Differential effects of bariatric surgery and caloric restriction on hepatic one-carbon and fatty acid metabolism

Weight loss interventions, including dietary changes, pharmacotherapy, or bariatric surgery, prevent many of the adverse consequences of obesity, and may also confer intervention-specific benefits beyond those seen with decreased weight alone. We compared the molecular effects of different interventions on liver metabolism to understand the mechanisms underlying these benefits. Male rats on a high-fat, high-sucrose diet underwent sleeve gastrectomy (SG) or intermittent fasting with caloric restriction (IF-CR), achieving equivalent weight loss. The interventions were compared to ad-libitum (AL)-fed controls. Analysis of liver and blood metabolome and transcriptome revealed distinct and sometimes contrasting metabolic effects between the two interventions. SG primarily influenced one-carbon metabolic pathways, whereas IF-CR increased de novo lipogenesis and glycogen storage. These findings suggest that the unique metabolic pathways affected by SG and IF-CR contribute to their distinct clinical benefits, with bariatric surgery potentially influencing long-lasting changes through its effect on one-carbon metabolism.

Sleeve Gastrectomy Reduces Glycemia but Does Not Affect Cognitive Impairment in Lean 5xFAD Mice

Obesity and hyperglycemia are risk factors for cognitive decline and for the development of Alzheimer’s Disease (AD). Bariatric surgery is an effective treatment for obesity that was shown to improve cognitive decline in obese patients. Bariatric surgery was shown to exert weight loss independent effects on metabolic diseases such as type 2 diabetes. We tested whether sleeve gastrectomy (SG), a common bariatric surgery, can affect the cognitive impairment in lean, normoglycemic female 5xFAD mice, a genetic model for AD. 5xFAD mice and wild-type (WT) littermates underwent SG or sham surgery at the age of 5 months and were tested for metabolic, behavioral, and molecular phenotypes 90 days later. SG led to a reduction in blood glucose levels and total plasma cholesterol levels in 5xFAD mice without inducing weight loss. However, the surgery did not affect the outcomes of long-term spatial memory tests in these mice. Analysis of β-Amyloid plaques corroborated the behavioral studies in showing no effect of surgery on the molecular phenotype of 5xFAD mice. In conclusion, SG leads to an improved metabolic profile in lean female 5xFAD mice without inducing weight loss but does not affect the brain pathology or behavioral phenotype. Our results suggest that the positive effects of bariatric surgery on cognitive decline in obese patients are likely attributed to weight loss and improvement in obesity sequelae, and not to weight loss independent effects of surgery.

Generation and characterization of a mouse model for one anastomosis gastric bypass surgery

One anastomosis gastric bypass (OAGB) surgery became a common bariatric procedure in recent years. In this surgery, the distal stomach, duodenum, and proximal jejunum are bypassed, leading to weight loss, improvement in metabolic parameters, and a change in hormonal secretion. We sought to generate and characterize a mouse model for OAGB. Mice fed for 26 wk on a high-fat diet were assigned to OAGB, sham surgery, or caloric restriction and were followed for 50 more days on a high-fat diet. Physiological and histological parameters of the mice were compared during and at the end of the experiment. OAGB-operated mice lost weight and displayed low levels of plasma lipids, high insulin sensitivity, and rapid glucose metabolism compared with sham-operated mice. OAGB-operated mice had higher energy expenditure, higher levels of glucagon-like peptide (GLP-1), and lower albumin than weight-matched calorie-restricted mice. There was no difference in the histology of the endocrine pancreas. The livers of OAGB mice had little hepatic steatosis yet presented with a large number of phagocytic cells. The OAGB mouse model recapitulates many of the phenotypes described in patients that underwent OAGB and enables molecular and physiological studies on the outcome of this surgery.NEW & NOTEWORTHY A mouse model for one anastomosis gastric bypass (OAGB) surgery displays similar outcomes to clinical reports and enables to study the weight loss-dependent and -independent effects of this bariatric surgery.

