Adrenal Insufficiency and Thyrotoxicosis Following Combined Immune Checkpoint Inhibitor Use: A Case Report and Literature Review.

Destructive thyroiditis and secondary adrenal insufficiency are major endocrinological immune-related adverse events of immune checkpoint inhibitors (ICIs). However, the timing at which each event occurs most frequently after drug administration varies, and cases where multiple events occur simultaneously are rare. We encountered a patient who concurrently suffered from thyrotoxicosis and adrenal insufficiency. An 80-year-old woman with a history of type 2 diabetes mellitus (DM) was diagnosed with stage IVA squamous cell carcinoma of the lungs. Treatment with a combination of nivolumab and ipilimumab was initiated. Although she tested positive for thyroglobulin antibody and transient subclinical hyperthyroidism was observed after two courses, treatment with ICIs was continued. Four months later, treatment was discontinued due to drug-induced lung disease. One month after the last administration, the patient became unconscious and was admitted to another hospital, diagnosed with diabetic ketoacidosis, urinary tract infection, and sepsis. After acute-phase treatment, she was transferred to our hospital due to persistent fever and tachycardia. Thyrotoxicosis and adrenal insufficiency were observed, with high levels of free thyroxine, low thyroid-stimulating hormone (TSH), and cortisol levels. Treatment with extracellular fluids, potassium iodide, beta-blockers, and hydrocortisone was initiated, and the patient's condition improved. No other pituitary hormone deficiencies were observed. She was diagnosed with painless thyroiditis and secondary adrenal insufficiency based on the positive thyroglobulin antibody, negative TSH receptor antibody, decreased Doppler flow in thyroid ultrasonography, low adrenocorticotrophic hormone (ACTH), and low response of ACTH and cortisol to corticotropin-releasing hormone loading test. MRI revealed no abnormalities. We report a case of thyrotoxicosis and secondary adrenal insufficiency five months after the first administration of nivolumab and ipilimumab. Careful follow-up and early detection of endocrine disorders are critical in patients treated with a combination of ICIs.

Hypopituitarism with secondary adrenocortical insufficiency and arginine vasopressin deficiency due to hypophysitis after COVID-19 vaccination: a case report.

BACKGROUND: Although vaccination against coronavirus disease (COVID-19) has several side effects, hypopituitarism due to hypophysitis has rarely been reported. CASE PRESENTATION: An 83-year-old healthy woman, who had received her fourth COVID-19 vaccine dose 2 days before admission, presented to the emergency department with difficulty moving. On examination, impaired consciousness (Glasgow Coma Scale: 14) and fever were observed. Computed tomography and magnetic resonance imaging of the head revealed swelling from the sella turcica to the suprasellar region. Her morning serum cortisol level was low (4.4 µg/dL) and adrenocorticotropic hormone level was normal (21.6 pg/mL). Central hypothyroidism was also suspected (thyroid stimulating hormone, 0.46 µIU/mL; free triiodothyronine, 1.86 pg/mL; free thyroxine, 0.48 ng/dL). Secondary adrenocortical insufficiency, growth hormone deficiency, delayed gonadotropin response, and elevated prolactin levels were also observed. After administration of prednisolone and levothyroxine, her consciousness recovered. On the 7th day of admission, the patient developed polyuria, and arginine vasopressin deficiency was diagnosed using a hypertonic saline test. On the 15th day, the posterior pituitary gland showed a loss of high signal intensity and the polyuria resolved spontaneously. On the 134th day, the corticotropin-releasing hormone loading test showed a normal response; however, the thyrotropin-releasing hormone stimulation test showed a low response. The patient's disease course was stable with continued thyroid and adrenal corticosteroid supplementation. CONCLUSIONS: Herein, we report a rare case of anterior hypopituitarism and arginine vasopressin deficiency secondary to hypophysitis following COVID-19 vaccination.

[A geriatric case of hyperosmolar hyperglycemic state with osmotic demyelination syndrome that manifested with dysphagia].

