The effect of superpulsed carbon dioxide laser energy on keloid and normal dermal fibroblast secretion of growth factors: a serum-free study

An in vitro model was used to determine the effect of superpulsed CO2 laser energy on normal dermal and keloid-producing fibroblast proliferation and release of growth factors. Growth factors assayed included basic fibroblast growth factor (bFGF) and transforming growth factor beta1 (TGF-beta1). bFGF is mitogenic, inhibits collagen production, and stabilizes cellular phenotype. TGF-beta1 stimulates growth and collagen secretion and is thought to be integral to keloid formation. Growth in a serum-free medium allowed measurement of these growth factors without confounding variables. Keloid and normal dermal fibroblasts cell lines were established from facial skin samples using standard explant techniques. Samples consisted of three separate keloid and three separate normal dermal fibroblast cell lines. Cells were used at passage 4 to seed 24-well trays at a concentration of 6 x 10(4) cells per milliliter in serum-free medium. At 48 hours, 18.8 percent of each cell well was exposed to a fluence of 2.4, 4.7, and 7.3 J/cm2 using the superpulsed CO2 laser. Cell viability and counts were established at four time points: 0 (time of superpulsed CO2 laser treatment), 24, 72, and 120 hours. Supernatants were collected and assessed for bFGF and TGF-beta1 using a sandwich enzyme immunoassay. All cell lines demonstrated logarithmic growth through 120 hours (conclusion of experiment), with a statistically significant shorter population doubling time for keloid fibroblasts (p < 0.05). Use of the superpulsed CO2 laser shortened population doubling times relative to that of controls; the differences were statistically significant in keloid dermal fibroblasts when fluences of 2.4 and 4.7 J/cm2 were used (p < 0.05 and 0.01, respectively). bFGF was present in greater levels in normal dermal fibroblasts than in keloid dermal fibroblasts. Application of superpulsed CO2 demonstrated a trend toward increased bFGF secretion in both fibroblast types; the increase was significant in the keloid group at 4.7J/cm2. A consistent trend in suppression of TGF-beta1 was seen in both groups exposed to superpulsed CO2, with the maximal effect occurring at 4.7 J/cm2. Serum-free culture sustains logarithmic cell growth and allows growth factor measurement without confounding variables from serum-containing media. Superpulsed CO2 enhances fibroblast replication and seems to stimulate bFGF secretion and to inhibit TGF-beta1 secretion. Given the function of these growth factors, the application of superpulsed CO2 may support normalized wound healing. These findings may explain the beneficial effects of laser resurfacing on a cellular level and support the use of superpulsed CO2 in the management of keloid scar tissue.

Dysregulated hematopoiesis and a progressive neurological disorder induced by expression of an activated form of the human common beta chain in transgenic mice

Previously we described activating mutations of hbetac, the common signaling subunit of the receptors for the hematopoietic and inflammatory cytokines, GM-CSF, IL-3, and IL-5. The activated mutant, hbetacFIDelta, is able to confer growth factor-independent proliferation on the murine myeloid cell line FDC-P1, and on primary committed myeloid progenitors. We have used this activating mutation to study the effects of chronic cytokine receptor stimulation. Transgenic mice were produced carrying the hbetacFIDelta cDNA linked to the constitutive promoter derived from the phosphoglycerate kinase gene, PGK-1. Transgene expression was demonstrated in several tissues and functional activity of the mutant receptor was confirmed in hematopoietic tissues by the presence of granulocyte macrophage and macrophage colony-forming cells (CFU-GM and CFU-M) in the absence of added cytokines. All transgenic mice display a myeloproliferative disorder characterized by splenomegaly, erythrocytosis, and granulocytic and megakaryocytic hyperplasia. This disorder resembles the human disease polycythemia vera, suggesting that activating mutations in hbetac may play a role in the pathogenesis of this myeloproliferative disorder. In addition, these transgenic mice develop a sporadic, progressive neurological disease and display bilateral, symmetrical foci of necrosis in the white matter of brain stem associated with an accumulation of macrophages. Thus, chronic hbetac activation has the potential to contribute to pathological events in the central nervous system.

