In vivo 1-aminocyclopropane-1-carboxylate synthase activity in internodes of deepwater rice : enhancement by submergence and low oxygen levels

Inasmuch as the activity of 1-aminocyclopropane-1-carboxylate (ACC) synthase cannot be measured in homogenates of deepwater rice internodes (Oryza sativa L.), we have employed an in vivo assay to determine the activity of this enzyme. This assay is based on the accumulation of ACC in tissue kept under N₂. Submergence of whole plants or stem sections containing the uppermost, developing internode enhances the in vivo activity of ACC synthase in the stem. This stimulation of in vivo ACC-synthase activity is especially pronounced in the region of the internode containing the intercalary meristem and the elongation zone above it. Enhancement of in vivo ACC-synthase activity is evident after 2 hours of submergence and shows a peak after 4 hours. Reduced levels of atmospheric O₂, which promote ethylene synthesis and growth in internodes of deepwater rice, also enhance the in vivo activity of ACC synthase. Our results are consistent with the hypothesis that induction of ACC-synthase activity at low partial O₂ pressures is among the first biochemical events leading to internodal growth in deepwater rice.     

Mammographic changes following reduction mammaplasty

Mammographic findings after reduction mammaplasty may be similar to those seen with carcinoma. A knowledge of the expected mammographic alterations would be helpful in differentiating postoperative changes from those seen with carcinoma of the breast. Accordingly, the clinical records and mammograms of patients who underwent reduction mammaplasty at the Dartmouth-Hitchcock Medical Center between March of 1977 and July of 1985 were analyzed. Forty-two patients had at least one mammographic examination following reduction mammaplasty. Periareolar soft-tissue changes and inferior pole alterations were present in almost all examinations of patients during the first 6 months after operation, but they decreased during the next few years. Asymmetrical densities were present in approximately half the patients throughout the follow-up period but decreased in degree. Parenchymal calcifications occurred later; few x-rays showed these calcifications during the first year, but 50 percent were apparent after 2 years. Evidence of fat necrosis occurred in approximately 10 percent. Four patients had biopsies for suspicious densities. Chronic inflammation and inclusion cyst were reported. We believe that changes after reduction mammaplasty are predictable and can usually be differentiated from those associated with cancer.     

Sulfur metabolism in Beggiatoa alba

The metabolism of sulfide, sulfur, and acetate by Beggiatoa alba was investigated under oxic and anoxic conditions. B. alba oxidized acetate to carbon dioxide with the stoichiometric reduction of oxygen to water. In vivo acetate oxidation was suppressed by sulfide and by several classic respiratory inhibitors, including dibromothymoquinone, an inhibitor specific for ubiquinones. B. alba also carried out an oxygen-dependent conversion of sulfide to sulfur, a reaction that was inhibited by several electron transport inhibitors but not by dibromothymoquinone, indicating that the electrons released from sulfide oxidation were shuttled to oxygen without the involvement of ubiquinones. Intracellular sulfur stored by B. alba was not oxidized to sulfate or converted to an external soluble form under aerobic conditions. On the other hand, sulfur stored by filaments of Thiothrix nivea was oxidized to extracellular soluble oxidation products, including sulfate. Sulfur stored by filaments of B. alba, however, was reduced to sulfide under short-term anoxic conditions. This anaerobic reduction of sulfur was linked to the endogenous oxidation of stored carbon and to hydrogen oxidation.     

Differential expression of the amyloid SAA 3 gene in liver and peritoneal macrophages of mice undergoing dissimilar inflammatory episodes

The three active serum amyloid A (SAA) genes of mice, SAA 1, SAA 2, and SAA 3, are coordinately expressed in liver during acute and chronic inflammatory stimulation and experimental amyloidosis. The genes, primarily SAA 3, are also expressed extrahepatically. The apoprotein SAA 2 is the precursor of the amyloid A (AA) fibril protein that is deposited as insoluble fibrils extracellularly in spleen and other organs when amyloidosis occurs secondarily to inflammation. The exact cause of AA fibril formation is unknown. Amyloid enhancing factor is a high m.w. glycoprotein extracted from amyloidotic organs. Administration of amyloid enhancing factor alters experimental inflammation to bring about accelerated deposition of amyloid A fibrils first in spleen and later in other organs. In this study, hepatic and extrahepatic expression of the SAA genes were compared during accelerated amyloidosis relative to inflammation uncomplicated by amyloidosis. Differences in kinetics and pattern of SAA gene expression by resident peritoneal macrophages and liver were detected during four dissimilar inflammatory episodes. Macrophages expressed the SAA 3 gene solely, and to a greater extent in chronic than in acute inflammation. In accelerated amyloid induction, macrophage SAA 3 expression increased as SAA 1 and SAA 2 expression in liver decreased. However, alpha-1-acid glycoprotein expression remained elevated throughout the course of amyloid induction. The greatly increased expression of the SAA 3 gene by macrophages and decreased expression of the SAA 1 and SAA 2 genes in liver during amyloidosis, suggests that altered SAA gene expression may play a pathogenetic role in experimental amyloid deposition.     

Construction of an ordered overlapping library of bacteriophage P1 DNA in phage vector lambda D69

A library of bacteriophage P1 DNA was constructed in the phage vector lambda D69. The DNA of some 150 randomly chosen lambda-P1 hybrid phages containing P1 DNA fragments 5-10 kb in size was analyzed by restriction endonuclease digestion using enzymes EcoRI, BglII, and BamHI that cleave P1 DNA at known positions on the physical map of P1. Approximately one third of the phages contained P1 DNA inserts having two or more restriction sites for any one of these enzymes, thus allowing the location of the insert to be determined with respect to the physical map. Genetic tests allowed detection of lambda-P1 hybrid phages possessing inserts with functional P1 ban and CmR genes. A subset of 18 phages was analyzed in more detail; their P1 DNA inserts comprise an ordered collection of overlapping P1 DNA fragments that cover almost 98% of the P1 genome.     

