Review. Leaky Cl--HCO3- exchangers: cation fluxes via modified AE1

The abundant membrane protein AE1 normally functions as an obligate anion exchanger, with classical carrier properties, in human red blood cells. Recently, four single point mutations of hAE1 have been identified that have lost the anion exchange function, and act as non-selective monovalent cation channels, as shown in both red cell flux and oocyte expression studies. The red cell transport function shows a paradoxical temperature dependence, and is associated with spherocytic and stomatocytic red cell defects, and haemolytic anaemias. Other forms of AE1, including the native AE1 in trout red cells, and the human mutation R760Q show both channel-like and anion exchange properties. The present results point to membrane domains 9 and 10 being important in the functional modification of AE1 activity.

Abnormal permeability pathways in human red blood cells

A number of situations that result in abnormal permeability pathways in human red blood cells (RBCs) have been investigated. In sickle cell disease (SCD), RBCs contain HbS, rather than the normal HbA. When deoxygenated, an abnormal conductance pathway, termed P(sickle), is activated, which contributes to cell dehydration, largely through allowing Ca(2+) entry and subsequent activation of the Gardos channel. Whole-cell patch-clamp recordings from sickle RBCs show a deoxygenated-induced conductance, absent from normal RBCs, which shares some of the properties of P(sickle): equivalent Na(+) and K(+) permeability, significant Ca(2+) conductance, partial inhibition by DIDS and also Zn(2+). Gd(3+) markedly attenuates conductance in both normal and sickle RBCs. In addition, deoxygenated sickle cells, but not oxygenated ones or normal RBCs regardless of the oxygen tension, undergo haemolysis in isosmotic non-electrolyte solutions. Non-electrolyte entry was confirmed radioisotopically whilst haemolysis was inhibited by DIDS. These findings suggest that under certain circumstances P(sickle) may also be permeable to non-electrolytes. Finally, RBCs from certain patients with hereditary stomatocytosis have a mutated band 3, which appears able to act as a conductance pathway for univalent cations. These results extend our understanding of the abnormal permeability pathways of RBCs.

Mild dehydrated hereditary stomatocytosis revealed by marked hepatosiderosis

We report a patient in whom hepatosiderosis was diagnosed at the age of 55 years and who has since been treated by regular bleeding. The H63D mutation was found in the heterozygous state in the HFE gene. No mutation was recorded in the SLC11A3 gene (ferroportin). Hepatosiderosis did not seem primary, nevertheless its cause long remained elusive. Only 2 years ago did we find the responsible condition, a very mildly expressed form of dehydrated hereditary stomatocytosis (DHS). This genetic disease is a strongly iron-loading condition. Haemolysis was fully compensated. Kalaemia was slightly elevated, suggesting a pseudohyperkalaemia that may be associated with DHS. Osmotic gradient ektacytometry allowed to assess the diagnosis of DHS. The red cell monovalent Na+ and K+ concentrations were moderately elevated and reduced respectively. The temperature dependence of the ouabain + bumetanide-resistant K+ influx produced a shallow slope, above and parallel to the control curve. These features were consistent with the diagnosis of DHS. The pronounced hepatosiderosis contrasted with the mildly expressed DHS, and with the ferritinaemia that was slightly elevated, if at all, prior to bleeding. Bleeding caused ferritinaemia to decrease and hepatosiderosis to recede. The whole picture accounts for a misleading presentation of DHS, in which the primary condition long remained hidden behind one of its remotest complications, hepatosiderosis.

Four pedigrees of the cation-leaky hereditary stomatocytosis class presenting with pseudohyperkalaemia. Novel profile of temperature dependence of Na+-K+leak in a xerocytic form