Grafts of genetically modified Schwann cells to the spinal cord: survival, axon growth, and myelination

Schwann cells naturally support axonal regeneration after injury in the peripheral nervous system, and have also shown a significant, albeit limited, ability to support axonal growth and remyelination after grafting to the central nervous system (CNS). It is possible that Schwann cell-induced axonal growth in the CNS could be substantially increased by genetic manipulation to secrete augmented amounts of neurotrophic factors. To test this hypothesis, cultured primary adult rat Schwann cells were genetically modified using retroviral vectors to produce and secrete high levels of human nerve growth factor (NGF). These cells were then grafted to the midthoracic spinal cords of adult rats. Findings were compared to animals that received grafts of nontransduced Schwann cells. Spinal cord lesions were not placed prior to grafting because the primary aim of this study was to examine features of grafted Schwann cell survival, growth, and effects on host axons. In vitro prior to grafting, Schwann cells secreted 1.5+/-0.1 ng human NGF/ml/10(6) cells/day. Schwann cell transplants readily survived for 2 wk to 1 yr after in vivo placement. Some NGF-transduced grafts slowly increased in size over time compared to nontransduced grafts; the latter remained stable in size. NGF-transduced transplants were densely penetrated by primary sensory nociceptive axons originating from the dorsolateral fasciculus of the spinal cord, whereas control grafts showed significantly fewer penetrating sensory axons. Over time, Schwann cell grafts also became penetrated by TH- and DBH-labeled axons of putative coerulospinal origin, unlike control cell grafts. Ultrastructurally, axons in both graft types were extensively myelinated by Schwann cells. Grafted animals showed no changes in gross locomotor function. In vivo expression of the human NGF transgene was demonstrated for periods of at least 6 m. These findings demonstrate that primary adult Schwann cells 1) can be transduced to secrete augmented levels of neurotrophic factors, 2) survive grafting to the CNS for prolonged time periods, 3) elicit robust growth of host neurotrophin-responsive axons, 4) myelinate CNS axons, and 5) express the transgene for prolonged time periods in vivo. Some grafts slowly enlarge over time, a feature that may be attributable to the propensity of Schwann cells to immortalize after multiple passages. Transduced Schwann cells merit further study as tools for promoting CNS regeneration.

Cancer-related thromboembolic disease in patients with solid tumours: a retrospective analysis

BACKGROUND

Cancer patients frequently suffer thromboembolic events. This study assessed the incidence and resource implications of cancer-related thromboembolic disease (CTD) in a single, large cancer centre.

PATIENTS AND METHODS

A retrospective analysis of patients admitted with CTD and/or the complications of treatment of CTD over a two-year period has been conducted. Forty-eight patients (23 male, 25 female, median age 60 years) with a variety of solid tumours were identified.

RESULTS

The initial presentations were venous thromboses (28 patients) and pulmonary embolism (20 patients). The median interval from cancer diagnosis to the initial episode of CTD was eight (range 0-112) months. Twenty-two patients suffered additional thromboses, despite maintenance warfarin anticoagulation in 18 patients. Six patients experienced anticoagulation-induced haemorrhage. Forty-one (85.4%) patients have died. The median survival from the first thromboembolic event was 8.5 months. The median inpatient stay for management of the first event was 10 (range 4-75) days, accounting for 729 inpatient days during the study period. Recurrent episodes of CTD or complications of anticoagulation resulted in 28 readmissions, accounting for 295 inpatient days. During the two-year period 1024 inpatient days were directly caused by CTD and its complications, representing 6.1% bed occupancy on our unit.

CONCLUSION

This study demonstrates that CTD represents a significant cause of morbidity in cancer patients with considerable resource implications for cancer centres. Improvements in prevention and management of CTD would reduce morbidity and lead to considerable cost savings.