The patient was an 84-year-old man who had been on insulin therapy for type 2 diabetes mellitus for 55 years. He had undergone bile duct stenting to avoid obstruction due to adenocarcinoma of the bile duct. The patient had suffered from fever and anorexia for two weeks, and had subsequently stopped insulin therapy. Since he showed signs of impaired consciousness, he was taken to the emergency room, and was diagnosed with a hyperosmotic hyperglycemic state (HHS) based on the following laboratory findings: blood glucose, 632 mg/dL; plasma osmolality, 391 mOsm/kg·H2O; and serum Na, 163 mEq/L, with urine ketone bodies±and sepsis (Klebsiella pneumoniae). He was therefore admitted to the hospital. His blood glucose and serum Na levels slowly improved following the administration of fluids, insulin, and antibiotics. The patient's consciousness disturbance also improved. However, on the third day after admission, dysphagia was newly observed when the patient resumed eating, and swallowing endoscopy revealed a delayed gag reflex and pharyngeal retention of saliva. Cranial magnetic resonance imaging showed a high-intensity area in the central pontine, which was considered to be caused by osmotic demyelination syndrome (ODS). The patient's oral intake ability recovered with swallowing rehabilitation. ODS is a rare complication of HHS. We report a case of HHS with ODS, in which the patient's chief complaint was dysphagia, which should be distinguished from other diseases.

The relationship between blood pressure and cognitive function.

BACKGROUND: Although an elevated systolic blood pressure (SBP) is associated with cognitive dysfunction, BP may decrease with advanced cognitive dysfunction; therefore, we attempted to identify the turning point in the relationship between cognitive function and SBP in elderly subjects. METHODS: In pooled datasets of general populations and outpatient clinics (age>65 years), in which the risk of frailty or cognitive dysfunction was assessed (N = 4076), the relationship between SBP and the Mini Mental State Examination (MMSE) score was examined. RESULTS: Mean age was 72.5 ± 6.2 years (male 45.1%), and SBP was 133.0 ± 19.5 mmHg. In an analysis of locally weighted scatter plot smoothing, the relationship between SBP and MMSE scores changed at an MMSE score of 24 points. In subjects with preserved cognitive function (MMSE ≥24 points), MMSE scores decreased with increases in SBP (B = -0.047 per 10 mmHg increase, P = 0.002) after adjustments for age, sex, body mass index, alcohol habit, smoking status, diabetes, a history of stroke, and the geriatric nutritional index; however, in subjects with reduced cognitive function (MMSE<24 points), decreases in the MMSE score were associated with reductions in SBP (B = 1.178 per 1 point decrease in the MMSE score, P = 0.002). CONCLUSION: The relationship between SBP and cognitive function changed at a MMSE score of approximately 24 points (mild to moderate cognitive dysfunction). In patients with preserved MMSE, higher BP values were associated with a reduction of cognitive function, but this was not a case for those with impaired MMSE.

Primary Aldosteronism Associated with Multiple Adrenocortical Micronodules in a Patient with Renal Cell Carcinoma.

A 47-year-old woman with a history of diabetes mellitus (DM) and obesity was admitted to our hospital for glucose control. She was detected to have hypertension (HT) and diagnosed with primary aldosteronism (PA) based on the high level of aldosterone to renin ratio and the results of the upright furosemide-loading test according to the criteria of the Japanese Society of Hypertension (JSH) guidelines. Computed tomography revealed left renal tumor and adrenocortical adenoma. She underwent left nephrectomy and adrenalectomy. The pathological findings were clear-cell renal cell carcinoma (RCC) and nonfunctional adrenocortical adenoma. Her nonneoplastic adrenal tissue histologically revealed CYP11B2-positive multiple adrenocortical micronodules (MNs) and concomitant paradoxical hyperplasia of the zona glomerulosa. Therefore, MNs were thought to be responsible for PA in this patient. After surgery, HT was improved, and the result of upright furosemide-loading test after 12 months of surgery did not fulfill the criteria of PA according to the JSH guidelines. However, the adrenocorticotrophic hormone stimulation test was positive; considering the possibility of slight aldosterone overproduction from the right adrenal gland, the administration of spironolactone was started. Herein, we report a rare case of RCC in conjunction with PA histologically associated with MNs.

