Maternal Mineral and Bone Metabolism During Pregnancy, Lactation, and Post-Weaning Recovery.

During pregnancy and lactation, female physiology adapts to meet the added nutritional demands of fetuses and neonates. An average full-term fetus contains ∼30 g calcium, 20 g phosphorus, and 0.8 g magnesium. About 80% of mineral is accreted during the third trimester; calcium transfers at 300-350 mg/day during the final 6 wk. The neonate requires 200 mg calcium daily from milk during the first 6 mo, and 120 mg calcium from milk during the second 6 mo (additional calcium comes from solid foods). Calcium transfers can be more than double and triple these values, respectively, in women who nurse twins and triplets. About 25% of dietary calcium is normally absorbed in healthy adults. Average maternal calcium intakes in American and Canadian women are insufficient to meet the fetal and neonatal calcium requirements if normal efficiency of intestinal calcium absorption is relied upon. However, several adaptations are invoked to meet the fetal and neonatal demands for mineral without requiring increased intakes by the mother. During pregnancy the efficiency of intestinal calcium absorption doubles, whereas during lactation the maternal skeleton is resorbed to provide calcium for milk. This review addresses our current knowledge regarding maternal adaptations in mineral and skeletal homeostasis that occur during pregnancy, lactation, and post-weaning recovery. Also considered are the impacts that these adaptations have on biochemical and hormonal parameters of mineral homeostasis, the consequences for long-term skeletal health, and the presentation and management of disorders of mineral and bone metabolism.

Proceedings of the 2023 Santa Fe Bone Symposium: Progress and Controversies in the Management of Patients with Skeletal Diseases.

The Santa Fe Bone Symposium (SFBS) held its 23rd annual event on August 5-6, 2023, in Santa Fe, New Mexico, USA. Attendees participated in-person and remotely, representing many states and countries. The program included plenary presentations, panel discussions, satellite symposia, a Project ECHO workshop, and a session on healthcare policy and reimbursement for fracture liaison programs. A broad range of topics were addressed, including transitions of osteoporosis treatments over a lifetime; controversies in vitamin D; update on Official Positions of the International Society for Clinical Densitometry; spine surgery and bone health; clinical applications of bone turnover markers; basic bone biology for clinicians; premenopausal-, pregnancy-, and lactation-associated osteoporosis; cancer treatment induced bone loss in patients with breast cancer and prostate cancer; genetic testing for skeletal diseases; and an update on nutrition and bone health. There were also sessions on rare bone diseases, including managing patients with hypophosphatasia; treatment of X-linked hypophosphatemia; and assessment and treatment of patients with hypoparathyroidism. There were oral presentations of abstracts by endocrinology fellows selected from those who participated in the Santa Fe Fellows Workshop on Metabolic Bone Diseases, held the 2 days prior to the SFBS. These proceedings of the 2023 SFBS present the clinical highlights and insights generated from many formal and informal discussions in Santa Fe.

Bone development and mineral homeostasis in the fetus and neonate: roles of the calciotropic and phosphotropic hormones.

Mineral and bone metabolism are regulated differently in utero compared with the adult. The fetal kidneys, intestines, and skeleton are not dominant sources of mineral supply for the fetus. Instead, the placenta meets the fetal need for mineral by actively transporting calcium, phosphorus, and magnesium from the maternal circulation. These minerals are maintained in the fetal circulation at higher concentrations than in the mother and normal adult, and such high levels appear necessary for the developing skeleton to accrete a normal amount of mineral by term. Parathyroid hormone (PTH) and calcitriol circulate at low concentrations in the fetal circulation. Fetal bone development and the regulation of serum minerals are critically dependent on PTH and PTH-related protein, but not vitamin D/calcitriol, fibroblast growth factor-23, calcitonin, or the sex steroids. After birth, the serum calcium falls and phosphorus rises before gradually reaching adult values over the subsequent 24-48 h. The intestines are the main source of mineral for the neonate, while the kidneys reabsorb mineral, and bone turnover contributes mineral to the circulation. This switch in the regulation of mineral homeostasis is triggered by loss of the placenta and a postnatal fall in serum calcium, and is followed in sequence by a rise in PTH and then an increase in calcitriol. Intestinal calcium absorption is initially a passive process facilitated by lactose, but later becomes active and calcitriol-dependent. However, calcitriol's role can be bypassed by increasing the calcium content of the diet, or by parenteral administration of calcium.

