Microbial Community and Biochemical Dynamics of Biological Soil Crusts across a Gradient of Surface Coverage in the Central Mojave Desert

In this study, we expand upon the biogeography of biological soil crusts (BSCs) and provide molecular insights into the microbial community and biochemical dynamics along the vertical BSC column structure, and across a transect of increasing BSC surface coverage in the central Mojave Desert, CA, United States. Next generation sequencing reveals a bacterial community profile that is distinct among BSCs in the southwestern United States. Distribution of major phyla in the BSC topsoils included Cyanobacteria (33 ± 8%), Proteobacteria (26 ± 6%), and Chloroflexi (12 ± 4%), with Phormidium being the numerically dominant genus. Furthermore, BSC subsurfaces contained Proteobacteria (23 ± 5%), Actinobacteria (20 ± 5%), and Chloroflexi (18 ± 3%), with an unidentified genus from Chloroflexi (AKIW781, order) being numerically dominant. Across the transect, changes in distribution at the phylum (p < 0.0439) and genus (p < 0.006) levels, including multiple biochemical and geochemical trends (p < 0.05), positively correlated with increasing BSC surface coverage. This included increases in (a) Chloroflexi abundance, (b) abundance and diversity of Cyanobacteria, (b) OTU-level diversity in the topsoil, (c) OTU-level differentiation between the topsoil and subsurface, (d) intracellular ATP abundances and catalase activities, and (e) enrichments in clay, silt, and varying elements, including S, Mn, Co, As, and Pb, in the BSC topsoils. In sum, these studies suggest that BSCs from regions of differing surface coverage represent early successional stages, which exhibit increasing bacterial diversity, metabolic activities, and capacity to restructure the soil. Further, these trends suggest that BSC successional maturation and colonization across the transect are inhibited by metals/metalloids such as B, Ca, Ti, Mn, Co, Ni, Mo, and Pb.

Prednisone withdrawal late after adult liver transplantation reduces diabetes, hypertension, and hypercholesterolemia without causing graft loss

We prospectively withdrew prednisone in 28 adult patients who had stable graft function more than 2 years after orthotopic liver transplantation (OLTx) and had been on 5 mg/d prednisone for at least 6 months. Prednisone was decreased from 5 mg/d to 2.5 mg/d for 1 month then stopped completely. Cyclosporine monotherapy was maintained at a level of approximately 200 ng/mL (TDX). Nineteen patients had prednisone withdrawn without complications. Four (14.2%) had modest elevations in liver function tests (two biopsy proven mild rejections and two were not biopsied). These four were treated with methylprednisolone boluses and then withdrawal of steroids again. Prednisone was restarted in five patients because of generalized fatigue and body aches (n = 4) and colitis (n = 1). Steroids later were successfully withdrawn in two of these patients. After prednisone withdrawal, three of five insulin-dependent diabetic patients were able to discontinue insulin therapy and their glycosylated hemoglobin levels improved. Four of fourteen hypertensive patients were able to discontinue antihypertensive medicines. Mean serum cholesterol decreased from 222.6 +/- 43.3 to 188.3 +/- 33.3 mg/dL (P < .001). The number of patients with serum cholesterol levels > 220 mg/dL decreased from 13 to 4. A control group of 24 patients maintained on 5 mg/d prednisone at least 2 years after liver transplantation also was studied. In this group during the study period, no diabetic became normoglycemic, no patient decreased their antihypertensive medicine, and the mean serum cholesterol levels did not change significantly. We conclude that prednisone withdrawal using cyclosporine monotherapy late after liver transplantation does not lead to graft loss and decreases the prevalence of diabetes, hypertension, and hypercholesterolemia. Symptoms occurring during withdrawal may be minimized by earlier or slower tapering.

Metabolic complications after liver transplantation. Diabetes, hypercholesterolemia, hypertension, and obesity

We retrospectively studied the incidence of diabetes, hypercholesterolemia, hypertension, and obesity in 123 consecutive adult liver transplant recipients (61 men and 62 women) who were alive at least 1 year after transplantation. We also studied the change in these metabolic complications in 61 patients who subsequently were able to be tapered to 5 mg prednisone per day. One year after transplantation--a point at which almost all patients were on maintenance immunosuppression and had stable graft function--the incidence of diabetes was 13% and hypertension was 69.1%. The overall incidence of hypercholesterolemia (serum cholesterol > 240 ng/ml) was 31% and was more frequent in women than in men (38.7% vs. 23.0%, P < 0.06). The incidence of obesity at 1 year was 41.9% in women and 39.3% in men. With tapering of prednisone from 10 mg to 5 mg per day in 61 patients, the mean serum cholesterol decreased from 224.6 +/- 65.2 mg/dl to 203.3 +/- 65.5 mg/dl, P < 0.005. With steroid tapering, 8 patients were able to discontinue antihypertensive medications and 4 were able to discontinue insulin treatment for diabetes. Five patients became obese during the steroid-tapering period. No patient developed irreversible rejection with steroid tapering and no immunologic graft losses occurred more than a year after transplantation. Nine patients who lived a year subsequently died. Of these, 7 patients were diabetic and 2 died of cardiac disease. We conclude that metabolic complications such as diabetes, hypertension, and hypercholesterolemia are common later after liver transplantation and that these may contribute to patient morbidity and mortality. In addition, we conclude steroid tapering to 5 mg/day does not lead to graft loss and may decrease the incidence and severity of late metabolic complications.