NO donor induces Nec-1-inhibitable, but RIP1-independent, necrotic cell death in pancreatic ß-cells.

Nitric oxide (NO) has been implicated in pancreatic ß-cell death in the development of diabetes. The mechanisms underlying NO-induced ß-cell death have not been clearly defined. Recently, receptor-interacting protein-1 (RIP1)-dependent necrosis, which is inhibited by necrostatin-1, an inhibitor of RIP1, has emerged as a form of regulated necrosis. Here, we show that NO donor-induced ß-cell death was inhibited by necrostatin-1. Unexpectedly, however, RIP1 knockdown neither inhibited cell death nor altered the protective effects of necrostatin-1 in NO donor-treated ß-cells. These results indicate that NO donor induces necrostatin-1-inhibitable necrotic ß-cell death independent of RIP1. Our findings raise the possibility that NO-mediated ß-cell necrosis may be a novel form of signal-regulated necrosis, which play a role in the progression of diabetes.

Inducible nitric-oxide synthase and nitric oxide donor decrease insulin receptor substrate-2 protein expression by promoting proteasome-dependent degradation in pancreatic beta-cells: involvement of glycogen synthase kinase-3beta.

Insulin receptor substrate-2 (IRS-2) plays a critical role in the survival and function of pancreatic ß-cells. Gene disruption of IRS-2 results in failure of the ß-cell compensatory mechanism and diabetes. Nonetheless, the regulation of IRS-2 protein expression in ß-cells remains largely unknown. Inducible nitric-oxide synthase (iNOS), a major mediator of inflammation, has been implicated in ß-cell damage in type 1 and type 2 diabetes. The effects of iNOS on IRS-2 expression have not yet been investigated in ß-cells. Here, we show that iNOS and NO donor decreased IRS-2 protein expression in INS-1/832 insulinoma cells and mouse islets, whereas IRS-2 mRNA levels were not altered. Interleukin-1ß (IL-1ß), alone or in combination with interferon-γ (IFN-γ), reduced IRS-2 protein expression in an iNOS-dependent manner without altering IRS-2 mRNA levels. Proteasome inhibitors, MG132 and lactacystin, blocked the NO donor-induced reduction in IRS-2 protein expression. Treatment with NO donor led to activation of glycogen synthase kinase-3ß (GSK-3ß) and c-Jun N-terminal kinase (JNK/SAPK) in ß-cells. Inhibition of GSK-3ß by pharmacological inhibitors or siRNA-mediated knockdown significantly prevented NO donor-induced reduction in IRS-2 expression in ß-cells. In contrast, a JNK inhibitor, SP600125, did not effectively block reduced IRS-2 expression in NO donor-treated ß-cells. These data indicate that iNOS-derived NO reduces IRS-2 expression by promoting protein degradation, at least in part, through a GSK-3ß-dependent mechanism. Our findings suggest that iNOS-mediated decreased IRS-2 expression may contribute to the progression and/or exacerbation of ß-cell failure in diabetes.

Implications of measuring soluble receptor activators of nuclear factor-kappaB ligand and osteoprotegerin in bone metabolism of elderly women.

