A case of xanthoma disseminatum: evaluation and monitoring by 18F-fluorodeoxyglucose positron emission tomography/computed tomography

Xanthoma disseminatum (XD) is a rare benign histiocytic disorder with extensive mucocutaneous xanthomas that often involves other sites such as the central nervous system (CNS), respiratory tract and abdominal organs. Evaluation of the extent of disease is important because lesions in critical locations may increase morbidity and mortality. However, there are no well-established tools for the evaluation and monitoring of XD. Here, we report a case of XD in a 21-year-old male patient showing skin, mucous membrane, CNS and internal organ involvement. In this case, (18) F-fluorodeoxyglucose positron emission tomography/computed tomography was useful in detecting the extent of the disease and in estimating the therapeutic response.

PEGylation improves the hypoglycaemic efficacy of intranasally administered glucagon-like peptide-1 in type 2 diabetic db/db mice

AIMS

PEGylation - covalent modification of therapeutic peptides with polyethylene glycol (PEG) - is viewed as an effective way of prolonging the short lifetime of glucagon-like peptide-1 (GLP-1). In this study, we investigated the hypoglycaemic efficacies of PEGylated GLP-1s administered intranasally in type 2 diabetic db/db mice.

METHODS

Three types of site-specific (Lys(34)) PEGylated GLP-1 analogues (PEG molecular weight: 1, 2 or 5 kDa) were synthesized. Their metabolic stabilities were evaluated in nasal mucosa enzyme pools. Oral glucose tolerance test was conducted 30, 60 and 120 min after intranasally administering these analogues in type 2 diabetic db/db mice.

RESULTS

PEGylated GLP-1 analogues were found to have significantly longer half-lives than native GLP-1 in nasal mucosa enzymes (2.4-fold to 11.0-fold, p < 0.005). Non-PEGylated GLP-1 at 100 nmol/kg was not found to have marked efficacy irrespective of nasal administration time [total hypoglycaemic degree (HD(total)) values 2.8-17.3%]. On the contrary, PEGylated GLP-1s (100 nmol/kg) showed obvious efficacies with maximum HD(total) values of >51.8 +/- 5.8% (p < 0.005 vs. GLP-1).

CONCLUSION

This study highlights the pharmacological potential of intranasally administered PEGylated GLP-1s in terms of stabilizing postprandial hyperglycaemia in type 2 diabetic patients.

Bioactive polymers for biohybrid artificial pancreas

To address the solution for some of the obstacles, such as low insulin secretion, limited lifespan and aggregation of transplanted islets, encountered in developing a biohybrid artificial pancreas (BAP), polymeric materials including a reversible polymeric extracellular matrix (ECM), crystallized glucagon-like peptide-1, and oxygen carrying polymers, were prepared and their potential utilities in designing a compact and rechargeable BAP were investigated. For a synthetic, reversible ECM, high molecular weight N-isopropylacrylamide copolymer with a small amount of acrylic acid (2 mole%) was synthesized by conventional radical polymerization in benzene, and its aqueous solution above a critical polymer concentration displayed a sol-gel transition temperature near physiological temperature (33-35 degrees C) without noticeable hysteresis. The physicochemical properties of the gel with islet compatibility proved that the synthetic ECM is an appropriate matrix which can make a BAP rechargeable. Glucagon-like peptide-1 (GLP-1, 7-37) is known to have a strong stimulatory effect on insulin secretion, particularly at high glucose concentrations. When zinc-crystallized GLP-1 was entrapped along with islets in a hollow fiber macrocapsule device, insulin secretion was enhanced at a high glucose concentration (300 mg/dl) with a >85% increase in insulin secretion after an induction period. The cross-linked hemoglobin with difunctional PEO (Hb-C) was prepared to increase the high molecular weight of Hb. This prevents diffusional loss when enclosed in an immunoprotecting membrane. The Hb-C, entrapped in microcapsules, enhanced insulin secretion and improved the viability of microencapsulated islets by promoting oxygen supply to islets. The introduction of the synthetic ECM, crystallized GLP-1, and Hb-C into a BAP may provide a basis for designing a compact and rechargeable BAP (macrocapsule).

Synthesis of sulfonylurea conjugated copolymer via PEO spacer and its in vitro short-term bioactivity in insulin secretion from islets of Langerhans