We report four pedigrees of the group of Na(+)-K(+)-leaky red cell disorders of the 'hereditary stomatocytosis' class. Each showed pseudohyperkalaemia because of temperature-dependent loss of K(+) from red cells on storage of whole blood at room temperature. All pedigrees showed an abnormality in the temperature dependence of the 'passive leak' of the membrane to K(+). Two pedigrees, both of which showed a compensated haemolytic state with dehydrated red cells and target cells on the blood film, showed a novel pattern, in which the profile was flat between 37 degrees C and about 32 degrees C then dropped as the temperature was reduced to zero. The third showed the 'shallow slope' profile, with stomatocytes on the blood film and very markedly abnormal intracellular Na(+) and K(+) levels. Minimal haemolysis was present. The fourth pedigree, of Asian origin, showed the shoulder pattern (minimum at 32 degrees C, maximum at 12 degrees C) with essentially normal haematology. Both of these latter two forms have previously been seen in other pedigrees. The first variant represents a novel kind of temperature dependence of the passive leak found in these pedigrees presenting with pseudohyperkalaemia.

A family showing recessively inherited multisystem pathology with aberrant splicing of the erythrocyte Band 7.2b ('stomatin') gene

The case of a French child, born of consanguineous parents of Tunisian origin, is described. He showed a severe multisystem disease with dyserythropoietic, sideroblastic anaemia, delayed neurological development with hypotonia and convulsions, salt-losing nephropathy, chronic watery diarrhoea, lactic acidosis with mitochondrial dysfunction, brittle hair, hypergammaglobulinaemia, fatty liver with intermittent transaminasaemia, and terminal pulmonary fibrosis. Two siblings, of both sexes, were stillborn; two more lived only a short time. One sister is alive and well. SDS gel analysis of the red cell membranes showed a deficiency within 'Band 7' at 32 kDa. Analysis of the gene encoding 'stomatin', or 'erythrocyte membrane protein 7.2b', the principal protein of 'Band 7', revealed a complex series of aberrant spliceforms centred around exon 3, for which no explanatory genomic lesion could be found. The true underlying molecular cause of this condition remains obscure, but it suggests that the stomatin gene should be studied in other cases.

Dehydrated hereditary stomatocytosis with transient perinatal ascites

The case is reported of a mother and baby with dehydrated hereditary stomatocytosis and perinatal ascites, an autosomal dominant condition not previously reported in Britain. Recognition is important for the management of pregnancy and for avoidance of splenectomy which, if performed, can predispose the patient to fatal thromboembolic events.

The curious genomic path from leaky red cell to nephrotic kidney

The human red cell has proved to be an invaluable model cell for the study of many aspects of membrane structure and function. It has a series of transport pathways which mediate the movements of the univalent cations Na and K, which are either identical or similar to systems in other human tissues, including the human kidney. The balance between the energy-consuming NaK pump and a 'passive leak' component maintains a net deficit of cations within the cell, which defends the cell volume against osmotic swelling. There exist a series of dominantly inherited human red cell conditions, gathered under the generic title 'hereditary stomatocytoses', in which the so-called 'passive leak' to Na and K is pathologically increased. In the more severe variants this compromises the integrity of the cell and the patients suffer haemolytic anaemia. Some less severe variants present with pseudohyperkalaemia caused by loss of K from red cells on storage of blood at room temperature. The most severe variants show a deficiency in a widely distributed 'raft' protein known as stomatin. The stomatin protein is homologous to the 'podocin' protein, the gene for which is mutated in a recessively inherited form of nephrotic syndrome. Among other possible functions, both proteins could be involved in the trafficking of membrane proteins to and from the plasma membrane.

Allogeneic bone marrow transplantation for severe post-splenectomy thrombophilic state in leaky red cell membrane haemolytic anaemia of the stomatocytosis class

The tendency for thrombosis to occur if haemolysis persists after splenectomy is especially marked in "hereditary stomatocytosis", in which the red cell membrane "leaks" Na and K. A 21-year-old woman, who was splenectomized in childhood for a congenital haemolytic state, presented with major pulmonary embolism that recurred despite anticoagulation. Tests showed a significant cation leak with a "shallow-slope" abnormality in temperature dependence. Allogeneic bone marrow transplantation caused the thrombophilic state to cease and subsequently anticoagulation was stopped without recurrence of thromboembolism. However, she died 9 months after transplantation: iron overload, intensified by the transfusion demands of the transplant, was a major factor.