BACKGROUND/AIM: The discovery of a signaling system consisting of a soluble receptor activator of the NF-kappaB ligand (sRANKL) and its decoy receptor osteoprotegerin (OPG) has provided a valuable key to understanding the pathophysiology of the bone microenvironment. We conducted a cross-sectional study of the role of sRANKL and OPG levels as they relate to bone metabolism in elderly postmenopausal women with and without osteoporosis. SUBJECTS AND METHODS: Fifty-one elderly women with or without osteoporosis were enrolled in the study. Bone alkaline phosphatase, osteocalcin, urinary deoxypyridinoline and urinary type I collagen N-terminal telopeptide (NTx) were measured as bone metabolic markers. Serum levels of OPG and sRANKL were measured by sandwich enzyme-linked immunosorbent assay and the lumbar spine bone mineral density (LSBMD) with dual-energy X-ray absorptiometry. Furthermore, we compared the sRANKL and OPG levels in elderly women with and without vertebral fractures (VFs). RESULTS: In elderly postmenopausal women, there was a significant positive association between OPG levels and the T score and Z score of LSBMD (r = 0.345 and p = 0.014 for T score; r = 0.438 and p = 0.001 for Z score). sRANKL levels were not significantly correlated with T score, Z score of LSBMD, or any of the four bone metabolic markers. There were no significant differences in the sRANKL levels among the three groups (normal bone mineral density, osteopenia, and osteoporosis), but a trend toward a higher value in the osteoporosis group. The sRANKL/OPG ratio was negatively correlated with the T score and Z score of LSBMD (r = -0.336, p = 0.017; r = -0.384, p = 0.006, respectively), but not with any of the four bone metabolic markers. OPG levels in elderly women with VFs were lower than in those without VFs (p = 0.05). Multiple regression analysis showed that OPG and NTx are contributing factors to bone loss in elderly women (p = 0.014 and 0.012, respectively). CONCLUSION: The OPG level provides a good predictor of osteoporosis as well as NTx in elderly women; additionally, the findings suggest that OPG might protect elderly women from bone loss or fractures.

Primary aldosteronism due to unilateral adrenal microadenoma in an elderly patient: efficacy of selective adrenal venous sampling.

We encountered a case of drug-resistant hypertension and hypokalemia. Laboratory data suggested primary aldosteronism (PA). Computed tomography imaging appeared normal for a long duration with a left-sided nodule appearing far later; adrenal scintigraphy was first normal, and the second test showed right-sided uptake. However, a repeat selective adrenal venous sampling (SAVS) indicated a left-sided lateralization of the hypersecretion of aldosterone. Left adrenectomy was performed, and his clinical symptoms improved. The histopathological findings demonstrated the aldosterone-producing microadenoma with secondary micronodules. In conclusion, SAVS should be performed to determine the laterality of PA with obscure CT imaging.

[A case of nasal NK/T cell lymphoma presenting with bilateral giant adrenal tumors].

A 76-year-old woman presented to a clinic with fever and loss of body weight. Abdominal echogram showed bilateral adrenal swelling (left adrenal 90x80 mm, right adrenal 50x20 mm) and she was admitted to the hospital for further examination. A tumor was also found inside nasal cavity by enhanced computed tomography (CT), and abnormal uptake in the nasal cavity and adrenal gland was shown in gallium scintigraphy. Laboratory tests revealed the elevation of lactate dehydrogenase (LDH) and sIL-2R. Biopsy of the nasal tumor revealed nasal natural killer or thymus-derived (NK/T) cell lymphoma. No Epstein-Barr virus (EBV) -encoded RNA was detected in tissue. After THP-COP chemotherapy regimen, both the nasal and adrenal tumors decreased in size. However, a CT scan taken on admission revealed a pulmonary embolism. After treatment with heparin and warfarin, emboli disappeared. Chemotherapy was continued, but perforation of the small intestine occurred. Since the prognosis was poor, no operation was performed. Her condition slowly, and she died 60 days after admission. Since she had a high level of plasma ACTH (158.0 pg/ml) and normal serum cortisol (14.6 microg/dl), partial adrenal insufficiency was suspected. In addition, since her cortisol circadian rhythm was lost and cortisol levels were not completely suppressed by the 1 mg and 8 mg dexamethasone test, she met the criteria of the diagnosis of preclinical Cushing syndrome. NK/T cell lymphoma with giant adrenal tumor is extremely rare, but should be considered as one of the differential diagnoses of bilateral adrenal tumor.

[A case of Plummer disease that appeared in older old age after 10-year course of subclinical hyperthyroidism].