Letermovir treatment of cytomegalovirus infection or disease in solid organ and hematopoietic cell transplant recipients.

BACKGROUND: Few options are available for cytomegalovirus (CMV) treatment in transplant recipients resistant, refractory, or intolerant to approved agents. Letermovir (LET) is approved for prophylaxis in hematopoietic cell transplant (HCT) recipients, but little is known about efficacy in CMV infection. We conducted an observational study to determine the patterns of use and outcome of LET treatment of CMV infection in transplant recipients. METHODS: Patients who received LET for treatment of CMV infection were identified at 13 transplant centers. Demographic and outcome data were collected. RESULTS: Twenty-seven solid organ and 21 HCT recipients (one dual) from 13 medical centers were included. Forty-five of 47 (94%) were treated with other agents prior to LET, and 57% had a history of prior CMV disease. Seventy-seven percent were intolerant to other antivirals; 32% were started on LET because of resistance concerns. Among 37 patients with viral load < 1000 international units (IU)/ml at LET initiation, two experienced >1 log rise in viral load by week 12, and no deaths were attributed to CMV. Ten patients had viral load > 1000 IU/ml at LET initiation, and six of 10 (60%) had a CMV viral load < 1000 IU/ml at completion of therapy or last known value. LET was discontinued in two patients for an adverse event. CONCLUSIONS: Patients treated with LET with viral load < 1000 IU/ml had good virologic outcomes. Outcomes were mixed when LET was initiated at higher viral loads. Further studies on combination therapy or alternative LET dosing are needed.

Vertebral Fractures: Which Radiological Criteria Are Better Associated With the Clinical Course of Osteoporosis?

STUDY PURPOSE: Morphometric methods categorize potential osteoporotic vertebral fractures (OVF) on the basis of loss of vertebral height. A particular example is the widely used semiquantitative morphometric tool proposed by Genant (GSQ). A newer morphologic algorithm-based qualitative (mABQ) tool focuses on vertebral end-plate damage in recognizing OVF. We used data from both sexes in the Canadian Multicentre Osteoporosis Study (CaMos) to compare the 2 methods in identifying OVF at baseline and during 10 years of follow-up. MATERIALS AND METHODS: We obtained lateral thoracic and lumbar spinal radiographs (T4-L4) 3 times, at 5-year intervals, in 828 participants of the population-based CaMos. Logistic regressions were used to study the association of 10-year changes in bone mineral density (BMD) with incident fractures. RESULTS: At baseline, 161 participants had grade 1 and 32 had grade 2 GSQ OVF; over the next 10 years, only 9 of these participants had sustained incident GSQ OVF. Contrastingly, 21 participants at baseline had grade 1 and 48 grade 2 mABQ events; over the next 10 years, 79 subjects experienced incident grade 1 or grade 2 mABQ events. Thus, incident grades 1 and 2 morphologic fractures were 8 times more common than morphometric deformities alone. Each 10-year decrease of 0.01 g/cm2 in total hip BMD was associated with a 4.1% (95% CI: 0.7-7.3) higher odds of having an incident vertebral fracture. CONCLUSIONS: This analysis further suggests that morphometric deformities and morphologic fractures constitute distinct entities; morphologic fractures conform more closely to the expected epidemiology of OVF.

Disruption of l-Rhamnose Biosynthesis Results in Severe Growth Defects in Streptococcus mutans.