IAIMS and sharing

The Integrated Academic Information Management System (IAIMS) concept is about sharing resources and information, and about improving the decision-making ability of health care professionals by integrating information. At Columbia-Presbyterian Medical Center, the IAIMS project has established an information architecture based on common, shared computing and networking resources. The institutional computing culture has been changed with increased sharing of information and, consequently, improved quality of information. Several classes of information in the areas of clinical, scholarly, administrative, basic research, and core resources have been identified for better understanding of information responsibility. Technical problems such as heterogeneity on workstation platforms and lack of universal syntactic and semantic standards for health care information exchange still impede inter-institutional sharing of information.

Importance of tonicity of carbicarb on the functional and metabolic responses of the acidotic isolated heart

In this study, the physiological and metabolic effects of Carbicarb administered as an isotonic (150 mmol/L Na[n[]I+) or hypertonic (1 mol/L Na[n[]I+) solution over 2 minutes in the acidotic isolated heart were compared. Physiological monitoring as well as 31P and 23Na nuclear magnetic resonance spectroscopy were performed. Both isotonic and hypertonic Carbicarb induced comparable dose-dependent increases in intracellular pH as well as decreases in inorganic phosphate and increases in creatine phosphate concentrations, which were sustained for 20 minutes. However, immediate functional improvement was greater in hearts receiving isotonic Carbicarb. Metabolic acidosis conditions resulted in a 27% increase in cytosolic sodium by 30 minutes (P < .05). In this setting, hypertonic Carbicarb induced a large transient increase in cytosolic sodium, whereas isotonic Carbicarb caused immediate and sustained decreases in cytosolic sodium. These data suggest that isotonic Carbicarb may have more beneficial effects on cardiac function than hypertonic Carbicarb. These effects may be related to associated changes in cytosolic sodium.

Leak point of incontinence: a measure of the interaction between outlet resistance and bladder capacity

A total of 48 consecutive spina bifida patients undergoing routine urodynamic studies was classified into 2 groups depending upon whether they demonstrated uninhibited bladder contractions. Of the patients 34 demonstrated detrusor hyperreflexia and 14 had detrusor areflexia. These 2 groups were then subdivided depending on the continence status. Of the areflexic and hyperreflexic groups, 6 and 7 patients, respectively, were wet despite at least 2 years of conservative medical management. Leak point pressure and leak point volume were determined in all patients and results were compared in both subgroups. In the hyperreflexic groups leak point volume but not leak point pressure was significantly different between the wet and dry patients. The areflexic group demonstrated the opposite finding, that is the leak point pressure but not the leak point volume was significantly different between wet and dry patients. From these studies we determined that in the areflexic group leak point pressure was useful to predict incontinence, whereas in the hyperreflexic group leak point volume was more useful. The addition of the measurement of leak point pressure and leak point volume during routine urodynamic studies in myelodysplastic patients enhances accurate diagnosis and may select those who will best benefit from bladder augmentation and/or a procedure to increase outlet resistance.

The role of sigmoidoscopy in the management of gunshot wounds to the buttocks

The charts of all patients (n = 70) admitted over 26 months after sustaining a gunshot wound to the buttocks were reviewed to assess the role of physical examination, routine radiologic studies, and sigmoidoscopy in the evaluation of these patients. There were 68 men and 2 women. Sixteen patients underwent sigmoidoscopy, which demonstrated a rectal injury in 7. Six of these patients had other abnormalities on either physical examination or plain pelvic radiographs that would have otherwise led to operation. There were no missed injuries and no morbidity in the remaining patients that were managed without sigmoidoscopy. Indications for sigmoidoscopy were gross blood on rectal examination in 2, bullet path with proximity to the rectum in 13, and persistent abdominal pain in 1. All patients with gross blood on rectal examination (n = 5) and blood at the urethral meatus (n = 2) had visceral injuries. One patient underwent celiotomy for an injury at 15 cm that was noted on sigmoidoscopy performed because the bullet trajectory was in proximity to the rectum. Sigmoidoscopy can be performed selectively in patients sustaining a gunshot wound to the buttocks when the proximity of the wound to the rectum is in doubt.