A 81-year-old woman with a thyroid tumor and subclinical hyperthyroidism since ten years ago was admitted to our hospital for palpitations and hyperthyroidism (FT(4) 1.75 ng/dl, FT(3) 5.37 pg/ml, TSH<0.03 microIU/ml). Although thyroid stimulating antibody (TSAb) was transiently and mildly positive, anti-TSH receptor antibody (TRAb), microsome test, and thyroid test were negative. Thyroid echogram showed an isoechoic nodule in the left lobe (33 x 42 x 22 mm) and a small nodule (10 x 15 x 9 mm) in right lobe. Thyroid scintiscan showed a hyperfunctional (hot) nodule in left thyroid lobe with suppressed uptake in the remainder of the gland. The uptake rate of thyroidal radioiodine ((123)I) in 24 hours was within the normal range (7.3%). Based on the above findings, a diagnosis of Plummer disease was made. Since she refused invasive surgical or radioiodine treatment, she was treated with 10 mg thiamazole daily. After treatment with propranolol and thiamazole, the thyrotoxic symptoms disappeared and thyroid function returned to normal level. She had osteoporosis but she had neither atrial fibrillation nor cardiac symptoms. This was a rare case of Plummer disease that appeared in extremely old age after a long course of subclinical hyperthyroidism.

Marked improvement of psychiatric symptoms after parathyroidectomy in elderly primary hyperparathyroidism.

Psychosomatic symptoms in primary hyperparathyroidism (PHPT) are various and include such conditions as obsessive-compulsive disorder, depression, anxiety, and paranoia. In the elderly the clinical features of the disease are often non-specific and difficult to diagnose. To quantify subjective symptoms of patients with hyperparathyroidism in the elderly, we determined whether these clinical manifestations resolved after surgical parathyroidectomy (PTX) in three PHPT patients over eighty years old. They were diagnosed with hypercalcemia, hypophosphatemia, high PTH concentrations, and osteoporosis. A single parathyroid adenoma was confirmed in each patient by Tc-MIBI scintigram, neck ultrasonography and computed tomographic scanning. PTX was performed in these three patients. Assessments of psychologic symptoms, using the Hamilton Rating Scale for Depression (HAM-D), serum calcium, and intact PTH were obtained before and after PTX. Mean weight of the resected adenomas was 438 +/- 138 mg (mean +/- SD). After PTX, serum calcium decreased from 11.1 +/- 0.5 to 9.2 +/- 0.5 mg/dl and intact PTH from 160.0 +/- 25.2 to 45.3 +/- 22.2 pg/ml. Total HAM-D scores in each patient decreased from 45 to 9, 17 to 1 and 15 to 5, respectively. Especially, there were marked improvements in depressive mood, psychomotor inhibition, anxiety and somatic symptoms after PTX. The quality of life in those patients was also improved by PTX. We propose here that PTX in elderly PHPT patients with psychiatric symptoms should be considered instead of oral administration, such as anti-depressants or bisphosphonates.

High mobility group protein-B1 interacts with sterol regulatory element-binding proteins to enhance their DNA binding.

Sterol regulatory element-binding proteins (SREBPs) are transcription factors that are predominately involved in the regulation of lipogenic and cholesterogenic enzyme gene expression. To identify unknown proteins that interact with SREBP, we screened nuclear extract proteins with 35S-labeled SREBP-1 bait in Far Western blotting analysis. Using this approach, high mobility group protein-B1 (HMGB1), a chromosomal protein, was identified as a novel SREBP interacting protein. In vitro glutathione S-transferase pull-down and in vivo coimmunoprecipitation studies confirmed an interaction between HMGB1 and both SREBP-1 and -2. The protein-protein interaction was mediated through the helix-loop-helix domain of SREBP-1, residues 309-344, and the A box of HMGB1. Furthermore, an electrophoretic mobility shift assay demonstrated that HMGB1 enhances SREBPs binding to their cognate DNA sequences. Moreover, luciferase reporter analyses, including RNA interference technique showed that HMGB1 potentiates the transcriptional activities of SREBP in cultured cells. These findings raise the intriguing possibility that HMGB1 is potentially involved in the regulation of lipogenic and cholesterogenic gene transcription.

Co-ordinate activation of lipogenic enzymes in hepatocellular carcinoma.