The rhamnose-glucose cell wall polysaccharide (RGP) of Streptococcus mutans plays a significant role in cell division, virulence, and stress protection. Prior studies examined function of the RGP using strains carrying deletions in the machinery involved in RGP assembly. In this study, we explored loss of the substrate for RGP, l-rhamnose, via deletion of rmlD (encoding the protein responsible for the terminal step in l-rhamnose biosynthesis). We demonstrate that loss of rhamnose biosynthesis causes a phenotype similar to strains with disrupted RGP assembly (ΔrgpG and ΔrgpF strains). Deletion of rmlD not only caused a severe growth defect under nonstress growth conditions but also elevated susceptibility of the strain to acid and oxidative stress, common conditions found in the oral cavity. A genetic complement of the ΔrmlD strain completely restored wild-type levels of growth, whereas addition of exogenous rhamnose did not. The loss of rhamnose production also significantly disrupted biofilm formation, an important aspect of S. mutans growth in the oral cavity. Further, we demonstrate that loss of either rmlD or rgpG results in ablation of rhamnose content in the S. mutans cell wall. Taken together, these results highlight the importance of rhamnose production in both the fitness and the ability of S. mutans to overcome environmental stresses.IMPORTANCEStreptococcus mutans is a pathogenic bacterium that is the primary etiologic agent of dental caries, a disease that affects billions yearly. Rhamnose biosynthesis is conserved not only in streptococcal species but in other Gram-positive, as well as Gram-negative, organisms. This study highlights the importance of rhamnose biosynthesis in RGP production for protection of the organism against acid and oxidative stresses, the two major stressors that the organism encounters in the oral cavity. Loss of RGP also severely impacts biofilm formation, the first step in the onset of dental caries. The high conservation of the rhamnose synthesis enzymes, as well as their importance in S. mutans and other organisms, makes them favorable antibiotic targets for the treatment of disease.

Streptococcus mutans requires mature rhamnose-glucose polysaccharides for proper pathophysiology, morphogenesis and cellular division.

The cell wall of Gram-positive bacteria has been shown to mediate environmental stress tolerance, antibiotic susceptibility, host immune evasion and overall virulence. The majority of these traits have been demonstrated for the well-studied system of wall teichoic acid (WTA) synthesis, a common cell wall polysaccharide among Gram-positive organisms. Streptococcus mutans, a Gram-positive odontopathogen that contributes to the enamel-destructive disease dental caries, lacks the capabilities to generate WTA. Instead, the cell wall of S. mutans is highly decorated with rhamnose-glucose polysaccharides (RGP), for which functional roles are poorly defined. Here, we demonstrate that the RGP has a distinct role in protecting S. mutans from a variety of stress conditions pertinent to pathogenic capability. Mutant strains with disrupted RGP synthesis failed to properly localize cell division complexes, suffered from aberrant septum formation and exhibited enhanced cellular autolysis. Surprisingly, mutant strains of S. mutans with impairment in RGP side chain modification grew into elongated chains and also failed to properly localize the presumed cell wall hydrolase, GbpB. Our results indicate that fully mature RGP has distinct protective and morphogenic roles for S. mutans, and these structures are functionally homologous to the WTA of other Gram-positive bacteria.

Impact of asymptomatic bacteriuria incidence and management post-kidney transplantation.

OBJECTIVE: Urinary tract infections (UTIs) are the most commonly occurring infectious complication following kidney transplantation. Questions remain regarding whether asymptomatic bacteriuria (ASB) should be treated. The aim was to evaluate the incidence and management of ASB in kidney transplant recipients at a large academic medical center. METHODS: All subjects receiving an isolated kidney transplant between September 2012 and October 2016, and with at least one ASB episode were included. Demographics, symptomatology, and urine culture data were collected on subjects with bacteriuria in the first year post-transplant. Cultures were classified by symptoms, ASB treatment trends were analyzed, and ASB-to-UTI progression was compared between ASB treatment and non-treatment. RESULTS: A total of 527 subjects were transplanted with 64 developing at least one ASB episode. The incidence of ASB was 12.1% and treated 74.6% of the time. Neither lack of ASB treatment (P = 0.463) nor ASB within the first month post-transplant (P = 0.303) were associated with ASB-to-UTI progression. CONCLUSION: Despite high ASB treatment rate, this was not found to be protective against ASB-to-UTI progression. ASB within the first month post-transplant also did not correlate with increased progression risk. These results suggest minimization of ASB treatment in kidney transplant recipients remains an important antimicrobial stewardship target.

Penicillin allergy skin testing as an antibiotic stewardship intervention reduces alternative antibiotic exposures in hematopoietic stem cell transplant recipients.