"No stent, no diversion" Mathieu hypospadias repair

The Mathieu procedure is a surgical technique for anterior hypospadias repair. The disadvantage of this technique is the prolonged hospital stay associated with postoperative urinary diversion. In an effort to reduce the length of hospital stay the authors carried out a prospective study to determine the usefulness of urethral stents and urinary diversion after Mathieu repair. Seventeen boys (mean age 4.1 years) formed the experimental group, and 19 boys (mean age 4.6 years) served as controls. Urinary diversion and urethral stents were used postoperatively in the control group but not in the experimental group. After a minimum of 6 months of observation the complications noted in both groups were found to be similar. The authors conclude that urinary diversion and urethral stents have no beneficial effects on surgical outcome but do prolong hospital stay.

Multiple trkA proteins in PC12 cells bind NGF with a slow association rate

Rat pheochromocytoma (PC12) cells express two distinct nerve growth factor receptors (NGFRs), p75NGFR and trkA (p140trk). In addition to these receptors, by using 125I-mNGF affinity labeling and BS3 chemical cross-linking of PC12 cell protein, we have identified two additional trkA protein bands with apparent molecular weights of 220,000 and 300,000. These bands contain trkA, but were not immunoprecipitated by p75NGFR-specific antisera, suggesting that they do not represent trkA/p75NGFR protein complexes. The 220-kDa trkA band apparently represents trkA with alternate post-translational modification. The appearance of the 300-kDa trkA band was dependent on cross-linker concentration and could be diminished in the presence of reducing agents, suggesting that it represents a trkA dimer. All trkA bands were phosphorylated on tyrosine residues when bound to mNGF, suggesting that they participate in NGF-induced signal transduction. NGF binding kinetics to all three trkA bands were indistinguishable, with slow dissociation rates, and a slow association rate that required approximately 1 h to reach equilibrium levels at 4 degrees C. All three trkA bands bound the related neurotrophin brain-derived neurotrophic factor and neurotrophin-3 with a profile characteristic of trkA.

Mechanism of impaired energy metabolism during acidosis: role of oxidative metabolism

Isolated perfused rat hearts were used to study the effects of metabolic acidosis on energy metabolism. Hearts perfused with different substrates (glucose, pyruvate, and succinate) were subjected to metabolic acidosis. With all substrates, there were comparable decrements in oxygen consumption (approximately 35%), cardiac function (decrease in first derivative of pressure of 65%), and similar changes in high-energy phosphates (approximately 150% increases in inorganic phosphate and 25% decreases in phosphocreatine concentrations) with metabolic acidosis. To further investigate the metabolic effects of acidosis, isolated cardiac mitochondria were exposed to different incubation media pH conditions and given simple metabolites (glutamate/malate, succinate, or pyruvate) or fatty acids (octanoate). Reduction of incubation media pH to 6.0 did not significantly affect either coupled respiration rate or the respiratory control ratio (RCR) with any substrate. These data suggest that metabolic acidosis induces decreases in energy production in the isolated perfused heart by inhibiting mitochondrial substrate utilization and not by impairing glycolysis. However, this impairment of mitochondrial function is not a direct effect of acidosis itself but appears to occur secondarily to some other effects of acidosis which are, as yet, incompletely understood.

Prostate Cancer: New serum tumor marker for monitoring patients

As the incidence of prostatic cancer rises, family physicians can expect to diagnose and treat increasing numbers of patients with this disease. Recent research has uncovered a new serum tumor marker (prostate-specific antigen), which is useful in patient monitoring and which eventually could be used in screening. A current review of available serum tumor markers is presented.

