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Biomedical subjects

A Darnell

Publications and source records attributed to A Darnell.

At least 73 records · Page 4Linked to original sources
PubMed1994

Intracellular calcium concentration and activation of the Na+/H+ exchanger in essential hypertension.

To investigate the relationship between changes in intracellular calcium concentration ([Ca2+]i) and agonist-induced activation of the Na+/H+ exchanger in essential hypertension (EH), platelet [Ca2+]i and pHi were measured in 24 patients with EH (14 males) aged 48 +/- 2 years and 23 matched normotensive controls (NT) (12 males) aged 45 +/- 3 years. Measurements were done with spectrofluorimetry using the dyes Fura-2 for [Ca2+]i and BCECF for pHi. [Ca2+]i and pHi were measured in the resting condition and after stimulation in vitro with 0.1 U/ml human thrombin. The thrombin-induced rise in pHi was Na+ dependent and amiloride sensitive, indicating that it was mediated by the Na+/H+ exchanger. Unstimulated [Ca2+]i was higher in patients with EH than in NT (60 +/- 3 vs. 48 +/- 1 nmol/liter, P < 0.005), but there were no differences in resting pHi between both groups (7.16 +/- 0.01 vs. 7.16 +/- 0.008). In the presence of 1 mmol/liter external calcium (Ca2+o), thrombin-induced increment in [Ca2+]i was significantly greater in patients with EH than in NT (281 +/- 21 vs. 206 +/- 19; P < 0.05) as was the pHi increment (EH: 0.137 +/- 0.01; NT: 0.095 +/- 0.01; P < 0.05). Both agonist-induced increments in [Ca2+]i and in pHi were correlated with mean arterial pressure (MAP) only in the EH group (r = 0.58, P < 0.005 and r = 0.59, P < 0.005, respectively). The agonist-induced rise in pHi was positively correlated with the rise in [Ca2+]i both in the EH group (r = 0.65, P < 0.001) and in the NT (r = 0.55, P < 0.01).(ABSTRACT TRUNCATED AT 250 WORDS)

Blood Platelets↗
PubMed1994

Effect of antihypertensive treatment on intracellular calcium concentration and intracellular pH in essential hypertension.

The platelet intracellular calcium concentration ([Ca2+]i) and intracellular pH (pHi) were measured by spectrofluorimetry with the dyes Fura-2 and BCECF, respectively, in 19 patients with essential hypertension (10 males), aged 48 +/- 2 years, before and after 12 weeks of antihypertensive treatment and in 19 normotensive controls (11 males), aged 46 +/- 3 years. [Ca2+]i and pHi were measured in the resting state and after stimulation in vitro with 0.1 U/ml human thrombin. In patients with essential hypertension, both resting [Ca2+]i (61 +/- 4 nmol/l) and thrombin-induced maximal increase in [Ca2]i (291 +/- 26 nmol/l) were significantly (P < 0.01) greater than in the normotensive controls (resting 49 +/- 2 nmol/l and thrombin-induced 199 +/- 21 nmol/l). With respect to pHi, no difference in resting pHi between both groups was found (7.16 +/- 0.01 vs. 7.16 +/- 0.01). However, pHi increment at 300 seconds in response to thrombin was higher in the patients with essential hypertension than in the controls (0.131 +/- 0.02 vs. 0.083 +/- 0.01 pH units, P < 0.05). The increment in pHi was blunted by the amiloride derivative EIPA, indicating that it was mediated by the Na+/H+ exchanger. After antihypertensive therapy in the essential hypertensive patients, basal [Ca2+]i was significantly reduced (52 +/- 2 nmol/l, P < 0.01) and was not statistically different to the value found in the normotensive controls. Resting pHi suffered no significant modification after treatment (7.17 +/- 0.01, P = NS).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1993

[Systemic lupus erythematosus: a clinical and immunological study of 300 patients].