Hepatocellular carcinoma is a very common neoplastic disease in countries where hepatitis viruses B and/or C are prevalent. Small hepatocellular carcinoma lesions detected by ultrasonography at an early stage are often hyperechoic because they are composed of well-differentiated cancer cells that are rich in triglyceride droplets. The triglyceride content of hepatocytes depends in part on the rate of lipogenesis. Key lipogenic enzymes, such as fatty acid synthase, are co-ordinately regulated at the transcriptional level. We therefore examined the mRNA expression of lipogenic enzymes in human hepatocellular carcinoma samples from 10 patients who had undergone surgical resection. All of the samples exhibited marked elevation of expression of mRNA for lipogenic enzymes, such as fatty acid synthase, acetyl-CoA carboxylase and ATP citrate lyase, compared with surrounding non-cancerous liver tissue. In contrast, the changes in mRNA expression of SREBP-1, a transcription factor that regulates a battery of lipogenic enzymes, did not show a consistent trend. In some cases where SREBP-1 was elevated, the main contributing isoform was SREBP-1c rather than SREBP-1a. Thus, lipogenic enzymes are markedly induced in hepatocellular carcinomas, and in some cases SREBP-1c is involved in this activation.

Scavenger receptor expressed by endothelial cells I (SREC-I) mediates the uptake of acetylated low density lipoproteins by macrophages stimulated with lipopolysaccharide.

Scavenger receptor expressed by endothelial cells I (SREC-I) is a novel endocytic receptor for acetylated low density lipoprotein (LDL). Here we show that SREC-I is expressed in a wide variety of tissues, including macrophages and aortas. Lipopolysaccharide (LPS) robustly stimulated the expression of SREC-I in macrophages. In an initial attempt to clarify the role of SREC-I in the uptake of modified lipoproteins as well as in the development of atherosclerosis, we generated mice with a targeted disruption of the SREC-I gene by homologous recombination in embryonic stem cells. To exclude the overwhelming effect of the type A scavenger receptor (SR-A) on the uptake of Ac-LDL, we further generated mice lacking both SR-A and SREC-I (SR-A(-/-);SREC-I(-/-)) by cross-breeding and compared the uptake and degradation of Ac-LDL in the isolated macrophages. The contribution of SR-A and SREC-I to the overall degradation of Ac-LDL was 85 and 5%, respectively, in a non-stimulated condition. LPS increased the uptake and degradation of Ac-LDL by 1.8-fold. In this condition, the contribution of SR-A and SREC-I to the overall degradation of Ac-LDL was 90 and 6%, respectively. LPS increased the absolute contribution of SR-A and SREC-I by 1.9- and 2.3-fold, respectively. On the other hand, LPS decreased the absolute contribution of other pathways by 31%. Consistently, LPS did not increase the expression of other members of the scavenger receptor family such as CD36. In conclusion, SREC-I serves as a major endocytic receptor for Ac-LDL in LPS-stimulated macrophages lacking SR-A, suggesting that it has a key role in the development of atherosclerosis in concert with SR-A.

p53 involvement in the pathogenesis of fatty liver disease.

Obesity is a major health problem in industrialized societies, and fatty liver disease (hepatic steatosis) is common in obese individuals. Oxidative stress originating from increased intracellular levels of fatty acids has been implicated as a cause of hepatocellular injury in steatosis, although the precise mechanisms remain to be elucidated. p53, widely known as a tumor suppressor, has been shown often to be activated in stressed cells, inducing cell cycle arrest or death. Here we demonstrate that p53 is involved in the molecular mechanisms of hepatocellular injury associated with steatosis. We found that p53 in the nucleus is induced in the liver from two mouse models of fatty liver disease, ob/ob and a transgenic mouse model that overexpresses an active form of sterol regulatory element-binding protein-1 in the liver (TgSREBP-1), the one with obesity and the other without obesity. This activation of the p53 pathway leads to the elevation of p21 mRNA expression, which can be considered an indicator of p53 activity, because ob/ob mice lacking p53 generated by targeting gene disruption exhibited the complete restoration of the p21 elevation to wild type levels. Consistent with these results, the amelioration of hepatic steatosis caused by Srebp-1 gene disruption in ob/ob mice lowered the p21 expression in a triglyceride content-dependent manner. Moreover, p53 deficiency in ob/ob mice resulted in a marked improvement of plasma alanine aminotransferase levels, demonstrating that p53 is involved in the mechanisms of hepatocellular injury. In conclusion, we revealed that p53 plays an important role in the pathogenesis of fatty liver disease.

p53 Activation in adipocytes of obese mice.