Purine nucleotide metabolism in phytohemagglutinin-induced human T lymphocytes

The comprehensive studies of purine nucleotide metabolism were done in nonstimulated and phytohemagglutinin (PHA)-stimulated human peripheral blood T lymphocytes. Nonstimulated lymphocytes synthesize nucleotides in two alternative pathways: via biosynthesis de novo and salvage pathways. Although synthesis of triphosphonucleosides in unstimulated lymphocytes was the predominant pathway, interconversion of monophosphonucleosides was also active. Exposure of cells to PHA affects differently various pathways of nucleotide metabolism. The most marked changes observed were rapid activation of purine salvage within minutes after exposure to PHA, and significant increase of 5-phosphoribosyl-1-pyrophosphate levels. In addition, significant increases were found in de novo purine biosynthesis, nucleotide interconversions, and RNA and DNA synthesis, whereas catabolism of nucleotides remained unchanged. These results indicate that PHA activation of T lymphocytes causes a rapid synthesis of nucleotides which may be required immediately for increases in energy metabolism and later as the precursors of nucleic acid synthesis.     

Molecular diagnosis of Duchenne and Becker muscular dystrophies. Current data

Carrier diagnosis and prenatal diagnosis of Duchenne's muscular dystrophy (DMD) and Becker's muscular dystrophy (BMD) has become possible using some twenty RFLPs detected by more than a dozen Xp21 probes that are either intragenic or flanking the disease locus. Results from familial studies on 88 DMD and BM families stress important considerations concerning a priori and final risks, individuals necessary for the identification of the phase, and the different strategies that can be applied, regardless of whether the study concerns an on-going pregnancy or a carrier-status determination, and whether the patient is at high or low risk. Finally, multiple sources of difficulties in interpreting the results depend on a) the occurrence of new mutations that must be traced; b) the existence of meiotic recombination; c) the necessity, in some instances, of relying upon the sole identification of the paternal X. These considerations emphasize the characteristics and the important limitations of this type of methodology.     

Light induces a rapid and transient increase in inositol-trisphosphate in toad rod outer segments

The sub-second time course of changes in the content of [3H]inositol-1,4,5-trisphosphate was determined in rod outer segments from very rapidly frozen Bufo retinas that had been incubated with [3H]inositol. Rod outer segments were cut off frozen specimens with a cryostat microtome and the water soluble extracts were analyzed. The content of [3H]inositol-1,4,5-trisphosphate rose after approximately 250 msec of bright illumination, but returned to the unstimulated level after 1 sec, whether the stimulus remained on or not. That is, there was rapid but transient change in the content of [3H]inositol-1,4,5-trisphosphate after the onset of stimulation.     

Reconstructive surgery for immunosuppressed organ-transplant recipients

Prolonged vascularized organ allograft survival and an improved quality of life are now possible for many transplant recipients. These advances are due largely to greater understanding of the immune response, the development of potent immunosuppressive agents (cyclosporin A), and improved surgical techniques. Thus more of these patients may require surgical procedures related or unrelated to their original operation, and the plastic surgeon, among other specialists, should be aware of the special problems of the immunocompromised transplant recipient who needs to undergo reconstructive surgery. We report our experience with 15 kidney, heart, and liver transplant recipients who required reconstructive surgery for a variety of conditions. The combined team approach by reconstructive and transplant surgeons is described, as well as the perioperative drug protocol and the special problems that immunosuppressed transplant recipients present. We conclude that these patients can successfully undergo major reconstructive procedures as long as the plastic surgeon not only performs technically flawless surgery, but also familiarizes himself or herself with the special problems of the immunosuppressed host, including the ever-present risk of sepsis and delayed and impaired wound healing, the potential for acute Addisonian crisis, and the possibility of multiple complicating comorbid conditions.     

Analysis of fibrogenic processes in denervated tissues of spinal cord injury patients

To test the hypothesis that altered collagen metabolism is a contributing factor in the apparent delayed wound healing in denervated regions of spinal cord injury (SCI) patients, a tissue implant (PVA) was used to directly measure collagen deposition. Sterile PVA implants were placed subcutaneously in the inner aspect of the upper arm above the cord injury (innervated) and in the inner aspect of the upper leg below the cord injury (denervated) of 20 spinal cord injury patients and compared to eight healthy volunteers. On day 14, the implants were removed and analyzed histologically by trichrome stain and biochemically for hydroxyproline as a measure of collagen deposition. No remarkable histologic differences were observed in the sponge material removed from the upper regions compared to the lower denervated regions of the spinal cord injury patients. Sponges from both areas were infiltrated with fibroblasts containing well-developed rough endoplasmic reticulum and large quantities of trichrome-positive collagen. Likewise, upper and lower histology of controls was identical and nondistinguishable from the corresponding sections obtained from the spinal cord injury patients. Quantitation of the hydroxyproline in the arms of the spinal cord injury patients (n = 20) showed 4.3 +/- 0.7 nmol hydroxyproline per milligram of sponge compared to 4.1 +/- 0.4 nmol/mg in the denervated regions of the lower limb. The hydroxyproline content in the arms of control volunteers was 5.2 +/- 0.7 nmol/mg compared to 3.9 +/- 0.8 nmol/mg in the leg (n = 8). These observations suggest that fibrogenic processes in denervated regions are not reduced significantly compared to innervated regions.