Maternal antagonism of Glp1 reverses the adverse outcomes of sleeve gastrectomy on mouse offspring

Mothers that underwent bariatric surgery are at higher risk for delivering a small-for-gestational age (SGA) infant. This phenomenon is attributed to malabsorption and rapid weight loss following surgery. We compared pregnancy outcomes in lean mice that underwent sham surgery or sleeve gastrectomy (SG). SG led to a reduction in glucose levels and an increase in postprandial levels of glucagon-like peptide 1 (Glp1) without affecting mice weight during pregnancy. Pups of SG-operated mice (SG pups) were born SGA. The placenta and pancreas of the pups were not affected by SG, although a high-fat diet caused hepatic steatosis and glucose intolerance in male SG pups. Treatment with a Glp1 receptor antagonist during pregnancy normalized the birth weight of SG pups and diminished the adverse response to a high-fat diet without affecting glucose levels of pregnant mice. The antagonist did not affect the birth weight of pups of sham-operated mice. Our findings link elevated Glp1 signaling, rather than weight loss, to the increased prevalence of SGA births following bariatric surgery with metabolic consequences for the offspring. The long-term effects of bariatric surgery on the metabolic health of offspring of patients require further investigation.

Sleeve Gastrectomy Suppresses Hepatic Glucose Production and Increases Hepatic Insulin Clearance Independent of Weight Loss

Bariatric operations induce weight loss, which is associated with an improvement in hepatic steatosis and a reduction in hepatic glucose production. It is not clear whether these outcomes are entirely due to weight loss, or whether the new anatomy imposed by the surgery contributes to the improvement in the metabolic function of the liver. We performed vertical sleeve gastrectomy (VSG) on obese mice provided with a high-fat high-sucrose diet and compared them to diet and weight-matched sham-operated mice (WMS). At 40 days after surgery, VSG-operated mice displayed less hepatic steatosis compared with WMS. By measuring the fasting glucose and insulin levels in the blood vessels feeding and draining the liver, we showed directly that hepatic glucose production was suppressed after VSG. Insulin levels were elevated in the portal vein, and hepatic insulin clearance was elevated in VSG-operated mice. The hepatic expression of genes associated with insulin clearance was upregulated. We repeated the experiment in lean mice and observed that portal insulin and glucagon are elevated, but only insulin clearance is increased in VSG-operated mice. In conclusion, direct measurement of glucose and insulin in the blood entering and leaving the liver shows that VSG affects glucose and insulin metabolism through mechanisms independent of weight loss and diet.

Excimer laser phototherapeutic keratectomy for recurrent corneal erosion

PURPOSE

To evaluate the outcome of excimer laser phototherapeutic keratectomy (PTK) for recurrent corneal erosion.

SETTING

Laser Institute, Assay Harofeh Medical Center, Zerifin, Israel.

METHODS

Twenty-three patients with a mean age of 50.56 years +/- 13.87 (SD) were referred between 1991 and 1995 for recurrent corneal erosion that did not respond to conservative treatment. All were treated by excimer laser PTK. Patients were interviewed and examined before and after treatment.

RESULTS

Disease duration ranged from 2 months to 10 years. Frequency of attacks ranged from weekly to three to four times a year. Re-epithelialization of the cornea was established within an average of 3 days after PTK treatment. Follow-up was 12 to 60 months (mean 38.43 +/- 12.08 months). Nineteen (83%) patients were free of recurrences, and 3 had one recurrence treated successfully by patching. One patient who had two recurrences had a second PTK procedure and was symptom free for 14 months. No patient reported reduced visual acuity or quality. Postoperative best corrected visual acuity was unaltered in 21 eyes and improved in 2. There was no significant difference between preoperative and postoperative manifest refractions.

CONCLUSION

Excimer laser PRK appears to be a safe and effective treatment for recurrent erosions of the cornea.

Corneal thickness and curvature in normal-tension glaucoma

PURPOSE

To determine whether normal-tension glaucoma, defined as a condition in which glaucomatous optic nerve and visual field changes exist without documentation of intraocular pressure greater than 21 mm Hg or other apparent cause for these changes, is overdiagnosed in patients with decreased central corneal thickness and curvature.