BACKGROUND: Antibiotic allergy de-labeling using penicillin allergy skin testing (PAST) can reduce the use and cost of alternative, non-ß-lactam antibiotics in general inpatient populations. This strategy's role in hematopoietic stem cell transplant (HSCT) recipients is unclear. METHODS: This study aimed to determine the effect of a pre-transplant PAST protocol on antibiotic use, days of therapy (DOT), and cost in an immunocompromised population at a single center from 7/1/2010-2/1/2019. Patients who received chimeric antigen receptor (CAR) T-cell therapy and those who underwent transplantation in the outpatient setting were excluded. RESULTS: Of 1560 patients who underwent inpatient HSCT during the study period, 208 reported ß-lactam allergy (136/844 [16%] pre- and 72/716 [10%] post-implementation; P < .001). PAST was performed on 7% and 54% of HSCT recipients pre- and post-implementation, respectively. Only two positive PAST were noted. There were no adverse reactions to PAST. There were no significant differences in the disease and transplant characteristics between the two groups. Days of therapy and cost of alternative antibiotics significantly decreased post-implementation (mean 788 vs 627 days, P = .01; mean $24 425 vs $17 518, P = .009). CONCLUSION: Penicillin allergy skin testing adjudicates reported ß-lactam allergy in HSCT recipients, lowering use, DOT, and cost of alternative antibiotics and promoting effective formulary agents to treat immunocompromised HSCT recipients.

Cystic neutrophilic granulomatous mastitis: The Cleveland Clinic experience with diagnosis and management.

Granulomatous mastitis is an uncommon inflammatory disease that typically presents with painful breast lesions. Recent publications have brought to light a specific subset of granulomatous mastitis patients with a distinct histological pattern of disease termed, "cystic neutrophilic granulomatous mastitis" (CNGM). Although many cases of granulomatous lobular mastitis have been thought to be idiopathic, this rare subset of an uncommon disease has been linked to infections with Corynebacterium species. Herein, a cohort of CNGM patients from a large, tertiary care, North-American, academic medical center is presented. Correlative demographic, clinical, radiographic, pathologic, microbiologic, management, and outcomes data are provided. Collaborative communication between specialists to accurately diagnose and manage these patients is essential to decreasing potential morbidity.

Combined hormonal contraceptives use and bone mineral density changes in adolescent and young women in a prospective population-based Canada-wide observational study.

OBJECTIVES: To assess combined hormonal contraceptives (CHC) use and adolescent women's peak areal bone mineral density (BMD) accrual. METHODS: We enrolled 527 randomly selected women across Canada (2004-6) divided by age into adolescents (16-19) and young adults (20-24) and by CHC use to ever (E-CHC)/never (N-CHC) users. At baseline and year 2 we measured height, weight, and BMD at lumbar spine (L1-4), femoral neck, and total hip sites. Interviewer-administered questionnaires addressed menarche age, cigarette and alcohol use, calcium/vitamin D intakes, physical activity and estrogen dose (≤30/>30 micrograms). Linear regression models examined associations of CHC use with 2-year BMD change adjusted for bone-related variables. RESULTS: Of 307 women with complete data, 229 (75%) used CHC. N-CHC adolescents gained significantly more unadjusted total hip BMD +0.012 g/cm2/2-y (95% C.I.: 0.001, 0.023) with similar trends at all sites. N-CHC adolescents tended to have greater adjusted femoral neck BMD gain: mean difference +0.009 g/cm2 (95% CI: -0.002; 0.021). In young women N-CHC, however, adjusted femoral neck BMD decreased significantly more -0.021 g/cm2 (95%CI: -0.006; -0.036) with similar trends at other sites. BMD changes were unrelated to estrogen dose and age at starting CHC. CONCLUSIONS: Adolescent CHC users in a random population demonstrated less hip region peak BMD accrual than non-users. This requires randomized control trial confirmation.

Densitometer-Specific Differences in the Correlation Between Body Mass Index and Lumbar Spine Trabecular Bone Score.

