Altered sulfhydryl reactivity of hemoglobins and red blood cell membranes in congenital Heinz body hemolytic anemia.

The mechanisms of hemoglobin precipitation into Heinz bodies and hemolytic anemia that characterize congenital Heinz body hemolytic anemia (CHBHA) were studied in patients with the unstable hemoglobins, Köln (beta-98 valine --> methionine) and Hammersmith (beta-42 phenylalanine --> serine). The cysteines in the 93rd position of the beta-chains of CHBHA hemoglobins bound glutathione excessively in mixed disulfide linkage. The resulting diminished "free" GSH within the cell accelerated hexose monophosphate shunt metabolism. The unique precipitability of CHBHA hemoglobins when heated at 50 degrees C could be induced in normal hemoglobin A by artificially blockading its sulfhydryl groups with paramercuribenzoate (PMB). Reflecting the previously reported excessive flux of hemes from hemoglobin Köln, the expected heme/globin ratio in this hemoglobin was reduced by 30%. The further increment in heme loss that occurs with heat (50 degrees C) underlies the unique heat precipitability of CHBHA hemoglobins; it was retarded if detachment of heme was inhibited by cyanide or carbon monoxide.Heinz bodies were attached to red cell membrane thiol groups presumably through mixed disulfide bonds, being released by mercaptoethanol. Binding of hemoglobin Köln-(59)Fe to red cell ghosts, which was markedly enhanced when Heinz bodies were generated at 50 degrees C, was inhibited if membrane thiols were preblockaded by PMB. The depletion of membrane thiols by their reaction with Heinz bodies rendered CHBHA red cells hypersusceptible to membrane sulfhydryl inhibitors, as manifested by inordinate cation leakage, osmotic fragility, and autohemolysis. We conclude that both cellular and membrane thiols bind beta-93 sulfhydryls of CHBHA hemoglobins as mixed disulfides. Concomitantly, heme avidity to beta-92 lessens, suggesting that degradation of the resulting excessively freed heme may produce the pigmented dipyrroluria of this syndrome. Heinz bodies, reflecting the heightend precipitability of heme-deficient globin, attach to, thereby depleting, membrane sulfhydryl groups. This, as shown previously, could underlie the hemolytic anemia of this syndrome by causing membrane hyperpermeability, premature splenic entrapment, and ultimately osmotic destruction of red blood cells.

Selective parathyroid venous sampling in patients with complicated hyperparathyroidism.

OBJECTIVE: The role of preoperative localisation of abnormal parathyroid glands remains controversial but is particularly relevant to the management of patients with recurrent or persistent hyperparathyroidism and familial syndromes. We report our experience of the use of selective parathyroid venous sampling (PVS) in the localisation of parathyroid disease in such patients. DESIGN: We report a retrospective 10-year experience (n = 27) of the use of PVS in complicated primary hyperparathyroidism and contrast the use of PVS with neck ultrasound, magnetic resonance imaging (MRI), computed tomography (CT) and sestamibi imaging modalities. RESULTS: In 14 out of 25 patients who underwent surgery PVS results were completely concordant with surgical and histological findings and 88% of patients achieved post-operative cure. Out of 13 patients referred after previous failed surgery, 12 underwent further surgery which was curative in 9. In total PVS yielded useful positive (n = 13) and/or negative information (n = 6) in 19 out of 25 patients undergoing surgery. Using histology as the gold standard, 59% of PVS studies were entirely consistent with histology, as compared with 39% of ultrasound scans, 36% of sestamibi scans and 17% of MRI/CT scans. CONCLUSIONS: PVS is a valuable adjunct to MRI/CT and sestamibi scanning in selected patients with complicated hyperparathyroidism when performed in an experienced unit.

Autoimmune hemolytic anemia.

Warm-type autoantibodies of autoimmune hemolytic anemia (AIHA) are usually IgG but may be IgM or IgA. They are usual Rh specific. Cold-type antibodies are IgM or IgG (Donath-Landsteiner [DL] antibody). IgM antibodies are usually anit-l (occasionally anti-i) and DL antibodies anti-P. The warm IgG antibodies do not fix complement (C); they cause red blood cell (RBC) destruction predominantly in the spleen as the result of interaction between fixing; they cause RBC destruction either by intravascular lysis (complement sequence completed) or by interaction between C3-coated RBCs and phagocytes in liver and spleen. Gentic factors, immunoglobulin deficiency, somatic mutation, viral infections and drugs, and failure of T-lymphocyte function, all probably play a part in breaking immunological tolerance and the development of AIHA.

