Relapsing and remitting severe hypoglycemia due to a monoclonal anti-insulin antibody heralding a case of multiple myeloma

CONTEXT

We report a novel case of insulin autoimmune syndrome (IAS) presenting with hypoglycemia due to production of a monoclonal anti-insulin antibody in a patient subsequently found to have multiple myeloma (MM).

OBJECTIVE

The aim of the study was to describe the 5-yr clinical course of a patient with IAS and MM and to characterize the origin and function of the pathogenic antibody.

METHODS

We conducted a longitudinal case history with laboratory investigations to characterize the anti-insulin antibody subtype, specificity, affinity, and origin.

RESULTS

The patient presented with IAS, which worsened during treatment of hepatitis C. The patient was then discovered to have a monoclonal gammopathy that progressed to MM. Treatment of the MM induced remission of the neoplasia and IAS, which then followed a synchronized course of progression and response to therapy. An anti-insulin IgG(3)-λ that bound specifically but with low affinity to the insulin B chain (amino acids 9-30) and that was distinct from the primary MM IgG(3)-κ clone was recovered from the patient and cloned. The antibody bound insulin and showed mutations of normal affinity maturation.

CONCLUSIONS

We describe a case of MM heralded by IAS, where full characterization of the pathogenic antibody revealed that the monoclonal anti-insulin antibody had originated from a self-reactive clone.

Effect of vitamin A content in cafeteria diet on the expression of nuclear receptors in rat subcutaneous adipose tissue

The aim of this study was to determine the effects of cafeteria diet containing control or elevated level of vitamin A on the expression of nuclear receptors in adipose tissue. Male Wistar rats were submitted to 3 experimental diets during 8 weeks, a standard diet and two hyper-energetic, hyperlipidic "cafeteria" diets containing normal (Caf) or higher (Caf+) vitamin A level. During the experiment, body weights and energy intakes were measured. At the end of the experimental period, subcutaneous adipose tissue (Swat) and all the fat mass were removed and weighted. Nuclear receptors mRNA levels of RARalpha, RARgamma, RXRalpha, PPARgamma were measured in the Swat by a real-time semi-quantitative RT-PCR method. We observed that energy intake of Caf+ and Caf groups was significantly higher than that of the control group. Despite a higher increase of the energy intake in the Caf group compared to the Caf+ group, no significant difference was observed in the body weight gain of the Caf+ compared to the Caf group. The Caf+ and Caf diets led to a significant increase of adipose tissue in cafeteria groups as observed in the Swat depot. The mRNA levels of PPARgamma and RXRalpha were significantly increased in the Caf+ group as compared to control group, with a significant positive correlation between these two parameters. Expressions of RARalpha and RARgamma were not modified in experimental groups compared to controls. In conclusion, 8-week exposure to cafeteria diets with normal and higher levels of vitamin A led to an increase of adiposity in rats, associated, only in the group fed with the higher vitamin A level cafeteria diet, with an increase of PPARgamma and RXRalpha expressions in subcutaneous adipose tissue.

[Lisch nodules: description of 2 clinical cases and their significance]

We report two cases of Lisch nodules in both eyes in two women. It was the only ocular manifestation of their Von Recklinghausen disease. The other general signs of their disease were cutaneous neurofibromas. Lisch nodules are melanocytic hamartomas consisting of melanocytic cells containing various quantities of pigment. They can be found in 90 to 100% of neurofibromatosis patients over 6 years of age. They are practically pathognomonic of type 1 neurofibromatosis and their finding is an important diagnostic argument. They must be distinguished from other iris nodules: nevus, melanoma, inflammatory nodules, and development anomalies.