Trabecular bone score (TBS) is a gray-level texture measure derived from lumbar spine dual-energy X-ray absorptiometry (DXA) images that predicts fractures independent of bone mineral density (BMD). Increased abdominal soft tissue in individuals with elevated body mass index (BMI) absorbs more X-rays during image acquisition for BMD measurement and must be accommodated by the TBS algorithm. We aimed to determine if the relationship between BMI and TBS varied between 2 major manufacturers' densitometers, because different densitometers accommodate soft tissues differently. We identified 1919 women and 811 men, participants of the Canadian Multicentre Osteoporosis Study, aged ≥40 yr with lumbar spine DXA scans acquired on GE Lunar (4 centers) or Hologic (3 centers) densitometers at year 10 of follow-up. TBS was calculated for L1-L4 (TBS iNsight® software, version 2.1). A significant negative correlation between TBS and BMI was observed when TBS measurements were performed on Hologic densitometers in men (Pearson r = -0.36, p <0.0001) and in women (Pearson r = -0.33, p <0.0001); significant correlations were not seen when TBS was measured on GE Lunar densitometers (Pearson r = 0.00 in men, Pearson r = -0.02 in women). Age-adjusted linear regression models confirmed significant interactions between BMI and densitometer manufacturer for both men and women (p < 0.0001). In contrast, comparable positive correlations were observed between BMD and BMI on both Hologic and GE Lunar densitometers in men and women. In conclusion, BMI significantly affects TBS values in men and women when measured on Hologic but not GE Lunar densitometers. This finding has implications for clinical and research applications of TBS, especially when TBS is measured sequentially on DXA densitometers from different manufacturers or when results from different machines are pooled for analysis.

The Newfoundland and Labrador Bariatric Surgery Cohort Study: Rational and Study Protocol.

BACKGROUND: In Canada, there has been a disproportionate increase in adults with Class II (BMI 35.0-39.9 kg/m2) or Class III obesity (BMI ≥ 40 kg/m2) affecting 9 % of Canadians with increases projected. Individuals affected by severe obesity (BMI ≥ 35) are at increased risk of high blood pressure, cardiovascular disease, diabetes, cancer, impaired quality of life, and premature mortality. Bariatric surgery is the most effective treatment for severe obesity. Laparoscopic sleeve gastrectomy (LSG), a relatively new type of bariatric surgery, is growing in popularity as a treatment. The global prevalence of LSG increased from 0 to 37.0 % between 2003 and 2013. In Canada and the US, between 2011 and 2013, the number of LSG surgeries increased by 244 % and LSG now comprises 43 % of all bariatric surgeries. Since 2011, Eastern Health, the largest regional health authority in Newfoundland and Labrador (NL), Canada has performed approximately 100 LSG surgeries annually. METHODS: A population-based prospective cohort study with pre and post surgical assessments at 1, 3, 6, 12, 18, 24 months and annually thereafter of patients undergoing LSG. This study will report on short - to mid-term (2-4 years) outcomes. Patients (n = 200) followed by the Provincial Bariatric Surgery Program between 19 and 70 years of age, with a BMI between 35.0 and 39.9 kg/m2 and an obesity-related comorbidity or with a BMI ≥ 40 kg/m2 are enrolled. The study is assessing the following outcomes: 1) complications of surgery including impact on nutritional status 2) weight loss/regain 3) improvement/resolution of comorbid conditions and a reduction in prescribed medications 4) patient reported outcomes using validated quality of life tools, and 5) impact of surgery on health services use and costs. We hypothesize a low complication rate, a marked reduction in weight, improvement/resolution of comorbid conditions, a reduction in related medications, improvement in quality of life, and a decrease in direct healthcare use and costs and indirect costs compared to pre-surgery. DISCUSSION: Limited data on the impact of LSG as a stand-alone procedure on a number of outcomes exist. The findings from this study will help to inform evidence-based practice, clinical decision-making, and the development of health policy.

Impact of pretransplant rifaximin therapy on early post-liver transplant infections.

Bacterial and fungal infections are major causes of morbidity and mortality after liver transplantation (LT). The role of intestinal decontamination in the prevention of post-LT infections is controversial. Rifaximin is widely used for the treatment of hepatic encephalopathy. The effect of rifaximin on post-LT infections is unknown. The aim of our study was to determine the effect of rifaximin therapy in the pretransplant period on early bacterial infections (EBIs) and fungal infections within the first 30 days after LT. All adult patients who underwent LT at our institution (January 2009 to July 2011) were included in this retrospective cohort study. Patients receiving antibiotics other than pretransplant protocol antibiotics were excluded. Patients were stratified into 2 groups based on the presence or absence of rifaximin therapy for at least 2 days before LT. Infections were defined by the isolation of any bacterial or fungal organisms within 30 days of LT. Multivariate regression analysis, Student t tests, and Pearson's chi-square tests were used to compare the 2 groups. Two hundred sixty-eight patients were included, and 71 of these patients (26.5%) were on rifaximin at the time of LT. The 2 groups were comparable with respect to age, sex, race, and Model for End-Stage Liver Disease score. There were no significant differences in the rates of EBIs (30% for the non-rifaximin group and 25% for the rifaximin group, P = 0.48) or fungal infections between the 2 groups. There was no increase in antimicrobial resistance among the infecting organisms. There was no difference in survival between the rifaximin and non-rifaximin groups (98% versus 97%, P = 0.36). In conclusion, the use of rifaximin in the pre-LT period was not associated with an increased risk of bacterial or fungal infections in the early post-LT period.