ATP-dependent vesiculation in red cell membranes from different hereditary stomatocytosis variants

The hereditary stomatocytoses are a group of dominant haemolytic anaemias that show two main features: invaginated, 'stomatocytic' morphology; and a membrane leak to the univalent cations Na and K. A patient with the most severe variant of these conditions was reported to show a defect in an in vitro process of ATP-dependent endocytic vesiculation (ADEV), which is found in normal red cells. We have examined this endocytosis process in 11 leaky red cell pedigrees available to us in the UK. ADEV in broken membranes was absent only in the two most severely affected, 'overhydrated' pedigrees studied, both of which showed a deficiency in the membrane raft protein, stomatin. The process was present, although typically diminished by about 10-20% compared with normal red cells, in all others. The cross-linker dimethyl adipimate (DMA), which could correct the cation leak in some of these patients, also corrected the ADEV defect in the same patients. In those patients in whom DMA had no effect on the ion leak, ADEV was not absent. In normal cells, this process of vesiculation was inhibited by inhibitors of membrane 'raft' function, by an antistomatin antibody and by vanadate and N-ethyl maleimide, but not by inhibitors of a number of kinases. These data highlight the heterogeneity of these conditions. A mechanism is discussed by which a defect in raft-based endocytosis could lead to the exaggerated surface exposure of an ion channel, which could then function constitutively, i.e. 'leak'.

Two further British families with the 'cryohydrocytosis' form of hereditary stomatocytosis

We describe two families with the 'cryohydrocytosis' form of stomatocytosis. Both show a mild stomatocytic anaemia with Hb levels of 12-16 g/dl and reticulocyte counts of 4.3-24%, with very marked autohaemolysis at refrigerator temperatures and pseudohyperkalaemia as a result of loss of K from red cells on storage at room temperature. The ouabain + bumetanide-insensitive 'passive leak' K influx showed a 'U'-shaped temperature dependence, with a minimum at 23 degrees C. In one family, there was consistent variation in haematological severity within the pedigree. In the other, the parents of the proposita were normal, but all three of her children were affected, consistent with a new mutation of a dominant condition. Cold storage of the red cells led to a very marked increase in osmotic fragility and macrospherocytosis, explaining why a diagnosis of 'hereditary spherocytosis' can easily be reached in these pedigrees.

Pseudohyperkalaemia and pseudomacrocytosis caused by inherited red-cell disorders of the 'hereditary stomatocytosis' group

Unusual dominantly inherited conditions of the red cell, collected under the generic title 'hereditary stomatocytosis and allied disorders', exist, in which the red cell 'leaks' the univalent cations sodium (Na+) and potassium (K+). In some kindreds with these disorders, bizarre temperature effects can occur that have profound effects on the way in which the cells behave when removed from the body and cooled to either room or refrigerator temperatures. In some types, the cells lose K+ at room temperature, giving rise to pseudohyperkalaemia; in others, this occurs in concert with swelling of the red cell and pseudomacrocytosis. In some of these conditions, a red-cell abnormality is clearly demonstrated by the presence of haemolytic anaemia; however, routine haematology can be virtually normal in the milder versions. All are inherited as dominants, although new mutations can be seen.

Familial pseudohyperkalaemia Chiswick: a novel congenital thermotropic variant of K and Na transport across the human red cell membrane

Two families with inherited abnormalities in Na and K transport across the red cell membrane are described. Both presented with 'pseudohyperkalaemia' as a result of loss of K from the red cells on storage at room temperature. Routine haematology was essentially normal, except for macrocytosis in one family. Studies of the temperature dependence of the passive leak to K showed a novel shoulder pattern with a minimum at 25 degrees C, a maximum at 10 degrees C, followed by a further fall. As in other cases of red cell-based pseudohyperkalaemia, the abnormal temperature dependence of this 'leak' flux could be held to account for the loss of K from the cells at room temperature. These cases represent a novel variant of the temperature dependence of the passive leak of K and Na across the red cell membrane, and can be classified as a mild, non-haemolytic form of the group known as the hereditary stomatocytosis and allied disorders'.