The tumor suppressor p53 is a transcription factor that activates or represses its target genes after various genotoxic stresses. We have previously shown that sterol regulatory element-binding protein-1 (SREBP-1), a key transcriptional regulator of triglyceride synthesis, and the lipogenic enzymes under its control are markedly suppressed in adipocytes from genetically obese ob/ob mice. Here we demonstrate that p53 and its target genes are highly induced in adipocytes of ob/ob mice in a fed state, leading to the negative regulation of SREBP-1 and thereby lipogenic genes. In fact, disruption of p53 in ob/ob mice completely suppressed the p53-regulated genes to wild-type levels and partially restored expression of lipogenic enzymes. Consistently, reporter gene analysis showed that p53 overexpression suppressed the promoter activity of the SREBP-1c gene and its downstream genes. Thus, the activation of p53 might constitute a negative feedback loop against excess fat accumulation in adipocytes. In conclusion, we discovered a novel role of p53 in the pathophysiology of obesity.

Lipolysis in the absence of hormone-sensitive lipase: evidence for a common mechanism regulating distinct lipases.

Hormone-sensitive lipase (HSL) is presumed to be essential for lipolysis, which is defined as the mobilization of free fatty acids from adipocytes. In the present study, we investigated the effects of various lipolytic hormones on the lipolysis in adipocytes derived from mouse embryonic fibroblasts (MEF adipocytes) prepared from HSL-deficient mice (HSL-/-). HSL-/- MEF differentiated into mature adipocytes in a manner indistinguishable from that of wild-type mice. Both isoproterenol (ISO) and tumor necrosis factor (TNF)-alpha stimulated the rate of lipolysis in HSL-/- MEF adipocytes, although to a lesser extent than in wild-type cells, and these lipolytic activities were inhibited by H-89, a cAMP-dependent protein kinase inhibitor, and troglitazone, respectively. Thus, the responses of the residual lipolytic activity to lipolytic hormones and TNF-alpha were well conserved in the absence of HSL. Extracts from HSL-/- MEF adipocytes hydrolyzed triacylglycerol (TG) but not cholesterol ester, indicating that the residual lipolytic activity was mediated by another TG-specific lipase. The TG lipase activity, which was decreased in cytosolic fraction in response to ISO, was increased in fat cake fraction. Therefore, translocation of the TG lipase may explain, at least partially, the ISO-stimulated lipolysis in HSL-/- adipocytes. In conclusion, lipolysis is mediated not only by HSL but also by the non-HSL TG lipase, whose responses to lipolytic hormones are similar to those of HSL. We propose that both lipases are regulated by common mechanism of lipolysis.

A kindred of familial acromegaly without evidence for linkage to MEN-1 locus.

Familial acromegaly (FA) is a rare inherited disease characterized by clustering of somatotrophic adenomas and acromegaly within a family without other manifestations of multiple endocrine neoplasia-type 1 (MEN-1). The genetic basis of this pituitary-specific phenotype is largely unknown, and its relationship to the MEN-1 locus on chromosome 11q13 also remains unclear. To test the hypothesis that FA results from a germline mutation of the MEN-1 locus, we performed a linkage analysis in a Japanese family with 2 members showing manifestations of acromegaly due to somatotroph adenomas. We also examined the adenoma of one patient for loss of heterozygosity (LOH) at 11q13 locus and for the presence of mutations of codon 201 and 227 in the gene for Gsalpha. Our results provided no evidence that either germline alterations of the MEN-1 locus, LOH at 11q13, or somatic mutation of Gsalpha plays a causative role in the development of somatotroph adenomas in our FA family. Together with the previous reports, these results suggest that there are at least two distinct subgroups of FA: one that results from a mutation in MEN-1 locus and the other whose causative gene is located outside the 11q13 locus.