Effect of Anticholinergic Medications on Falls, Fracture Risk, and Bone Mineral Density Over a 10-Year Period.

BACKGROUND: Many medications used in older adults have strong anticholinergic (ACH) properties, which may increase the risk of falls and fractures. Use of these medications was identified in a population-based Canadian cohort. OBJECTIVE: To identify the fall and fracture risk associated with ACH medication use. METHODS: Data collection and analysis were conducted at baseline, year 5, and year 10. Cross-sectional analyses were performed to examine associations between ACH medication use and falls. Time-dependent Cox regression was used to examine time to first nontraumatic fracture. Finally, change in bone mineral density (BMD) over 10 years was compared in ACH medication users versus nonusers. RESULTS: Strongly ACH medications were used by 618 of 7753 participants (8.0%) at study baseline, 592 (9.5%) at year 5, and 334 (7.7%) at year 10. Unadjusted ACH medication use was associated with falls at baseline (odds ratio = 1.50; 95% CI = 1.14-1.98; P = 0.004), but the association was no longer significant after covariate adjustment. Similar results occurred at years 5 and 10. ACH medication use was associated with increased incident fracture risk before (hazard ratio = 1.22; CI = 1.13-1.32; P < 0.001) but not after covariate adjustment. Mean (SD) change in femoral neck BMD T-score over 10 years, in those using ACH medications at both years 0 and 5, was -0.60 (0.63) in ACH users versus -0.49 (0.45) in nonusers (P = 0.041), but this was not significant after covariate adjustment. CONCLUSIONS: ACH medications were not found to be independently associated with an increased risk of falling, fractures, or BMD loss. Rather, factors associated with ACH medication use explained the apparent associations.

Bone metabolism in the fetus and neonate.

During embryonic development most of the skeleton begins as a cartilaginous scaffold that is progressively resorbed and replaced by bone. Such endochondral bone development does not cease until the growth plates fuse during puberty. Growth and mineralization of the skeleton are dependent upon the adequate delivery of mineral. During fetal development, the placenta actively transports calcium, magnesium and phosphorus from the maternal circulation. After birth, the role of mineral transport is assumed by the intestines. The limited data currently available on fetal humans are largely based on cord blood samples from normal fetuses and pathological specimens from fetuses which died in utero or at birth. Consequently, much of our understanding of the regulation of fetal mineral and bone homeostasis comes from the study of animal fetuses that have been manipulated surgically, pharmacologically and genetically. Animal and human data indicate that fetal mineral homeostasis requires parathyroid hormone (PTH) and PTH-related protein-but not vitamin D/calcitriol, calcitonin or sex steroids. In the days to weeks after birth, intestinal calcium absorption becomes an active process, which necessitates that the infant depends upon vitamin D/calcitriol. However, even this postnatal function of calcitriol can be bypassed by increasing the calcium content of the diet or by administering calcium infusions.

Choice of lumbar spine bone density reference database for fracture prediction in men and women: a population-based analysis.