Agreement between clinical methods of measurement of urinary frequency and functional bladder capacity

We assessed the agreement between 2 methods of data gathering of particular interest in urology: patient questionnaire and examination vs. frequency-volume charts. One hundred consecutive patients consulting our out-patient clinic were chosen for this study; 88 completed the study. Urinary frequency and bladder capacity were evaluated in each patient by using the above methods. The agreement between different methods of measurement was assessed by determining whether the 2 methods were interchangeable, a condition occurring if results of both methods fall within predetermined limits of variability. The results showed poor agreement between subjectively estimated urinary frequency and chart-determined urinary frequency. Moreover, different methods of measuring bladder capacity (endoscopic vs. chart) gave different results. Since chart-determined data are probably a more valid indication of urinary habits, we suggest that frequency-volume charts should be used more often in the investigation and follow-up of patients with micturition disorders.

The integrated academic information management system at Columbia-Presbyterian Medical Center

Over the past seven years, Columbia-Presbyterian Medical Center has been planning and implementing an integrated academic information management system. Accomplishments to date include establishing an institutional information architecture, installing a campus-wide network of workstations, recruiting the staff needed to develop and implement the system, and developing various applications. This paper presents the rationale and steps involved in these accomplishments, as well as data on use of the system so far.

The urine specific gravity dipstick: a useful tool to increase fluid intake in stone forming patients

High fluid intake is the only preventive dietary measure that can be recommended to all patients with stones. However, the efficacy of dietary advice given to patients is unknown. We compared the impact of dietary advice to increase hydration (group 1, 57 patients) and of no dietary advice (group 2, 83 patients) on 24-hour urine volume. No significant difference was noted between groups 1 (1,624 ml.) and 2 (1,732 ml.). We then determined if urine specific gravity dipsticks could help patients increase the 24-hour urine volume. A correlation between 24-hour urine volume and mean urine specific gravity was performed on 263 randomly chosen patients. There was an inverse relationship between urine specific gravity and 24-hour urine volume with a correlation coefficient of 0.522 (y = 1.0207 - 0.00374x). Most patients (81.6%) with 24-hour urine volumes of less than 2.1 had a urine specific gravity of more than 1.010. The use of specific gravity dipsticks was evaluated as a tool to help 24 patients increase the 24-hour urine volume. The 24-hour urine volume increased significantly (p less than 0.05, paired Student's t test) in patients after feedback from specific gravity dipsticks when they were instructed to keep the urine specific gravity at or less than 1.010 (average 24-hour urine volume increased 192%). We conclude that dietary advice may be insufficient to modify fluid intake habits in stone patients. However, modifications of fluid intake habits may be improved by feedback from specific gravity dipsticks.

An initial assessment of the cost and utilization of the Integrated Academic Information System (IAIMS) at Columbia Presbyterian Medical Center

The concept of "one stop information shopping" is becoming a reality at Columbia Presbyterian Medical Center (CPMC). The goal of our effort is to provide access to university and hospital administrative systems as well as clinical and library applications from a single workstation, which also provides utility functions such as word processing and mail. Since June 1987, CPMC has invested the equivalent of $23 million dollars to install a digital communications network that encompasses 18 buildings at seven geographically separate sites and to develop clinical and library applications that are integrated with the existing hospital and university administrative and research computing facilities. During June 1991, 2425 different individuals used the clinical information system, 425 different individuals used the library applications, and 900 different individuals used the hospital administrative applications via network access. If we were to freeze the system in its current state, amortize the development and network installation costs, and add projected maintenance costs for the clinical and library applications, our integrated information system would cost $2.8 million on an annual basis. This cost is 0.3% of the medical center's annual budget. These expenditures could be justified by very small improvements in time savings for personnel and/or decreased length of hospital stay and/or more efficient use of resources. In addition to the direct benefits which we detail, a major benefit is the ease with which additional computer-based applications can be added incrementally at an extremely modest cost.