METHODS

Twenty-one patients with normal-tension glaucoma were compared with 25 patients with primary open-angle glaucoma and 27 age-matched healthy subjects. Corneal thickness was determined by ultrasonic pachymetry. Corneal curvature was determined using a keratometer. Eyes with corneal pathology or previous intraocular surgery were excluded.

RESULTS

Mean corneal thickness +/- SD in 21 eyes of 21 patients with normal-tension glaucoma was 0.521 +/- 0.037 mm, significantly (P = .0028) lower than in 25 eyes of 25 patients with primary open-angle glaucoma (0.556 +/- 0.035 mm) and 27 eyes of 27 healthy subjects (0.555 +/- 0.034). Mean corneal curvature in the three groups was not appreciably different: 43.90 +/- 1.81 diopters, 43.66 +/- 1.68 diopters, and 44.36 +/- 1.13 diopters in the patients with normal-tension glaucoma and primary open-angle glaucoma and the healthy subjects, respectively.

CONCLUSIONS

Corneal thickness is significantly reduced in patients with normal-tension glaucoma compared with patients with primary open-angle glaucoma (P = .0028) and normal subjects (P = .0037). This may lead to underestimation of intraocular pressure and misdiagnosis in some of these patients. Corneal curvature was similar in patients with normal-tension glaucoma and primary open-angle glaucoma and in healthy subjects.

For how long can regression continue after photorefractive keratectomy for myopia?

PURPOSE

The presence and degree of regression were assessed from 18 to 30 months after photorefractive keratectomy (PRK).

METHODS

A total of 449 eyes (449 patients) were treated with an Aesculap Meditec 193-nm Arf Excimer laser. These 449 eyes were followed during the first 24 months after PRK, and 252 of these eyes were followed for 24 to 30 months.

RESULTS

Thirty (6.7%) of the 449 eyes followed for up to 24 months showed good refractive results during the first year and a half but regressed thereafter and required retreatment. Late regression was confined to subjects with pretreatment myopia above -4.0 diopters (D) and was the same in low- and high-myopic eyes between 18 and 24 months post-PRK. However, between 24 and 30 months, regression was higher in low-myopic eyes, where it reached -0.55 D, than in high-myopic eyes, where it was -0.21 D. This lower frequency of regression in high-myopic eyes is attributed to the relatively high rate of retreatment in this group during the first 18 months after PRK.

CONCLUSIONS

Although the findings indicate a fairly low rate of regression after 24 months, there still are insufficient data on which to predict when regression post-PRK stabilizes.

Influence of patient age on refraction and corneal haze after photorefractive keratectomy

AIMS/BACKGROUND

Since wound healing processes are known to be more rapid in those who are young, it was decided to examine the effect of patient age on refractive outcome of photorefractive keratectomy (PRK).

METHODS

The records of 599 eyes that had undergone PRK were studied retrospectively. The eyes were categorised by baseline myopia and patient age. Spherical equivalent and corneal haze were compared in the baseline refraction and age groups at 3, 6, and 12 months after PRK.

RESULTS

There were no differences in postoperative refraction and corneal haze in the different age groups.

CONCLUSION

Patient age had no statistically significant effect on refraction and corneal haze 1 year after PRK.

[Laser photorefractive surgery]

As photorefractive keratectomy (PRK) with excimer laser gains world-wide acceptance, more patients are able to discard their spectacles. Our study comprised 611 eyes which underwent PRK and were followed for at least a year. Those with myopia up to -6.00D had better post-operative visual acuity and refraction, than patients with higher grades of myopia. They had less corneal haze and a greater proportion were satisfied with their results. Complaints of halos and glare were similar at all degrees of myopia up to -10.00D.

Normal heterophoric changes: 20 years' follow-up

BACKGROUND

Evaluation of changes in the heterophoric condition of 100 normal individuals over a 20-year period.