Pleiotropic syndrome of dehydrated hereditary stomatocytosis, pseudohyperkalemia, and perinatal edema maps to 16q23-q24

Dehydrated hereditary stomatocytosis (DHS) is a rare genetic disorder of red cell permeability to cations, leading to a well-compensated hemolytic anemia. DHS was shown previously to be associated in some families with a particular form of perinatal edema, which resolves in the weeks following birth and, in addition, with pseudohyperkalemia in one kindred. The latter condition was hitherto regarded as the separate entity, "familial pseudohyperkalemia." DHS and familial pseudohyperkalemia are thought to stem from the same gene, mapping to 16q23-q24. This study screened 8 French and 2 American families with DHS. DHS appeared to be part of a pleiotropic syndrome in some families: DHS + perinatal edema, DHS + pseudohyperkalemia, or DHS + perinatal edema + pseudohyperkalemia. If adequately attended to, the perinatal edema resolved spontaneously after birth. Logistic regression showed that increased mean corpuscular volume and mean corpuscular hemoglobin concentration were the parameters best related to DHS. In patients in whom cation fluxes were investigated, the temperature dependence of the monovalent cation leak exhibited comparable curves. Specific recombination events consistently suggested that the responsible gene lies between markers D16S402 and D16S3037 (16q23-q24). The 95% confidence limits (Z(max) >/= 3.02) spanned almost the complete 9-cM interval between these 2 markers.

Effect of dimethyl adipimidate on K+ transport and shape change in red blood cells from sickle cell patients

Dimethyl adipimidate (DMA) reduces K+ loss from, and dehydration of, red cells containing haemoglobin S (HbS cells). Three membrane transporters may contribute to these processes: the deoxygenation-induced cation-selective channel (Psickle), the Ca2+-activated K+ channel (or Gardos channel) and the K+-CI- cotransporter (KCC). We show that DMA inhibited all three pathways in deoxygenated HbS cells. The Gardos channel could be activated following Ca2+ loading. Considerable KCC activity was present in oxygenated HbS cells, showing a selective action of DMA on the transporter in deoxygenated cells. Inhibition of sickling correlated strongly with that of Psickle and moderately with that of KCC activity. We conclude that DMA does not inhibit the K+ pathways directly, but acts mainly by preventing HbS polymerisation and sickling. These findings are relevant to the development of novel chemotherapeutic agents for amelioration of sickle cell disease.

Evolutionary exploitation of design options by the first animals with hard skeletons

The set of viable design elements available for animals to use in building skeletons has been fully exploited. Analysis of animal skeletons in relation to the multivariate, theoretical "Skeleton Space" has shown that a large proportion of these options are used in each phylum. Here, we show that structural elements deployed in the skeletons of Burgess Shale animals (Middle Cambrian) incorporate 146 of 182 character pairs defined in this morphospace. Within 15 million years of the appearance of crown groups of phyla with substantial hard parts, at least 80 percent of skeletal design elements recognized among living and extinct marine metazoans were exploited.

The hereditary stomatocytoses and allied disorders: congenital disorders of erythrocyte membrane permeability to Na and K

The hereditary stomatocytoses and allied disorders are a set of dominantly inherited haemolytic anaemias in which the plasma membrane of the red cell 'leaks' sodium and potassium. There are about 10 different forms of these conditions, ranging from a moderately severe haemolytic anaemia to minor conditions in which the haematology is essentially normal, but where the patients present with pseudohyperkalaemia, due to leakage of K from the red cells on cooling to room temperature. Frequently misdiagnosed as atypical hereditary spherocytosis, these conditions can show marked thrombotic complications after splenectomy, which should be avoided. Laboratory studies of these conditions have drawn attention to a 32 kDa membrane protein, stomatin, which seems to act as a regulator of Na and K transport in human and animal tissues generally, but mutations in this gene do not cause these diseases. Genetic mapping in some kindreds, but not all, points to a mutation locus on chromosome 16.