Chronic anaemia, hyperbaric oxygen and tumour radiosensitivity

Anaemia is an important factor in the response of some human tumours to radiotherapy. The outcome is also influenced by whether the treatment is given in air or high pressure oxygen (HPO). The present study examined the relationship between anaemia and tumour response to radiation given in air or HPO in C3H mice transplanted with a mammary adenocarcinoma using a growth delay assay to assess the radiation response. Chronic anaemia was induced by the use of a low iron diet and was characterized by a significant reduction in host haematocrit and whole blood viscosity. In addition, anaemia was associated with a right shift in the oxyhaemoglobin dissociation curve and an increase in the volume doubling time of the tumour; but there was no change in the concentration of 2,3-diphosphoglycerate in the red cells. Radiation studies with these anaemic mice demonstrated that the tumour radiosensitivity was decreased when treatment was given in air. HPO was successful in overcoming the increased radioresistance associated with anaemia. This result suggested that tumours grown in anaemic mice have a higher hypoxic fraction than those grown in control mice. Changes in host physiology with chronic anaemia may contribute to the benefit seen with HPO but such alterations per se may be inadequate to maintain tumour oxygenation when treatment is given in air.

Physiologic consequences and complications of vasectomy

Sterilization of men and women is the most popular method of contraception in Canada. The contraceptive effect of a vasectomy usually occurs within 3 months. The production of sperm, however, is not interrupted, and an increase in pressure proximal to the ligation site may cause rupture of the epididymis or the ductus deferens, with extravasation of spermatozoa and the formation of granulomas or sperm antibodies. Increased pressure may also explain the postvasectomy pain syndrome.

Effect of liver fatty acid binding protein on fatty acid movement between liposomes and rat liver microsomes

Although movement of fatty acids between bilayers can occur spontaneously, it has been postulated that intracellular movement is facilitated by a class of proteins named fatty acid binding proteins (FABP). In this study we have incorporated long chain fatty acids into multilamellar liposomes made of phosphatidylcholine, incubated them with rat liver microsomes containing an active acyl-CoA synthetase, and measured formation of acyl-CoA in the absence or presence of FABP purified from rat liver. FABP increased about 2-fold the accumulation of acyl-CoA when liposomes were the fatty acid donor. Using fatty acid incorporated into liposomes made either of egg yolk lecithin or of dipalmitoylphosphatidylcholine, it was found that the temperature dependence of acyl-CoA accumulation in the presence of FABP correlated with both the physical state of phospholipid molecules in the liposomes and the binding of fatty acid to FABP, suggesting that fatty acid must first desorb from the liposomes before FABP can have an effect. An FABP-fatty acid complex incubated with microsomes, in the absence of liposomes, resulted in greater acyl-CoA formation than when liposomes were present, suggesting that desorption of fatty acid from the membrane is rate-limiting in the accumulation of acyl-CoA by this system. Finally, an equilibrium dialysis cell separating liposomes from microsomes on opposite sides of a Nuclepore filter was used to show that liver FABP was required for the movement and activation of fatty acid between the compartments. These studies show that liver FABP interacts with fatty acid that desorbs from phospholipid bilayers, and promotes movement to a membrane-bound enzyme, suggesting that FABP may act intracellularly by increasing net desorption of fatty acid from cell membranes.

SV40 small t antigen enhances the transformation activity of limiting concentrations of SV40 large T antigen

A murine recombinant Neo(r) retrovirus encoding the SV40 small t antigen was used to infect Balb/c 3T3 CIA31 cells. From analyses of G418-resistant clones containing at least as much intact t as Cos-1 cells, we found that t, alone, had no detectable A31 transforming activity. In contrast, we noted that SV40 large T promoted A31 agar colony formation when present over a 5- to 7.5-fold concentration range. However, at the low end of the spectrum, its transforming effect was manifest inefficiently except in the presence of t. Thus a major role for t in the SV40 transforming mechanism is to enhance directly or indirectly the transforming function of T.