METHODS

A retrospective study was undertaken. Charts of 100 normal men were reviewed. Individual changes in the heterophoric status were recorded over a 20-year period. The average value of the phoria at age 18-22 years was compared with the average value at age 34-38 years. Measurements were taken for near and distance fixation. No one was heterotropic. Changes in convergence and accommodation were also calculated.

RESULTS

A 0.9 +/- 1.7 prism diopter increase in esophoria for distance fixation and a 0.6 +/- 2.5 prism diopter increase in exophoria for near fixation were found. These changes were statistically significant (P < 0.001 and P < 0.02 respectively). The near point of convergence receded by 0.5 +/- 1.1 cm (P < 0.001), and a decrease in accommodation over time of 2.8 +/- 1.4 diopters was found (P < 0.001).

CONCLUSION

An increase in esophoria for distance fixation and a exophoria for near fixation was found in a 20-year follow-up of 100 normal subjects.

Refractory intraocular pressure increase after photorefractive keratectomy

A patient with developmental angle anomaly developed a corticosteroid-induced refractory increase in intraocular pressure (IOP) after photorefractive keratectomy (PRK). Trabeculectomy was required to reduce the pressure. Although rare, corticosteroid-induced refractory IOP increase is a serious complication of PRK and may necessitate trabeculectomy. More frequent monitoring of IOP in post-PRK patients and a re-evaluation of postoperative treatment are indicated.

Results of a repeated excimer laser photorefractive keratectomy for myopia

BACKGROUND AND OBJECTIVE

As photorefractive keratectomy (PRK) becomes more widely used, the incidence of repeated PRK increases. The present study was conducted to evaluate results of repeated PRK in view of the meager data on this topic.

PATIENTS AND METHODS

In this retrospective study, the authors reviewed the records of 1028 eyes that had undergone PRK, and analyzed the results of 66 eyes that required a second PRK for undercorrection according to baseline refraction.

RESULTS

A second PRK was performed in 6.3%, 13.7%, and 10.1% of low, moderate, and high myopes, respectively. The mean refraction 1 year after repeated PRK was similar in both myopic groups: less than -1.00 D. Of the low myopes, 87.50% had residual refraction within 1 D after 1 year. Of the moderate myopes, 88.23% had residual refraction within 1 D after 1 year. All of the low myopes achieved uncorrected visual acuity (VA) of 20/25 or better 1 year after repeated PRK, compared with 58.82% of the moderate myopes. Loss of best-corrected VA never exceeded two lines.

CONCLUSION

The overall results of PRK appear to be satisfactory.

Early and late postoperative application of 5-fluorouracil following trabeculectomy in refractory glaucoma

Intraocular pressure (IOP) control was studied retrospectively in two groups of 14 consecutive patients following trabeculectomy with adjunctive postoperative 5-fluorouracil (5-FU) treatment. In one of the groups (the early-treatment group), 5-FU injections were started 2.4 +/- 0.6 days postoperatively; in the other group (the delayed-treatment group), they were started only when clinical signs suggested impending bleb failure (12.6 +/- 5.4 days postsurgery). The patients in the two groups were age-matched and had a similar history of previous failed glaucoma operations or diabetes, both of which are considered indications for postoperative 5-FU injections. The mean number of 5-FU injections and the total dose in the two groups did not differ significantly (5.3 +/- 0.8 and 5.5 +/- 1.1 injections, respectively; 26.4 +/- 3.9 and 27.5 +/- 5.3 mg 5-FU total dose, respectively). The average follow up for the two groups was 16.7 +/- 2.5 and 16.9 +/- 2.7 months, respectively. With an IOP of 18 mm Hg or less with or without medications considered a success, 42.8% of the delayed-treatment and 71.4% of the early-treatment cases were successful. More medications were required in the early-treatment group. Postoperative transient corneal epithelial defects occurred in 71.4% and 78.4% of the eyes in the late- and early-treatment groups, respectively, an insignificant difference. Conjunctival wound leak occurred in one patient (in the delayed-treatment group).(ABSTRACT TRUNCATED AT 250 WORDS)