BACKGROUND: The aims of the present study were to analyze the clinical and immunologic characteristics of a wide group of patients with systemic lupus erythematosus (SLE) and define homogeneous subgroups with their own characteristics. METHODS: A prospective study of 300 patients diagnosed of SLE were studied. These patients were subdivided according to sex, age at the onset of the disease and immunologic profile. The statistical study was carried out by the chi (2), Fisher, Student's t and Mann-Whitney U tests. RESULTS: The series was made up of 266 (89%) females and 34 (11%) males. The mean age at onset of the disease was 31.8 +/- 14.6 years. In 48 (16%) patients the first manifestations appeared after the age of 50. Males were shown to present a lower prevalence of arthritis (59% vs 82% in woman, p < 0.005) and malar rash (29% vs 50%, p < 0.05), but had more cutaneous discoid lesions (18% vs 3% p < 0.001). In patients in whom the disease appeared after the age of 50 a lower prevalence of arthritis was presented (67% vs 82% in patients of less than 50 years of age, p < 0.005), malar rash (23% vs 53%, p < 0.001) and nephropathy (21% vs 41%, p < 0.05), but had greater myositis (17% vs 6%, p < 0.01). The absence of antinuclear antibodies (ANA) and the presence of anti-ds DNA and anti-ENA antibodies were associated with differences in the prevalence of different clinical manifestations. CONCLUSIONS: Sex, age and immunologic pattern in systemic lupus erythematosus permit the definition of homogeneous subgroups with their own characteristics: a) males present a lower prevalence of arthritis and malar rash, but a greater prevalence of cutaneous discoid lesions; b) patients over the age of 50 develop arthritis, malar rash and nephropathy with a lower prevalence but have a greater prevalence of myositis; c) patients without antinuclear antibodies and those with anti-ds DNA and anti-ENA antibodies present differences in the prevalences of different clinical manifestations.

Adolescent↗
PubMed1990

[Incidence and characteristics of glomerular diseases after kidney transplant].

The incidence of glomerular diseases was retrospectively reviewed in our population of renal transplants performed during the period 1972-1988. Overall, 42 instances of post-transplant glomerular disease were observed in 39 patients. The most common type of glomerular disease was transplant glomerulopathy in 13 cases, followed by membranous glomerulonephritis in 8. Regarding etiology, relapse of the original nephropathy was considered to be present in 15 patients and de novo glomerular disease in the remaining 27. In our series, the incidence of clinical relapses was 12%, ranging between 75% in hemolytic-uremic syndrome and 8% in mesangiocapillary glomerulonephritis. 50% of those patients who developed glomerular disease after transplant had a loss of their grafts during the follow up period. The survival of the graft, from 6.5 years after transplant onwards, was significantly lower than that seen in the group of transplanted patients without glomerular disease.

Adolescent↗
PubMed1990

Silent renal microangiography after mitomycin C therapy.

Mitomycin C (MMC) is an alkylating agent which has been associated with microangiopathic hemolytic anemia and acute renal failure, with an overall incidence between 2 and 10%. This complication can develop several months after the initiation of chemotherapy. Isolated renal impairment without overt microangiopathic hemolytic anemia, although reported, is less frequently documented. We describe a 63-year-old man who developed progressive renal failure without any evidence of hemolysis or thrombopenia 10 months after beginning chemotherapy with MMC and Ftorafur. A renal biopsy displayed features of microangiopathy. The patient required the institution of chronic hemodialysis. In conclusion, it is important to be aware of this indolent but severe renal complication in patients treated with MMC. Urinary parameters and renal function should be monitored over a long period for an early diagnosis.

Adenocarcinoma↗
PubMed1989

Cellular immunity analysis using monoclonal antibodies in human glomerulonephritis.

Monoclonal antibodies against class II antigens of the human major histocompatibility complex (MHC) (Edu 1), von Willebrand factor-related antigen marker of endothelial cell, T cells (Cris 1), helper/inducer T cells (T4) and cytotoxic/suppressor T cells (T8) by indirect immunofluorescence, and stain for nonspecific esterase characterizing monocytes-macrophages (Mo-Ma) were applied in 64 renal biopsies--54 glomerulonephritis (GN), 10 non-GN- and in 14 normal kidneys. Class II antigens were expressed on the endothelium of renal microvasculature in all specimens. Intraglomerular T cells and Mo-Ma were only present in GN. Mo-Ma appeared associated with endo- and extracapillary proliferation (Xc2 = 4.68; p less than 0.05), C3 (X2 = 4.21; p less than 0.05), and fibrinogen (X2 = 3.84; p less than 0.05) deposition; and those were most numerous in biopsies with intraglomerular T cells. Interstitial MHC-class II+ cells (Xc2 = 5.5; p less than 0.02), T cells (F = 3.37; p less than 0.005) and Mo-Ma (F = 2.45; p less than 0.05) were significantly higher in GN with endo- or extracapillary proliferation than in the remaining. In GN, correlations were seen between T cells and MHC-class II+ cells (r = 0.63; p less than 0.001), and Mo-Ma (r = 0.38; p less than 0.02), infiltrating the interstitium. Our results suggest that both humoral and cellular immunity contribute to macrophage glomerular infiltration in the human GN. Mononuclear cells, and no intrinsic renal cells, would be implicated in the cellular immune interactions in situ.