Subjective swelling: a new sign for carpal tunnel syndrome

This single-blinded, randomized cohort study of 186 patients was conducted to determine whether the subjective complaint of swelling of the hand or wrist is associated with the diagnosis and/or prognosis of carpal tunnel syndrome. All patients were referred for splinting with a presenting clinical diagnosis of carpal tunnel syndrome from outpatient specialty clinics, including orthopedics, rheumatology, and neurology. Patients were assessed before splinting for the complaint of subjective swelling and underwent a clinical examination including Phalen testing and carpal compression testing. In addition, 211 of the 290 joints underwent electrodiagnostic testing by the end of this study. Among the 211 joints for which electrodiagnosis was used, a chi2 analysis was performed to determine the correlation among subjective swelling, the Phalen and carpal compression tests, and the electrodiagnostically verified carpal tunnel syndrome. Two weeks after splinting, an assessment was made of the subjective response to splinting. Chi2 analysis was then performed to assess the correlation among the Phalen test, carpal compression test, and nerve conduction study results and the symptom of subjective swelling at presentation with that of response to splinting. Subjective swelling of the hand showed a trend toward association with electrodiagnostic results (although this finding was not statistically significant) and proved to be significantly correlated with a poor clinical response to splinting. Positive electrodiagnostic findings were significantly, though positively, correlated with pain relief from splinting. This study, therefore, introduces the complaint of subjective swelling of the affected hand as an important diagnostic and prognostic symptom for the assessment and treatment of carpal tunnel syndrome.

Two British families with variants of the 'cryohydrocytosis' form of hereditary stomatocytosis

We describe two British families with similar, dominantly-inherited, temperature-related variants of hereditary stomatocytosis, consistent with the original description of 'cryohydrocytosis'. The cells show a 5-6-fold increase in passive permeability at 37 degrees C with abnormal intracellular Na and K levels at 15-20 and 60-65 mmol/(l cells) respectively. Marked temperature effects were evident: lysis of red cells on storage in the cold was blatant and when whole heparinized blood was stored at room temperature, K accumulated in the plasma, producing 'pseudohyperkalaemia'. Studies of the temperature dependence of passive permeability showed that the minimum in the passive permeability, which is seen in normal cells at 8-10 degrees C, was shifted up to 23 degrees C in these abnormal cells, such that the permeability at 0 degrees C exceeded that at 37 degrees C. The abnormal temperature dependence in these genetically abnormal red cells strongly resembles that seen in normal cells when suspended in media in which either Na or Cl has been replaced by an organic cation or anion: it could be said these cells had a genetic mutation that somehow rendered the cell resistant to the stabilizing action of NaCl at low temperatures.

Familial pseudohyperkalemia maps to the same locus as dehydrated hereditary stomatocytosis (hereditary xerocytosis)

Familial pseudohyperkalemia is a "leaky red blood cell" condition in which the cells show a temperature-dependent loss of potassium (K) from red blood cells when stored at room temperature, manifesting as apparent hyperkalemia. The red blood cells show a reduced lifespan in vivo but there is no frank hemolysis. Studies of cation content and transport show a marginal increase in permeability at 37 degrees C and a degree of cellular dehydration, qualitatively similar to the changes seen in dehydrated hereditary stomatocytosis (hereditary xerocytosis). Physiological studies have shown that the passive leak to K has an abnormal temperature dependence, such that the leak is less sensitive to temperature than that in normal cells. We performed genetic mapping on the original family and found that the condition in this kindred maps to the same locus (16q23-ter) that we have previously identified for an Irish family with dehydrated hereditary stomatocytosis, which does not show the same temperature effects.

A variant of hereditary stomatocytosis with marked pseudohyperkalaemia

A family with an unusual form of hereditary stomatocytosis is described. The affected members showed a mild, dominantly-inherited, haemolytic anaemia with intracellular Na and K levels of 41-48 and 44-53 mmol/(l cells) respectively. This anaemia was associated with marked 'pseudohyperkalaemia': that is, loss of K from red cells on storage at room temperature. At 37 degrees C, 'leak' tracer flux rates (assessed as the ouabain + bumetanide-resistant K fluxes) showed a roughly 5-fold acceleration compared to normal, and an abnormal temperature dependence with a shallow slope between 37 and 20 degrees C (mean Q10 (ratio of reaction rates at temperature T and T - 10) over this interval, 1.6; normal 2.2). The pseudohyperkalaemia could be attributed to the disparity between pump and leak at 20 degrees C. This is an identical mechanism to that previously shown for the haemato logically trivial condition, 'familial pseudohyperkalaemia. No protein or lipid abnormality was found in the membrane of these cells.

