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Biomedical subjects

A Lam

Publications and source records attributed to A Lam.

At least 91 records · Page 5Linked to original sources
PubMed1983

Construction of a broad-host-range kanamycin-resistant plasmid vector.

A new 10.2-kb plasmid, pIRL2, was constructed by using a 2140-bp DNA fragment carrying the Kmr gene and BamHI cohesive ends. These BamHI cohesive ends were used to trap the replicating DNA fragment from a partial Sau3A digest of the plasmid R300B. The plasmid contains unique EcoRI, SstI, HindIII, SmaI, SalI, and XhoI sites. These sites can be used as cloning sites without the loss of Kmr. A unique BglII site can be used as a cloning site by insertional inactivation of the Kmr structural gene, coding for neomycin phosphotransferase type II. The new plasmid carries the Sur and Smr genes of R300B. The direction of transcription from the neo promoter is clockwise, the same as that from the sul promoter. The plasmid retains the broad-host-range function of R300B, and thus it may be used for gene cloning in Rhizobium and Agrobacterium for genetic engineering of plant cells.

Cloning, Molecular↗
PubMed1983

Isolation of a new plasmid pIRL19: its use in construction of small vectors and detection of specific sequence in a foreign DNA.

A new plasmid, pIRL19, was constructed by ligating a 1875-bp HaeII fragment carrying the ampicillin-resistance (Apr) gene to a 370-bp HaeII fragment containing the replication origin of the plasmid pBR322. The plasmid essentially contains only the basic replicator and the Apr gene. This basic replicator provides a valuable initial building block for in vitro construction of other very small vectors with antibiotic-resistance determinants. To illustrate this potential, we have transferred the chloramphenicol-resistance (Cmr) gene and a part of the Apr gene from the plasmid pBR329 into pIRL19 such that the new plasmid pIRL20 acquired the Cmr gene and maintained the integrity of its Apr structural gene.

Base Sequence↗
PubMed1980

Characterization of the hormone-sensitive Ca2+ uptake activity of the hepatic endoplasmic reticulum.

The characteristics and kinetics of calcium uptake activity were studied in isolated hepatic microsomes. The sustained accumulation of calcium was ATP- and oxalate-dependent. Glucagon increased microsomal Ca2+ uptake upon either in vivo injection, or in vitro perfusion of the hormone in the liver. In contrast, the effect of insulin depended on the route of administration. Calcium accumulation by subsequently isolated hepatic microsomes increased when insulin was injected intraperitoneally whereas it decreased when the hormone was perfused directly into the liver. These effects of glucagon and insulin were dose dependent. When insulin was added to the perfusate prior to the addition of glucagon, insulin blocked the glucagon-stimulated increase in microsomal Ca2+ uptake. Cyclic AMP mimicked the effect of glucagon on microsomal Ca2+ accumulation when the cyclic nucleotide was perfused into the liver. The effects of glucagon and insulin on the kinetics of hepatic microsomal Ca2+ uptake were investigated. In microsomes isolated from perfused rat livers treated with glucagon the V of the uptake was significantly increased over the control values (12.2 vs. 8.6 nmol Ca2+ per min per mg protein, P less than 0.02). In contrast, the addition of insulin to the perfusate significantly decreased the V of Ca2+ uptake by subsequently isolated microsomes (6.8 vs. 8.3 nmol Ca2+ per min per mg protein, P less than 0.05). However, neither hormone had an effect on the apparent Km for Ca2+ (4.1 +/- 0.5 microM) of the reaction. The effect of these hormones on the activity of Ca2+-stimulated ATPase was also studied. No significant changes in either V or Km for Ca2+ of the enzymatic reaction were detected.

Adenosine Triphosphatases↗
PubMed1975

Coagulation studies in ulcerative colitis and Crohn's disease.

Thromboembolic disease is a known complication of ulcerative colitis, but is rarely reported in Crohn's disease. In this study, we have tried to determine if there are indeed coagulation abnormalities associated with these two diseases. Four groups of patients were studies: (1) patients with ulcerative colitis; (2) patients with Crohn's disease; (3) patients with other diseases; (4) healthy control subjects. In both disease groups, platelet counts, factor V, factor VIII, and fibrinogen levels were found to be elevated, while antithrombin III levels were decreased.

Adolescent↗
PubMed1975

Arterialization of the liver in combination with a portacaval shunt in the dog.

A dog preparation has been developed combining an end-to-side portacaval shunt with arterialization of the hepatic portion of the portal vein through an anastomosis between the inferior branch of the splenic artery and the stump of the portal vein. In this dog preparation, total hepatic blood flow, perfusion of the intrahepatic portal vein, and sinusoidal pressure remained within the preoperative range in the majority of the dogs. The data presented indicate that arterialization of the liver, under those conditions, resulted in no histologic damage or atrophy of the parenchyma of the liver and was effective in achieving significant prolongation of life and prevention of most of the adverse metabolic sequelae that follow a portacaval shunt in dogs. The indocyanine green extraction was restored to normal. The extraction of ammonia was impaired in all dogs with shunts; however, a significantly better ammonia extraction was seen in dogs with arterialization of the liver. It is being postulated that the dual perfusion of the liver through the hepatic artery and the portal vein is essential for the maintenance of the normal morphologic and functional states of the liver in dogs. The avoidance of hyperfusion of the sinusoidal bed with arterial blood is the most critical factor in preventing morphologic damage of the liver if arterialization of the portal vein is used.

Ammonia↗
PubMedDate not supplied

Neonatal echoencephalography.

The recent development of high-resolution real-time ultrasound scanners has coincided with the awareness of the high incidence of intracranial haemorrage in low birthweight babies, resulting in a considerable expansion in the use of echoencephalography in newborns in recent years. The uses are now further expanded and an overview of the subject is presented.

Brain Neoplasms↗