may permit detection of small, potentially curable tumor foci.
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The aim of these experiments was to test whether incorporation of bromodeoxyuridine into DNA affects DNA methylation. Rat hepatoma (HTC) cells in culture were labeled for two generations with [14C]bromodeoxyuridine and [3H]thymidine to yield DNA which was 2.1, 20.6, 52.6, and 95.0% bromodeoxyuridine-substituted in the newly made strands. The DNA then was fractionated into highly repetitive, moderately repetitive, and single copy sequences. As determined by a comparison of 14C and 3H counts per min, the percentage of substitution with bromodeoxyuridine was found to be the same in each repetition class. The 5-methylcytosine content of each fraction was determined using high pressure liquid chromatography. It was found that bromodeoxyuridine, even at a level of substitution into newly mad DNA of 95%, has no effect on the 5-methylcytosine content of DNA. At all levels of bromodeoxyuridine substitution, highly repetitive DNA has slightly more 5-methylcytosine (3.0% of total cytosine) than does single copy DNA or moderately repetitive DNA (2.3%). The 5-methylcytosine content of whole HTC DNA is the same as that of rat liver DNA (2.4%).
The management of cardiac arrests in infants and children is based upon principles common to management of arrests of all age groups. Specific pediatric disease states predispose the patient to arrest. Special adaptions and pharmacologic management are required for pediatric cardiopulmonary resuscitation.
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One hundred patients, 54 with acute myelogenous leukemia (AML) and 46 with acute lymphoblastic leukemia (ALL), considered to be in the end stages of their disease, after combination chemotherapy were treated by marrow transplantation. All patients were given a marrow graft from an HLA-identical sibling after receiving 1000-rad total body irradiation (TBI). One group of 43 patients was given cyclophosphamide (CY), 60 mg/kg on each of 2 days, 5 and 4 days before TBI. In a second group of 31 patients, additional chemotherapy was given before CY and TBI. In a third group of 19 patients, BCNU was given before CY and TBI. A fourth group of 7 patients received other chemotherapy regimens before TBI. Six patients died 3-17 days after marrow infusion without evidence of engraftment. Ninety-four patients were engrafted and only one patient rejected the graft. Thirteen patients are alive with a marrow graft, on no maintenance antileukemic therapy, and without recurrent leukemia 1-4 1/2 yr after transplantation. Three have chronic graft-versus-host disease (GVHD). Four patients are alive 1 1/2 - 3 1/2 yr after grafting but have had a relapse of their leukemia. Of 93 evaluable patients, 19 did not develop GVHD and 24 developed very mild GVHD. Fifty patients developed moderate to severe GVHD, and 40 of these were treated with antithymocyte globulin. Interstitial pneumonia occurred in 54 patients and was the primary cause of death in 34. Interstitial pneumonia often occurred in association with GVHD and the most common etiologic agent was cytomegalovirus. A total of 31 patients have had a relapse of leukemia. There was no definite correlation between relapse of leukemia and the presence or absence of GVHD. The relapse rate appeared to be relatively constant over the first 2 yr and was extremely low after that time. Neither survival nor leukemic relapse appeared to be influenced by the type of leukemia nor by the preparative chemotherapy regimen given before TBI. Patients in fair clinical condition at the time of transplantation showed significantly longer survival times than patients in poor condition (p = 0.001). This observation, coupled with the observation that some patients may be cured of their disease, indicates that marrow transplantation should now be undertaken earlier in the management of patients with acute leukemia who have an HLA-matched sibling marrow donor.