Adolescent↗
PubMed1988

Renal amyloidosis with nephrotic syndrome in a Spanish subcutaneous heroin abuser.

A 25-year-old drug addict who practices subcutaneous injection of heroin and crushed narcotic tablets, a practice known as 'skin popping', developed nephrotic syndrome secondary to renal amyloidosis. The patient had chronic inflammation of the skin in the form of abscesses and ulcerations. She had practiced subcutaneous drug administration for only 2 years. Amyloidosis had the staining characteristics and tissue distribution of the secondary type, and was directly related to chronic skin suppuration. To our knowledge, this represents the first reported case of renal amyloidosis in a subcutaneous drug abuser residing in Europe.

Adult↗
PubMed1987

Silent renal disease in systemic lupus erythematosus.

Several recent studies have focused on the discrepancy between lupus nephropathy and clinical renal involvement and, consequently, question the relevance of renal biopsy in these patients. We analyze the clinical characteristics, histological renal findings and subsequent course of patients with silent renal disease. Renal biopsy was performed in 15 patients with systemic lupus erythematosus (SLE) who had no clinical signs of renal involvement (no urinary sediment abnormalities, absence of proteinuria and serum creatinine less than 1.3 mg/dl). All biopsies were classified according to a modified classification proposed by the WHO. Six cases (40%) showed no histological or immunofluorescence changes (type I), 7 (47%) had mesangial nephropathy (3 type IIa and 4 type IIb) and 2 (13%) had focal proliferative glomerulonephritis (type III). None of the patients had previous evidence of neurological abnormalities. Patients with type I only had arthritis, skin lesions and Raynaud's phenomenon. By contrast, 7 patients with histological renal involvement had serositis or hemolytic anemia. All cases with silent nephropathy were treated with steroids and showed a benign clinical course with stable renal function and absence of urinary abnormalities during follow-up. We concluded that in the absence of clinical renal abnormalities, renal involvement is not uncommon in SLE. We believe that a renal biopsy should be performed mainly in those SLE patients presenting with clinical manifestations other than arthritis or cutaneous lesions since this policy may allow detection of significant silent renal injury.

Adolescent↗
PubMed1987

Malignant or accelerated hypertension in IgA nephropathy.

A retrospective analysis of 66 adult patients diagnosed as having IgA nephropathy by renal biopsy revealed that 24 (36%) were hypertensive when first seen. Of these hypertensive patients, 10 (15%) had malignant or accelerated hypertension. All patients but one were male and had no knowledge of their renal disease and sought medical advice for symptoms due to hypertension. Five patients had no history of gross hematuria. Histological vascular findings showed, in three proliferative endarteritis and fibrinoid necrosis, in five arteriolosclerosis and in two vascular hypertrophy. In spite of good blood pressure control, six patients reached terminal uremia within a maximum of 14 months. In summary, the incidence of malignant hypertension in adults with IgA nephropathy is higher than previously reported, and its true incidence can only be known if more histopathologic studies of patients with malignant hypertension are performed. Patients with this association reach end stage renal failure in a short period of time.

Adult↗
PubMed1986

Glomerular disease in cirrhosis of the liver: low frequency of IgA deposits.

Twelve HBsAg-negative patients with histologically documented cirrhosis of the liver of either alcoholic (8 of 12) or cryptogenic (4 of 12) origin underwent renal biopsy to investigate proteinuria, hematuria and/or renal failure. Immunofluorescence was positive for IgA in 2 patients with mesangiocapillary glomerulonephritis (MCGN) and could not be performed in 2 additional patients with the same diagnosis. However, in the remaining 8 patients, immunofluorescence was negative for IgA and frequently positive for C3, IgG, IgM and/or fibrinogen. These 8 patients without IgA were classified as follows: MCGN with subendothelial electron-dense deposits (2 cases), IgM-IgG cryoglobulinemia with diffuse endocapillary glomerulonephritis (1 case), membranous nephropathy (1 case), diffuse endocapillary proliferative glomerulonephritis (1 case), vasculitis with focal segmental necrotizing glomerulitis and crescentic glomerulonephritis (2 cases). These results show that cirrhosis of the liver can be associated with a wide variety of glomerular disorders. Contrary to previous belief, IgA is absent in two thirds of patients with cirrhosis and glomerulopathy. Therefore, the pathogenetic importance of IgA in the development of glomerular disease in such patients is doubtful.

Adult↗