Antibodies to cannabinoid type 1 receptor co‐react with stomatin‐like protein 2 in mouse brain mitochondria

Anti‐cannabinoid type 1 receptor (CB₁) polyclonal antibodies are widely used to detect the presence of CB₁ in a variety of brain cells and their organelles, including neuronal mitochondria. Surprisingly, we found that anti‐CB₁ sera, in parallel with CB₁, also recognize the mitochondrial protein stomatin‐like protein 2. In addition, we show that the previously reported effect of synthetic cannabinoid WIN 55,212‐2 on mitochondrial complex III respiration is not detectable in purified mitochondrial preparations. Thus, our study indicates that a direct relationship between endocannabinoid signaling and mitochondrial functions in the cerebral cortex seems unlikely, and that caution should be taken interpreting findings obtained using anti‐CB₁ antibodies.     

Targeted deletion of histidine decarboxylase gene in mice increases bone formation and protects against ovariectomy-induced bone loss

Targeted disruption of the histidine decarboxylase gene (HDC(-/-)), the only histamine-synthesizing enzyme, led to a histamine-deficient mice characterized by undetectable tissue histamine levels, impaired gastric acid secretion, impaired passive cutaneous anaphylaxis, and decreased mast cell degranulation. We used this model to study the role of histamine in bone physiology. Compared with WT mice, HDC(-/-) mice receiving a histamine-free diet had increased bone mineral density, increased cortical bone thickness, higher rate of bone formation, and a marked decrease in osteoclasts. After ovariectomy, cortical and trabecular bone loss was reduced by 50% in HDC(-/-) mice compared with WT. Histamine deficiency protected the skeleton from osteoporosis directly, by inhibiting osteoclastogenesis, and indirectly, by increasing calcitriol synthesis. Quantitative RT-PCR showed elevated 25-hydroxyvitamin D-1alpha-hydroxylase and markedly decreased 25-hydroxyvitamin D-24-hydroxylase mRNA levels. Serum parameters confirming this indirect effect included elevated calcitriol, phosphorus, alkaline phosphatase, and receptor activator of NF-kappaB ligand concentrations, and suppressed parathyroid hormone concentrations in HDC(-/-) mice compared with WT mice. After ovariectomy, histamine-deficient mice were protected from bone loss by the combination of increased bone formation and reduced bone resorption.     

Effect of catheter diameter on resting pressures in anal fissure patients

PURPOSE: Controversy exists as to whether fissure patients have elevated resting pressures when compared with control patients. The diameter of manometry catheters used in past studies varies widely (1.5–25 mm) and may have contributed to differences observed in resting pressures. A prospective study was undertaken to determine the influence of manometry catheter diameter on maximum resting pressure in patients with idiopathic chronic anal fissures. METHODS: A total of 28 fissure patients and 28 control patients had manometry performed with both a 1.8-mm and a 4.8-mm (external diameter) water-perfused catheter. RESULTS: Mean maximum resting pressure (RP) for fissure patients as measured with the 1.8-mm catheter was 86 (range, 65–115) mmHg and 83 (range, 47–117) mmHg with the 4.8-mm catheter (P=0.65). Mean maximum RP for control patients with the 1.8-mm catheter was 70 (range, 30–108) mmHg and 72 (range, 35–109) mmHg with the 4.8-mm catheter (P=0.07). When fissure and control patients were compared, a significantly higher mean RP was observed in the fissure group for both the 1.8-mm catheter (86 vs.70 mmHg, respectively;P=0.01) and the 4.8-mm catheter (83 vs.72 mmHg, respectively;P=0.03). There was no significant difference in length of the high-pressure zone within each group or when the fissure group and controls were compared, regardless of catheter used. For both groups of patients, there was a significantly higher incidence of ultraslow waves (USWs) observed with the 4.8-mm catheter when compared with the 1.8-mm catheter. The USW frequency was not significantly different when fissure and control groups were compared with either catheter type. CONCLUSIONS: Catheter size did not influence measured maximum RP in fissure patients. The maximum RP was significantly greater for fissure patients overall when compared with the control group, regardless of catheter used. There was an increased frequency of USWs noted with the larger catheter size in all patients; however, these USWs only became apparent when catheter was left at each station until a true baseline RP was obtained.Supported in part by a Columbia-Presbyterian Department of Surgery Research Grant.Poster presentation at the meeting of The American Society of Colon and Rectal Surgeons, Orlando, Florida, May 8 to 13, 1994.     