Relative contributions of inferior petrosal sinus sampling and pituitary imaging in the investigation of children and adolescents with ACTH-dependent Cushing's syndrome.

Selective transsphenoidal microadenomectomy is the first line treatment of childhood Cushing's disease, with accurate preoperative localization of the corticotroph adenoma an important step in its investigation. Inferior petrosal sinus sampling (IPSS) for ACTH after CRH stimulation is a recognized investigation in adults, but there are few data in the pediatric age range. We report the relative contributions of IPSS and pituitary imaging in 11 patients, aged 10.7-18.8 yr, presenting with Cushing's disease. All underwent transsphenoidal surgery (TSS). IPSS was performed without complication. Sampling was from the inferior petrosal sinuses in 7 patients and the high jugular veins in 4 (patients 2, 4, 5, and 10). The central to peripheral ACTH (IPS/P) ratios were more than 2 (2.5-157.2) in 10 of 11 patients, confirming central ACTH secretion. In 3 patients with high jugular sampling, IPS/P ratio ranged from 2.5-21.1. In the fourth patient with high jugular sampling (IPS/P ratio, 0.95), a central adenoma was identified surgically, and the patient was cured after TSS. The interpetrosal sinus ACTH gradient (IPSG) was more than 1.4 (2.1-20.8) in 10 patients, indicating lateralization of ACTH secretion to the right side in 6 patients and to the left in 4. IPSG ratios were 2.1-8.5 in 3 patients with high jugular sampling. Pituitary imaging (computed tomography and or magnetic resonance imaging) was reported to identify an adenoma in 5 of 11 patients. At operation a tumor was visualized by the same surgeon in all 11 cases. In 9 patients with lateralization on IPSS, the correct side of the tumor was confirmed at surgery. In a 10th patient with a negative IPSG, a central tumor was present. Thus, IPSS gave a 91% prediction of correct tumor localization. In only 1 of 5 patients with an adenoma reported on pituitary imaging was this localization confirmed at surgery, a prediction rate of only 9%. After TSS, 8 patients were cured, 1 was in remission, and 2 required pituitary irradiation. In 73% of patients undergoing IPSS, localization of the adenoma was followed by surgical cure or remission. Pituitary scanning was therefore relatively unhelpful in localizing the adenoma. In experienced hands, however, IPSS was feasible in this age group, safe, and strongly predictive of the site of the adenoma, leading to a high rate of successful surgical outcome.

A critical analysis of the value of simultaneous inferior petrosal sinus sampling in Cushing's disease and the occult ectopic adrenocorticotropin syndrome.

The clinical, biochemical, and radiological features of pituitary ACTH-dependent Cushing's syndrome (CS) [Cushing's disease (CD)] are often indistinguishable from those of occult ectopic ACTH-dependent CS (oEAS). We have evaluated, retrospectively, the results of simultaneous bilateral inferior petrosal sinus (IPS) ACTH sampling before and after CRH stimulation in 128 patients with ACTH-dependent CS: 107 patients with CD, 6 with oEAS, 1 with an adrenal adenoma, 1 with a pituitary gangliocytoma, and 1 with Nelson's syndrome; while, in the remaining 12, the source remains unclear. One hundred seven patients received human-sequence CRH (hCRH), and 11 received ovine CRH; another 6 patients underwent stimulation with desmopressin and hCRH, and 4 with desmopressin alone. A successful bilateral IPS catheterization and sampling (IPSCS) rate of 87.5% was obtained only after considerable experience had been gained. Sixty-nine patients with CD underwent successful bilateral IPSCS: the IPS-to-peripheral ratio of plasma ACTH value (IPS/P) rose from 9.5 +/- 1.4 to a maximum ratio of 55.8 +/- 7.5 in 67 patients, after CRH stimulation. The maximum ratio was obtained at 5 min in 60 of the 69 patients with CD; however, all 69 patients obtained a ratio of more than 2, at that time. In contrast, the 6 patients with occult ACTH-secreting neoplasms had a maximal IPS/P ratio of 1.3 +/- 0.16, and this did not change after CRH stimulation. A bilateral IPS/P ratio more than 2, obtained 5 min after CRH stimulation, had a sensitivity of 97% and a specificity of 100% in diagnosing CD. Two patients with proven active CD had an IPS/P ratio of less than 2. After successful bilateral IPSCS, the gradients between the IPS ACTH concentrations [IPS ACTH gradient (IPSG)] of more than 1.4, at 5 min after CRH stimulation, had a sensitivity of 83% in correctly lateralizing the pituitary microadenoma, compared with 72% sensitivity for magnetic resonance imaging (MRI) scanning. Furthermore, when IPSG and MRI findings were contradictory, IPSG was more often correct than MRI scanning. Although oEAS is a relatively uncommon cause of ACTH-dependent hypercortisolism (5.5% in our series), the accurate diagnosis of ACTH-dependent CS and localization of an intrapituitary microadenoma requires bilateral IPSCS with CRH stimulation, provided that the appropriate technical experience is available. hCRH is as effective a secretagogue as ovine CRH, and either may be used. The value of the combination of CRH and desmopressin stimulation requires more detailed investigation.