Utilization of an 86 bp exon generates a novel adducin isoform (beta 4) lacking the MARCKS homology domain

A novel isoform of beta-adducin has been amplified and characterized from a human bone marrow cDNA library (GenBank #U43959). This isoform arises from the insertion of an 86 bp alternatively spliced and previously unrecognized exon (now termed exon 15) within codon 581 of the human red blood cell beta-adducin sequence. This results in an insertion of 28 novel amino acids. The remainder of the red cell beta-adducin mRNA is then translated in a different reading frame, adding an additional 35 novel amino acids prior to the stop codon. This new isoform, thus, replaces beta 1-adducin sequence after residue 580 with a total of 63 new amino acids. Sequences from genomic clones of the human beta-adducin gene show that this alternate exon is flanked by splice consensus sequences and is appropriately located in the genomic map between exons encoding up-stream and down-stream sequences, thus defining a new exon. The COOH-terminus of this new isoform, which we designate beta 4, lacks a 22 amino acid lysine-rich sequence common to both the human red cell alpha- and beta-adducin subunits and homologous to a highly conserved region in MARCKS, a filamentous actin-cross linking protein regulated by protein kinase C and calcium/calmodulin. beta 4-adducin preserves a previously identified calmodulin binding domain. PCR analysis indicates that this new beta-adducin isoform is expressed in fetal brain and liver, bone marrow, and NT-2 (neuroepithelial) cells, but is not detected in several other tissues. We anticipate that this new beta 4 isoform of beta-adducin will display unique and tissue-specific functional properties.

Evaluation of a program of university placement for spinal cord injured rehabilitation clients in Louisiana

The Louisiana State Department of Social Services, Rehabilitation Services (LRS) offers a program of financial support for spinal cord injured persons to attend college. We evaluated this program's effectiveness and attempted to identify factors that may predict student success. We examined the LRS case records of all students with documented SCI who had enrolled in the LRS college program before 1988. We compared the proportion of LRS clients who graduated with the proportion of general population students attending the same schools. We measured the association between graduation and factors that may help predict success. Of the 51 LRS clients studied, 25 (49%) graduated from baccalaureate institutions within 6 years. Of Louisiana students-at-large who attended the colleges that housed LRS students, 36% of those graduated within 6 years. The best predictor of success was the American College Test score. All students with a score of 17 or more graduated. A larger proportion of LRS-sponsored students graduated than did students from the general population.

Stomatin

Stomatin is a 31-kDa integral membrane protein, named after the rare human haemolytic anaemia hereditary stomatocytosis. In some cases of this anaemia, in which the red cells leak sodium and potassium ions, this protein is absent from the membrane, immediately suggesting that it has a role in the regulation of ion transport. The protein has a single hydrophobic domain, presumed to be membrane-associated, is phosphorylated, and is widely distributed in animal tissues. Mutations of a homologue in sensory nerve cells of the nematode Caenorhabditis elegans disrupt a neuronal transduction mechanism, in which mechanosensory information is relayed to an ion channel, whose opening initiates an action potential. It could be that this protein is a molecular link in a genetic stretch-sensitive system. Abnormalities of red cell ion transport are well known in human hypertension, but the molecular basis has never been elucidated: this protein and its functional associates, operating in a stretch- or pressure-sensitive complex, might be important.