A case of sparsely granulated growth hormone cell adenoma associated with lymphocytic hypophysitis.

Lymphocytic hypophysitis is in itself rare and usually occurs in the postpartum period or the last trimester of pregnancy. It has not been described in combination with a pituitary tumor. A twenty-two year old woman, who had never been pregnant, presented with a history of nine months amenorrhea and spontaneous galactorrhea. She was not taking any medication and had never used oral contraceptives. Physical examination was unremarkable except that whitish fluid could be expressed from both breasts. Her visual fields were normal. Her serum PRL levels was high at 105.7 micrograms/l and increased to 138.4 micrograms/l at 60 minutes in a triple bolus test. GH values were normal and there was no evidence of overproduction of other pituitary hormones. CT scan showed an intrasellar mass with suprasellar extension. A tumor was selectively removed transsphenoidally. Morphologic examination revealed a clinically silent sparsely granulated growth hormone cell adenoma with lymphocytic infiltration of the adjacent pituitary tissue. Postoperatively her menstrual periods resumed and she conceived despite a slightly elevated PRL level. Three months after an uneventful pregnancy and full term delivery her PRL level was 69.9 micrograms/l and increased to 102.2 micrograms/l at 60 min. Basal GH and cortisol levels were normal. She remains well without replacement fourteen months after delivery. This case is of interest because it is the first reported simultaneous occurrence of a pituitary adenoma and lymphocytic hypophysitis and also because the hypophysitis preceded her first pregnancy.     

Antibodies to glutamic acid decarboxylase and peripheral nerve function in type 1 diabetes

Autoimmune mechanisms have been implicated in the pathophysiology of diabetic neuropathy. We studied the association between glutamic acid decarboxylase (GAD65) and islet cell (IA-2) autoantibodies as well as autoantibodies to the autonomic nervous system and peripheral nerve function in recent onset type 1 diabetes. Thirty-seven patients (27 females and 10 males) enrolled 2-22 months after diagnosis. Humoral factors, glycemic control, and peripheral nerve function were measured annually for 3 yr. Patients with high GAD65Ab had worse glycemic control and higher insulin requirements. Patients with high GAD65Ab had slower motor nerve conduction velocities in the median, ulnar, and peroneal nerves (P < 0.025 for each nerve). The mean motor nerve conduction velocity Z scores at the time of the third evaluation was 0.341 +/- 0.25 for the low GAD65Ab patients and -0.600 +/- 0.25 for the high GAD65Ab patients (P < 0.01). Similar differences between the low and high GAD65Ab groups were observed for F wave latencies, thermal threshold detection, and cardiovascular autonomic function. The composite peripheral nerve function Z scores in the low GAD65Ab patients were 0.62 +/- 11, 0.71 +/- 0.19, and 0.21 +/- 0.14 at the first, second, and third evaluations, significantly different from those in the high GAD65Ab patients in whom they were -0.35 +/- 0.15, -0.46 +/- 0.18, and -0.42 +/- 0.16 (P < 0.001). In summary, GAD65Ab in patients with recent onset type 1 diabetes are associated with worse glycemic control and slightly worse peripheral nerve function. Although the latter remained within normal limits and none of the patients had clinical neuropathy, the GAD65Ab-related differences in composite peripheral nerve function were highly significant (P < 0.001) and could not be attributed to GAD65Ab-related differences in glycemic control.