A recombinant murine retrovirus for simian virus 40 large T cDNA transforms mouse fibroblasts to anchorage-independent growth

A recombinant murine retrovirus containing the intact cDNA sequence for the simian virus 40 (SV40) large T antigen (T) was constructed by using the pZIPNeo SV(X)1 vector. Psi 2 packaging cells were then transfected, and G418-resistant clones were used to generate helper-free viral stocks. NIH 3T3 mouse fibroblasts infected by the recombinant T cDNA retrovirus were selected fro G418 resistance. Such cultures synthesized authentic SV40 T and were transformed to anchorage-independent growth at high efficiency. Therefore, this vector has allowed the study of the transformation properties of T under conditions of neutral drug selection and in the absence of SV40 small t antigen.

Antenatal diagnosis of sickle cell disease: amniotic fluid cell DNA analysis

Using recombinant DNA methods and amniocentesis, the antenatal diagnosis of sickle cell disorders can be accomplished. This article presents the authors' experiences with 21 pregnancies at risk using HpaI and Hind III restriction enzyme digestions of adult leukocytic and fetal amniotic fluid cell DNA. The authors were able to establish direct beta A- and beta S-globin gene linkages to the restricted fragments in 9 families. In 8 families no direct linkages could be determined and estimates of exclusion of fetal beta S homozygosity were used. These estimates were made on the basis of the frequencies of association of the HpaI fragments with the beta S and beta A genes in the Afro-American population. In 4 families, no estimates or linkages could be established, and the patients were counseled in reference to fetoscopy. The data also indicated the frequencies of association of the HpaI fragments with the beta A and beta S gene in the New Jersey-New York population. These studies did not seem to indicate any exclusive preferential segregation of the HpaI and Hind III polymorphisms.

Solid-phase radioimmunoassay of cell specific chromosomal proteins

A solid-phase radioimmunoassay has been developed for the detection of cell specific chromosomal proteins which require the presence of DNA for their immunoreactivity. The assay involves the binding of chromatin particles sonicated under highly controlled conditions to PVC plates followed by first and second antibody with extensive detergent washing. The sensitivity and specificity of the assay system compares favourably with the complement fixation technique.

Impairments in limb actions after dorsal funiculi section in cats

A study of the forces exerted by cats against the ground when jumping from a platform equipped with force transducers, was carried out. The study, complemented by film analysis of the jump, attempted to disclose some of the mechanisms underlying the decrease in efficiency and accuracy in releasing a moving piece of liver observed after dorsal funiculi section above C1 level. The results showed that after the lesion, peak force and height of jump were significantly reduced. However, angle of take-off, an index of force distribution in the three axes of rectangular coordinates remained unchanged. Intact cats consistently extend their forelimbs in a smooth and progressive way toward the liver in order to release it. The distance between the tips of the forelimbs remained more or less constant during the flight. Postoperatively, instead of the regular pattern described, the extension of the limbs was interrupted by fast marked flexion movements and the distance between their tips increased significantly during the flight. Peak extension of the forelimbs was also decreased after surgery. The results are interpreted in terms of the different disruption of the various components (proprio and exteroceptive) that make up fasciculus gracilis and cuneatus of the dorsal funiculi.

A hypothesis for the increased oxygen affinity in haemoglobin Malmö

Haemoglobin Malmöbeta97His leads to Gln, a high oxygen affinity haemoglobin which causes secondary erythrocytosis, is transmitted in an autosomal dominant manner. A hypothesis accounting for the high oxygen affinity, hyperbolic oxyhaemoglobin dissociation curve, and the relatively normal Bohr effect is presented. The purified abnormal haemoglobin from the present family provided biochemical and functional data for this hypothesis based on the allosteric model proposed by Perutz. Experimental results support the formation of a chemical bond between the -SH proton of the beta93 cysteine and the amide of oxygen of the substituted beta97 glutamine as an explanation for the high oxygen affinity of haemoglobin Malmö.