High school football-related cervical spinal cord injuries in Louisiana: the athlete's perspective

Louisiana has one of the highest rates in the nation of cervical spinal cord injuries to high school football players. When the national rate of these injuries is applied to the number of high school participants in Louisiana, we would expect there to be only one catastrophic neck injury every 14 years. Louisiana, however, has averaged 2.3 spinal cord injuries per year for the past seven football seasons. Players who use the top of their helmets to tackle, block, or strike opponents are at greatest risk for these injuries. This study was undertaken to describe the safe tackling knowledge, attitudes, and practices of Louisiana high school football players. We surveyed 596 players from 16 Louisiana high schools. When asked if it was within the rules to tackle anyone by using the top of their helmet, 29% incorrectly answered "yes". Similarly, when asked if they had ever tackled anyone using the top of their helmet, 33% reported that they had. Twenty-eight percent said that they had been taught to use this unsafe method. Of these, 83% said that their coach taught them this dangerous and illegal method. Using the helmet as a battering ram must be discouraged. Education for officials, coaches, and players is needed to improve recognition of improper tackling. Proper training in tackling and blocking is an important means of minimizing the possibility of catastrophic injury.

Thrombo-embolic disease after splenectomy for hereditary stomatocytosis

Nine cases of hereditary stomatocytosis (HSt) are presented which show documented thrombotic complications after splenectomy. In three cases, patients became severely ill with pulmonary hypertension and a fourth developed portal hypertension. One unsplenectomized affected adult relative had suspected but unconfirmed thrombotic pathology; the six other affected unsplenectomized adults did not. Since splenectomy is of only limited therapeutic benefit in stomatocytosis, it should not be performed without careful consideration. A tendency to iron overload, even without hypertransfusion and irrespective of splenectomy, is evident in many of these patients.

Continuities between psychiatric disorders in adolescents and personality disorders in young adults

OBJECTIVE

Personality disorders are a major mental health problem, but little information about their etiology and natural history is available. This study examined continuities between axis I disorders in adolescents and personality disorders in young adults.

METHOD

The authors interviewed 145 young adults (mean age, 19.6 years) who had been diagnosed with a variety of DSM-III emotional and disruptive disorders during adolescence (mean age, 13.7 years). The Personality Disorder Examination was used to establish whether the subjects currently suffered from personality disorders.

RESULTS

Subjects who had had disruptive disorders during adolescence showed high rates of all types of personality disorders (40% had a personality disorder at follow-up), while subjects who had had emotional disorders had a lower rate of personality disorders (12%). Men were more likely to have cluster A personality disorders, and women were more likely to have cluster C personality disorders. Disruptive diagnoses were associated with cluster B personality disorders, but emotional disorders did not show an association with cluster C personality disorders. Oppositional disorder did not increase the likelihood of passive-aggressive personality disorder. There was an association between attention deficit disorder with hyperactivity and borderline personality disorder.

CONCLUSIONS

The rate of personality disorders was lower among young adults who had had emotional disorders during adolescence than among those who had had disruptive disorders, suggesting either that treatment for emotional disorders is more effective or that the personality psychopathology in these adolescents is not as severe as that in adolescents with disruptive disorders.

Sports medicine in physical medicine and rehabilitation residency programs

Because sports medicine is a rapidly expanding field within many specialties, it is important to gauge how active physiatrists have become in this arena. A nationwide survey of program directors and chief residents of physical medicine and rehabilitation residency programs was conducted to determine such prevalence. For the purposes of this study, sports medicine was defined as the routine care of athletes involved in organized sporting activities at any level of competition. Questionnaires were mailed to program directors and chief residents with response rates of 79.7% each. Overall, correlation of the answers between groups was high. The level of interest of residents was rated at 46%. Data was also obtained regarding research, clinical rotations, lectures, fellowships, association with academic departments of other specialties, and affiliations with professional sports medicine organizations. The actual level of educational opportunities available was much lower than might be expected given the high level of interest expressed. It is reasonable to conclude that more opportunities should exist for education in sports medicine.

Splinting for carpal tunnel syndrome: in search of the optimal angle

Carpal tunnel syndrome (CTS) is the most common of the compression neuropathies. Several studies have demonstrated the efficacy of wrist splinting in relieving the symptoms of CTS; however, the chosen angle of immobilization has varied. Wick catheter measurements of carpal tunnel pressures suggest that the neural position has less pressure and, therefore, greater potential to provide relief from symptoms. This study is a prospectively gathered, blind trial comparing the symptom relief experienced by wearers of splints immobilized at 20 degrees extension and at neutral. The results indicate that the neutral angle provided superior symptom relief, and that the relief did not often improve between 2 weeks and 2 months of wear. Relief of symptoms was not related to the length of time that the patient had experienced of CTS symptoms. The results also indicate that the results of the electromyography/nerve conduction study (EMG/NCS) do not provide information about the subjects' likely response to splinting.