Progress in and deterrents to orthotopic liver transplantation, with special reference to survival, resistance to hyperacute rejection, and biliary duct reconstruction

Before I begin, I want to add my own personal reminiscence. I knew Dave Hume for almost 14 years, slightly for the first 4 and well for the last 10. I first talked to him at an elevator entrance at the Greenbrier Hotel in West Virginia, in April, 1959, and for the last time in April, 1973, in the lower lobby of the Century Plaza Hotel in Los Angeles. In May, 1973, I was in the railroad station in Albuquerque, New Mexico, when I learned from my grief-stricken youngest son that Dave was dead. It is strange how the exact details of these and some other memories in between, of the time I spent with Dave Hume, stand out with the same clarity as what I was doing when I learned of the bombing of Pearl Harbor, the assassination of John Kennedy, but very few other things. The most eloquent tribute to Dave Hume I have heard was the briefest, coming from a non-medical friend who told me sadly, “He really was a dynamite guy!”

The complement system in renal homograft recipents

The whole serum complement and its components were studied in 24 recipients of 27 renal homografts. In 12 of 13 instances in which homograft rejection was diagnosed, it was accompanied by significant declines in CH50, IA50, C4, and C3 levels, and to a lesser degree in C1 and C2 levels. Fourteen patients had normal graft function during the postoperative course of study, and in 13 of the 14 the complement levels were within the normal range throughout. In two recipients with systemic lupus erythematosus, very low initial complement levels increased to normal levels following removal of the native kidneys, splenectomy, and the provision of a well-functioning homograft. Anticomplement activity and elevated titers of C1 and C3 inactivators were observed in some patients, but these did not correlate with the changes in CH50. The findings confirm that the complement system participates in renal homograft rejection.

Serum complement after orthotopic transplantation of the human liver

In five patients with terminal liver failure, replacement of the diseased liver with a well functioning homograft restored markedly depressed total complement and C4 and C3 to normal levels. Concomitantly, C5 protein also increased. Postoperatively, two patients developed a marked drop in C4 and C3 probably in relation to homograft rejection. In contrast, serum hepatitis and biliary obstruction were not accompanied by significant changes. It is concluded that the liver is an important source of synthesis of C4, C3 and C5 and that complement assays might aid in otherwise equivocal diagnosis of hepatic homograft rejection.

Detection of Australia antigen by biological assay in 'Au negative' kidney homograft recipients with hepatic dysfunction

Rabbits were immunized with the sera from patients with known Au antigenaemia; from kidney homograft recipients who were Au negative with direct conventional tests but who had hepatic dysfunction; and from normal volunteers. Heterologous anti-Au antibodies were raised by the first of these kinds of sera but not by the third. Sera from seven of the eleven immunosuppressed kidney recipients of the second group did not raise anti-Au antibodies in the rabbit, but sera from the other four did. The results indicate that the Au antigen may be present in trace quantities in significant numbers of immunosuppressed patients previously thought to be Au negative. However, they do not unequivocally establish an aetiologic association between Au antigenaemia and `post-transplantation liver disease', probably because of the obscuring and important factor of hepatotoxicity of the immunosuppressive agents.

Immunosuppression, liver injury, and hepatitis in renal, hepatic, and cardiac homograft recipients: with particular reference to the Australia antigen

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Cyclophosphamide and human organ transplantation

Cyclophosphamide, a drug that has not previously had an important role in whole-organ transplantation, was given as a primary immunosuppressant to one liver and eleven kidney recipients, in combination with prednisone and horse antilymphocyte globulin. One of the patients died despite good renal-graft function. Two kidneys from a common cadaveric donor failed. The other nine patients have excellent function of their homografts after 2–3 months. Cyclophosphamide was substituted for azathioprine in one hepatic and five renal recipients who were suspected of having liver toxicity from azathioprine 3 months to almost 8 years post-transplantation. Graft function was maintained after this change, and the evidence of liver injury subsided.

Renal homotransplantation in pediatric patients

Fifty-seven patients were treated with renal homotransplantation from 1½ to 7⅔ years ago; 23 patients were 12 years or younger and the other 34 patients were 13 to 18. Family members (usually parents) were the primary donors in 45 cases. Unrelated volunteers or cadavers donated the other 12 homografts. Immunosuppression was with azathioprine and prednisone, and in some cases also with ALG. Forty-two of the 57 recipients survived for at least 1 year. Additional deaths occurred at 17½ and 19 months leaving 40 recipients (70.2%) alive. Six survivors had successful retransplantation following late failure of their original homografts. Control of rejection was not particularly different than in adult cases. “Homograft glomerulonephritis” was found in chronically tolerated transplants, but no more frequently than in older patients. Many postoperative problems in the pediatric age group were the consequence of retardation of growth caused either by pre-existing uremia or by the need for high dose postoperative steroid therapy, orthopedic accidents such as femoral and vertebral fractures, and psychiatric complications which led to two suicides. In spite of these difficulties, the meaningful rehabilitation that was obtained in the chronic survivors makes us regard pediatric patients as favorable candidates for therapy with renal transplantation.