Relative value of computed tomography scanning and venous sampling in establishing the cause of primary hyperaldosteronism.

The purpose of this study was to evaluate the relative merits of the postural stimulation test, adrenal computed tomography (CT) and venous sampling in the differential diagnosis of patients presenting with primary hyperaldosteronism. The records of 20 patients presenting with primary hyperaldosteronism were reviewed retrospectively. There were 15 patients with a unilateral aldosterone-producing adenoma (APA), four patients with idiopathic hyperaldosteronism (IHA) and one patient with primary adrenal hyperplasia (PAH). The postural stimulation test was based on measurements of plasma aldosterone and renin activity at 08.00 h and at noon after 4 h of ambulation. The CT scans of the adrenals were reviewed by a single radiologist. Bilateral venous sampling of adrenal veins was attempted in all patients and blood collected for aldosterone and cortisol assay. Plasma aldosterone concentration increased after 4 h of standing in all cases of hyperplasia but was also demonstrated in 10/15 patients with a surgically-proven APA. If one defines a significant postural rise as being greater than 30%, then 8/15 patients with APA can be considered as being posturally responsive. Computed tomography scanning correctly identified all 15 cases of APA and also classified correctly the remaining five cases of hyperplasia (four cases of IHA and one case of PAH). Venous sampling failed technically in 4/15 cases of APA and in one case of IHA: a total of 5/20 (25%,). A correct diagnosis of APA or IHA was established in all the remaining cases. However, the one case of PAH was treated successfully by adrenalectomy following venous sampling, which suggested a unilateral adrenal lesion: this one result was the only instance where venous sampling altered clinical decision-making. Computed tomography scanning may be used alone to confirm the cause of hyperaldosteronism where postural studies suggest an adrenal adenoma, and such patients may be considered for early surgery. Venous catheterization studies are not necessary routinely. but may still be useful in selected patients, particularly when CT scanning shows no clear lesion.

The "central lucency" sign of lobar dysmorphism (pseudotumour of the kidney).

A proved case of pseudotumour of the kidney due to lobar dysmorphism showed a "central lucency" sign, differentiating this developmental variant from an enlarged column of Bertin. This sign is described in a further case.

Validity of the mean parenchymal transit time as a screening test for the detection of functional renal artery stenosis in hypertensive patients.

Functional significance of renal artery stenosis (RAS) was assessed by 99Tcm-DTPA radionuclide scintigraphy, using the mean parenchymal transit time (MPTT) of the tracer as an index of renovascular disorder. Two groups of subjects were investigated retrospectively: eight normal live kidney donors; and 11 patients with hypertension, six with and five without significant RAS. MPTT was 171 +/- 11 s in the kidney donors, and there was a significantly prolonged MPTT in patients with RAS, 313 +/- 27 s (p less than 0.05). MPTT was also prolonged in three hypertensive patients with intrinsic renal disorders. The advantages and limitations of this technique are discussed. It is concluded that prolongation of MPTT can detect functionally significant renovascular disorder without pharmacological challenge.