Prevalence of sexual abuse history in a sample of women seeking treatment for premenstrual syndrome

This study evaluated the prevalence and correlates of sexual abuse history among women seeking treatment for severe premenstrual syndrome (PMS). Of 77 women participating in a randomized clinical trial of non-pharmacological treatments for severe PMS, 42 were interviewed regarding their sexual abuse history. The interviewed women were a mean of 38 years old, and most were of European ancestry, heterosexual, married, employed and well-educated. At least one attempted or completed sexual abuse event was reported by 95% of the women, with 81% reporting completed penetration against their will and 85% of these sustaining physical threat or harm. Compared to prior studies of sexually abused women in general populations, these women were abused earlier in life, more frequently and by similar types of offenders. Most of the abused women (65%) were estimated to have post-traumatic stress disorder (PTSD). Most abused women (83%) had never disclosed the abuse to a health practitioner. The findings suggest that a history of sexual abuse, particularly in childhood or adolescence, may be extremely common among women seeking treatment for severe PMS, and that substantial undiagnosed PTSD may also be present in this population. Implications for patient screening and treatment are discussed.

Cross-desensitization of receptors for peptide chemoattractants. Characterization of a new form of leukocyte regulation

The formylpeptide (fMLP) and C5a chemoattractants were previously shown to cross-desensitize each other's ability to mobilize Ca2+ in leukocytes but not to affect nonchemoattractant Ca(2+)-mobilizing receptors, and vice versa. Our data show that all receptors studied underwent homologous desensitization. Interestingly, peptide chemoattractants (fMLP, C5a, and IL-8) desensitized each other's Ca(2+)-mobilizing responses, but had no effect on a Ca(2+)-mobilizing purinergic receptor. Lipid chemoattractant receptors (PAF and leukotriene B4) were also desensitized by peptide chemoattractants but not vice versa. In the presence of cytochalasin B, only fMLP and C5a caused the activation of phospholipase D in intact leukocytes and enhanced desensitization of IL-8 and C5a but not fMLP receptors. To measure receptor/G protein interactions, agonist-stimulated GTP gamma S binding to leukocyte membranes was measured. Whereas all peptide receptors underwent homologous desensitization, C5a and IL-8, but not fMLP, receptors were cross-desensitized by other peptide chemoattractants. Furthermore, PMA caused inhibition of C5a- and IL-8- but not fMLP-stimulated GTP gamma S binding. These data suggest that in addition to homologous desensitization, peptide chemoattractant receptors cross-desensitize one another by at least two processes. One can be detected at the level of receptor/G-protein interaction and possibly involves receptor phosphorylation by protein kinase C. The fMLP receptor is resistant to this process. The second process is distal to receptor/G-protein interaction and utilizes an undefined pathway to cross-desensitize the Ca2+ mobilization response to all peptide chemoattractants. We propose that receptor cross-desensitization in leukocytes is orchestrated at several levels by mechanisms with selectivity for types of chemoattractant receptors.

Cross-desensitization of receptors for peptide chemoattractants. Characterization of a new form of leukocyte regulation

The formylpeptide (fMLP) and C5a chemoattractants were previously shown to cross-desensitize each other's ability to mobilize Ca2+ in leukocytes but not to affect nonchemoattractant Ca(2+)-mobilizing receptors, and vice versa. Our data show that all receptors studied underwent homologous desensitization. Interestingly, peptide chemoattractants (fMLP, C5a, and IL-8) desensitized each other's Ca(2+)-mobilizing responses, but had no effect on a Ca(2+)-mobilizing purinergic receptor. Lipid chemoattractant receptors (PAF and leukotriene B4) were also desensitized by peptide chemoattractants but not vice versa. In the presence of cytochalasin B, only fMLP and C5a caused the activation of phospholipase D in intact leukocytes and enhanced desensitization of IL-8 and C5a but not fMLP receptors. To measure receptor/G protein interactions, agonist-stimulated GTP gamma S binding to leukocyte membranes was measured. Whereas all peptide receptors underwent homologous desensitization, C5a and IL-8, but not fMLP, receptors were cross-desensitized by other peptide chemoattractants. Furthermore, PMA caused inhibition of C5a- and IL-8- but not fMLP-stimulated GTP gamma S binding. These data suggest that in addition to homologous desensitization, peptide chemoattractant receptors cross-desensitize one another by at least two processes. One can be detected at the level of receptor/G-protein interaction and possibly involves receptor phosphorylation by protein kinase C. The fMLP receptor is resistant to this process. The second process is distal to receptor/G-protein interaction and utilizes an undefined pathway to cross-desensitize the Ca2+ mobilization response to all peptide chemoattractants. We propose that receptor cross-desensitization in leukocytes is orchestrated at several levels by mechanisms with selectivity for types of chemoattractant receptors.