The diagnosis of osteoporosis in men is controversial, although most studies demonstrate similar fracture rates for men and women with the same level of hip bone mineral density (BMD). Whether this applies to the lumbar spine is currently uncertain and has important implications with respect to choice of reference population for T-score calculation and osteoporosis diagnosis. This question was specifically addressed in the population-based Canadian Multicentre Osteoporosis Study cohort of 4745 women and 1887 men ages 50+ yr at the time of baseline lumbar spine dual energy x-ray absorptiometry. In up to 10 yr of observation, incident clinical major osteoporotic fractures occurred in 110 men (5.8%) vs 543 women (11.4%) (p < 0.001). Mean lumbar spine BMD in men was greater than in women, both among those with and those without incident major osteoporotic fracture (p < 0.001). Men were at slightly lower risk for incident major osteoporotic fracture than women for an equivalent lumbar spine BMD (age- and BMD-adjusted rate ratio 0.75, 95% confidence interval 0.60-0.93, p = 0.008) with similar findings after adjustment for the World Health Organization fracture risk assessment clinical risk factors or competing mortality. No significant sex difference in the BMD relationship was seen for vertebral fractures (clinical or radiographic) or for all fractures. In summary, this large population-based longitudinal cohort study found similar or lower fracture risk for men vs women after adjustment for absolute lumbar spine BMD and additional covariates. The least complicated model for describing fracture risk is therefore to use the same reference lumbar spine data for generating T-scores in men and women.

Complex clinical encounter series: osteoporosis presenting during pregnancy and lactation: wait and reassess.

Two months after her first pregnancy, a 35-yr-old exclusively breastfeeding woman bent to move her baby in the car seat and experienced sudden, severe pain from 5 spontaneous vertebral compression fractures. Genomic screen was negative but she had mild ankylosing spondylitis previously well controlled on etanercept. She was vegetarian with a high phytate intake. A lactation consultant had advised her to pump and discard milk between feeds, leading her to believe she produced twice as much milk as her baby ingested. She presented with a LS Z score of -3.6 and a TH Z score of -1.6. After 6 mo postweaning, she was treated with teriparatide (14 mo intermittently over 18 mo) and ultimately achieved a 50% increase in LS bone density and an 8% increase in TH bone density. Her fragility is explained by normal lactational bone loss amplified by excessive milk production and phytate-induced impairment of intestinal calcium absorption, ankylosing spondylitis, and the bend-and-lift maneuver. The marked increase in bone density resulted from the combined effects of spontaneous recovery and pharmacotherapy. Spontaneous recovery of bone mass and strength should occur during 12 mo after weaning in all women, including those who have fractured.

Capabilities of GPT-4o and Gemini 1.5 Pro in Gram stain and bacterial shape identification.

Aim: Assessing the visual accuracy of two large language models (LLMs) in microbial classification. Materials & methods: GPT-4o and Gemini 1.5 Pro were evaluated in distinguishing Gram-positive from Gram-negative bacteria and classifying them as cocci or bacilli using 80 Gram stain images from a labeled database. Results: GPT-4o achieved 100% accuracy in identifying simultaneously Gram stain and shape for Clostridium perfringens, Pseudomonas aeruginosa and Staphylococcus aureus. Gemini 1.5 Pro showed more variability for similar bacteria (45, 100 and 95%, respectively). Both LLMs failed to identify both Gram stain and bacterial shape for Neisseria gonorrhoeae. Cumulative accuracy plots indicated that GPT-4o consistently performed equally or better in every identification, except for Neisseria gonorrhoeae's shape. Conclusion: These results suggest that these LLMs in their unprimed state are not ready to be implemented in clinical practice and highlight the need for more research with larger datasets to improve LLMs' effectiveness in clinical microbiology.

This study looked at how well large language models (LLMs) could identify different types of bacteria using images, without having any specific training in this area beforehand.We tested two LLMs with image analysis capabilities, GPT-4o and Gemini 1.5 Pro. These models were asked to determine whether bacteria were Gram-positive or Gram-negative and whether they were round (cocci) or rod-shaped (bacilli). We used 80 images of four stained bacteria from a labeled database as a reference for this test.GPT-4o was more accurate in identifying both the Gram stain and shape of the bacteria compared with Gemini 1.5 Pro. GPT-4o had excellent accuracy in correctly classifying the Gram stain and bacterial shape of Clostridium perfringens, Pseudomonas aeruginosa and Staphylococcus aureus. Gemini 1.5 Pro had mixed results for these bacteria. However, both models struggled with Neisseria gonorrhoeae, failing to correctly identify its Gram stain and shape.The study shows that while these LLMs have potential, they are not ready to be implemented in clinical practice. More research and larger datasets are needed to improve their accuracy in clinical microbiology.