Paraplegia in a patient with Marfan's syndrome as a result of a thoraco-abdominal aortic aneurysm repair

Marfan's syndrome is a hereditary disorder involving a deficit in connective tissue collagen. Physical findings include musculoskeletal, ocular, and cardiovascular abnormalities. A 29-year-old man with a history of Marfan's syndrome was admitted to the hospital with back and chest pain secondary to a dissecting aortic aneurysm. He later underwent surgical aortic bypass graft surgery. Postoperatively, he was paraplegic. Our impression was anterior spinal artery syndrome due to prolonged cross-clamping of the aorta during surgical repair. This paper shows the risk of paralysis resulting from surgical repair of an aortic aneurysm as a poorly documented complication of Marfan's syndrome.

Serum potassium, hydrogen ion and magnesium: neuromuscular regulation by variation of cation concentration in the extracellular fluid?

It is a common clinical observation that changes in serum [K] are frequently associated with changes in serum [H] and/or [Mg]. Thus, hypokalaemia and alkalosis are associated, as are hyperkalaemia and acidosis, and hypokalaemia and hypomagnesaemia. Most investigators would accept that these ions have important roles in the maintenance of neuromuscular excitability. Extracellular potassium exerts its effect by defining the potassium gradient across the cell membrane and therefore the membrane potential in the resting state; magnesium and hydrogen ion 'screen' negative charges on the surface of nerve cells, modulating the local transmembrane potential gradient, to which the voltage-sensitive channels governing the initiation of the action potential respond. It is pointed out here that the changes in ionic concentration observed in pathophysiology are not incompatible with the idea that the associated changes reflect regulatory events in the extracellular fluid designed to preserve excitability.

The membrane defect in hereditary stomatocytosis

Hereditary stomatocytosis and allied conditions represent a series of diseases in which abnormal movements of univalent cations across the plasma membrane play an important part in cellular disease. The primary problem lies not in the active transporters but in the basal permeability of the membrane, which is always increased, and the extent of the increase correlates with the cellular dysfunction. A number of structural abnormalities have been described in these membranes, but the most consistent and convincing is the deficiency of a hitherto uncharacterized integral membrane protein of molecular weight 31 kDa in the severe, 'overhydrated' form of the disease. The true function of this protein remains enigmatic, but its deficiency in this condition indicates that it may have a role in the regulation of cation transport.

Effect of high voltage pulsed galvanic stimulation on sacral transcutaneous oxygen tension levels in the spinal cord injured

Evidence is mounting that spinal cord injured (SCI) persons may be at increased risk of pressure ulcers due to prolonged immobilization together with the injury-induced loss of sympathetic tone and decreased vascular resistance. With a view to developing a new method of preventing pressure ulcers, the objective of this study was to determine whether high voltage pulsed galvanic stimulation (HVPGS) could increase sacral transcutaneous oxygen tension (PtcO2) in SCI persons lying prone and supine. In experiment 1, HVPGS applied to the back at spinal level T6 led to a sustained, dose-related increase in sacral PtcO2 in 3 subjects lying prone. In experiment 2, carried out on 29 subjects lying supine on egg-crate mattresses, HVPGS (75 volts, 10 Hz) produced a 35% increase in sacral PtcO2, from a baseline level (Mean +/- SD) of 49 +/- 21 mmHg to 66 +/- 18 mmHg after 30 minutes of stimulation (F = 39.4, p < .00001). In experiment 3, simulated HVPGS was found to have no effect on sacral PtcO2 in 5 subjects lying supine. In experiment 4, HVPGS was repeated on 10 subjects and its effects found to be highly reproducible. It is hypothesized that HVPGS restores sympathetic tone and vascular resistance below the level of the spinal cord lesion, thereby increasing the perfusion pressure gradient in the capillary beds. Randomized controlled trials are now indicated to determine the efficacy of HVPGS for preventing pressure ulcers.