Purification and characterization of an ADP-ribosyltransferase produced by Clostridium limosum

We purified a novel ADP-ribosyltransferase produced by a Clostridium limosum strain isolated from a lung abscess and compared the exoenzyme with Clostridium botulinum ADP-ribosyltransferase C3. The C. limosum exoenzyme has a molecular weight of about 25,000 and a pI of 10.3. The specific activity of the ADP-ribosyltransferase is 3.1 nmol/mg/min with a Km for NAD of 0.3 microM. Partial amino acid sequence analysis of the tryptic peptides revealed about 70% homology with C3. The novel exoenzyme modifies selectively the small GTP-binding proteins of the rho family in human platelet membranes presumably at the same amino acid (asparagine 41) as known for C3. Recombinant rhoA and rhoB serve as substrates for C3 and the C. limosum exoenzyme. Whereas recombinant rac1 protein is only marginally ADP-ribosylated by C3 or by the C. limosum exoenzyme in the absence of detergent, in the presence of 0.01% sodium dodecyl sulfate rac1 is modified by C3 but not by the C. limosum exoenzyme. Recombinant CDC42Hs protein is a poor substrate for C. limosum exoenzyme and is even less modified by C3. The C. limosum exoenzyme is auto-ADP-ribosylated in the presence of 0.01% sodium dodecyl sulfate by forming an ADP-ribose protein bond highly stable toward hydroxylamine. The data indicate that ADP-ribosylation of small GTP-binding proteins of the rho family is not unique to C. botulinum C3 ADP-ribosyltransferase but is also catalyzed by a C3-related exoenzyme from C. limosum.

An affinity matrix for the purification of poly(ADP-ribose) glycohydrolase

The preparation of quantities of poly(ADP-ribose) glycohydrolase sufficient for detailed structural and enzymatic characterizations has been difficult due to the very low tissue content of the enzyme and its lability in late stages of purification. To date, the only purification of this enzyme to apparent homogeneity has involved a procedure requiring 6 column chromatographic steps. Described here is the preparation of an affinity matrix which consists of ADP-ribose polymers bound to dihydroxyboronyl sepharose. An application is described for the purification of poly(ADP-ribose) glycohydrolase from calf thymus in which a single rapid affinity step was used to replace 3 column chromatographic steps yielding enzyme of greater than 90% purity with a 3 fold increase in yield. This matrix should also prove useful for other studies of ADP-ribose polymer metabolism and related clinical conditions.

Effect of hyperthermia on poly(adenosine diphosphate-ribose) glycohydrolase

The effects of supranormal temperature on the activity of poly(ADP-ribose) glycohydrolase were studied by assaying the enzyme in cell extracts derived from cells subjected to hyperthermia and comparing with extracts that were heated in vitro. The enzyme activity was reduced by both hyperthermic treatment of cells and by heating of cell extracts; however greater reductions were observed when intact cells were subjected to hyperthermia. The additional reduction observed when intact cells were heated was reversed when cells were allowed to recover at 37 degrees C following hyperthermia. We postulate that hyperthermia alters poly(ADP-ribose) glycohydrolase activity by two mechanisms, an irreversible thermal denaturation of the enzyme and a reversible metabolic alteration. Changes in poly(ADP-ribose) glycohydrolase activity can account in full for the observed alterations of poly(ADP-ribose) metabolism that occur following hyperthermia.

A possible case of osteodystrophia fibrosa cystica in a horse

A case of unilateral front leg lameness with bone changes in the pedal bone suggestive of osteodystrophia fibrosa cystica is reported in an eight year old crossbred gelding. The changes were diagnosed at postmortem examination. The known possible causes are briefly reviewed.