In order to reduce the number of immunoprotected islets required in xeno- or allogenic transplants for reversing diabetes, analogues of glyburide (a sulfonylurea), an extremely hydrophobic insulin secretagogue, were synthesized and used in an attempt to produce water soluble sulfonylurea (SU) grafted polymers. After synthesizing various polymers containing glyburide analogues, a poly(N-vinyl-2-pyrrolidone-co-sulfonylurea succinyl PEO (Mw = 3000) acrylate) was found to be soluble in a cell culture medium at pH 7.4. However, solubility was only obtained by decreasing solution pH from 11 to 7.4. When the copolymer was added to the islet cell culture media at a concentration of 5 microg ml(-1) (based on the theoretical SU content of the copolymer), insulin secretion was enhanced by about 30% at low glucose concentrations of 50 and 100 mg dl(-1) compared to the control. This is equivalent to 40-60% bioactivity of glyburide. The polymer's effect on insulin secretion at a higher glucose concentration of 200 mg dl(-1) was not significant. Considering the previous results where a similar but insoluble polymer without a PEO spacer was used and the polymer showed SU bioactivity only at a glucose concentration of 50 mg dl(-1), the observations from this study indicates that the solubility of SU-grafted polymers may affect the binding of SU groups to SU receptors on the pancreatic beta-cells, resulting in improved pharmacodynamic effect of SU.

Vestibulo-ocular reflex in eccentric rotation in squirrel monkeys

In addition to angular acceleration, eccentric rotation (ECR) imparts linear acceleration to the head positioned eccentric to the axis of rotation. Using ECR in squirrel monkeys, the effects of otolith organ stimulation by linear acceleration on vestibulo-ocular reflex (VOR) gain were investigated. With the animal's head facing away from the rotation axis, ECR significantly enhanced VOR gain over that seen in centric rotation (CR) at 1.0 Hz, but not at 0.5 Hz. However, no enhancement of VOR gain at 1.0 Hz was observed in eccentriclateral rotation when the animal faced tangentially. After bilateral ablation of the otolith organs (sacculectomy and utricular neurectomy), the ECR did not increase VOR gain, even at 1.0 Hz. In animals in which the lateral and posterior semicircular canals were plugged bilaterally, horizontal sinusoidal eye movements were induced by ECR at 1.0 Hz; no clear compensatory eye movement occurred during CR at 1.0 Hz. These findings demonstrate that during ECR, tangential acceleration along the interaural axis stimulates the utricular maculae, inducing horizontal eye movements in addition to those induced by the semicircular canal, thus resulting in an enhancement of VOR gain. Our results also suggest synergistic interactions of the otolith organs and semicircular canals. We conclude that ECR is a useful clinical test of the function of the otolith organs.

Effects of otolith stimulation in eccentric rotation on the vestibulo-ocular reflex in squirrel monkeys

When a subject is rotated around an axis located behind his head (eccentric rotation, ECR), he experiences a combination of angular acceleration and two kinds of linear accelerations, tangential and centrifugal. The effects of stimulation of the otolith organs by linear acceleration in ECR on gain of the vestibulo-ocular reflex (VOR) were examined in squirrel monkeys. The VOR gain in ECR with the animal's head facing away from the rotation axis was significantly higher than that in centric rotation (CR) at 1.0 Hz, but not at 0.5 Hz. However, the VOR gain did not increase in eccentric-lateral rotation when the animal faced tangentially, even at 1.0 Hz. After bilateral ablation of the otolith organs (sacculectomy and utricular neurectomy), the VOR gain in ECR did not increase, even at 1.0 Hz. These findings demonstrate that tangential acceleration along the interaural axis in ECR stimulates the utricular maculae, resulting in enhancement of the VOR gain. The results also suggest that ECR is a useful clinical test for the function of the otolith organs.

Recovery of the otolith-ocular reflex after unilateral deafferentation of the otolith organs in squirrel monkeys

The enhancement of the vestibulo-ocular reflex (VOR) gain in the eccentric rotation is mediated by the otolith organs. Functional recovery of the otolith-ocular reflex after deafferentation of the otolith organs was examined in squirrel monkeys, using the enhancement of the eccentric VOR gain as an indicator of the reflex. After unilateral deafferentation of the otolith organs, the enhancement of the eccentric VOR gain decreased and then recovered completely within eight weeks. However, the eccentric VOR gain was not enhanced after contralateral side lesions. These findings demonstrate that functional recovery of the otolith-ocular reflex is achieved after unilateral deafferentation of the otolith organs, and that afferents from the remaining otolith organs are necessary for the functional compensation.

Sodium concentration in saliva along the time course of experimental Coriolis sickness

Procedures designed to evaluate the severity of motion sickness have included subjective reporting of changes in salivation. In order to increase objectivity, we studied the sodium concentration of saliva, which is directly related to the flow rate. Healthy adults with normal vestibular function underwent a modified Coriolis Sickness Susceptibility Index (CSSI) test, utilizing a staircase profile. Saliva was collected without interrupting the stimulus by means of cotton placed beneath the subject's tongue for one minute. Samples were obtained 5 min prior to stimulation, 30 and 45 min following stimulus onset, and/or upon reaching the "nausea II" endpoint. Saliva for analysis by atomic absorption spectrophotometry was obtained by centrifugation of the cotton. A significant difference in sodium concentration was found between the baseline and 30-min sample (p less than 0.01). Although the amount of salivation was rather variable, the pattern of changes in sodium concentration was similar in all experimental cases.