Brainstem auditory evoked potential interwave intervals are prolonged in vitamin B-6-deficient cats

Factors influencing vitamin B6 status in domestic cats: age, disease, and body condition score

Limited studies are available on vitamin B6 status in domestic cats. To this end, we evaluated glutamate-oxaloacetate transaminase (GOT) activity in hemolysates with and without pyridoxal 5'-phosphate addition in two feline populations: a cohort of 60 healthy, domestic (sexually intact and specific pathogen-free) cats maintained under strictly controlled conditions with appropriate diets housed at the Feline Nutrition and Pet Care Center, and a cohort of 57 cats randomly selected between December 2022 to January 2023 that visited the Veterinary Medicine Teaching Hospital to seek care under different circumstances. The GOT activity expressed as the ratio with and without pyridoxal 5'-phosphate addition (primary activation ratio; PAR) decreased significantly with age in the healthy cohort. The PAR values normalized to age established a cut-off for vitamin B6 deficiency in both cohorts, identifying 17 of 101 animals as vitamin B6 deficient. Using machine learning, a partition-based model (decision tree) was built to identify the most important factors that predicted vitamin B6 deficiency while using the resulting tree to make predictions for new observations. This analysis, performed with all 101 cats, revealed that the diagnosis of an infectious, chronic or acute condition (0.55) was the main contributor, followed by age (0.26), and body condition score (optimal-overweight; 0.19). Thus, our study supports that vitamin B6 supplementation may be indicated in junior to adult animals diagnosed with an infectious, chronic, or acute conditions or healthy cats with body weight ranging from optimal to overweight. In older cats, even if healthy, underweight to optimal cats appear to be at risk of vitamin B6 deficiency.

Age-related hearing loss, vitamin B12, and folate in the elderly

OBJECTIVE

Determine the correlation between the hearing threshold and the serum levels of vitamin B12 (cobalamin) and folic acid among elderly subjects (> 60 years) with age-related hearing loss (ARHL).

STUDY DESIGN

Cross-sectional.

SETTING

Community.

SUBJECTS AND METHODS

Subjects included elderly who were found apparently healthy following repeated examination by physicians. The pure tone average (PTA) for the speech and high frequencies, and the serum folate and cobalamin were determined and the correlation found.

RESULTS

The mean ± SD values of serum folate among the subjects with normal PTA in the speech frequencies (0-30 dB) was 412.3 nmol/L ± 17.6 nmol/L, while among those with hearing loss (HL), it was 279.1 nmol/L ± 17.2 nmol/L (P = 0.01). In the high frequencies, the mean ± SD values among the subjects with normal PTA was 426.3 nmol/L ± 17.6 nmol/L, while among those with HL, it was 279.14 nmol/L ± 171.2 nmol/L. The serum cobalamin among the subjects with normal PTA within the speech frequencies was 49.7 pmol/L ± 9.4 pmol/L, while among those with speech-frequency HL, it was 42.6 pmol/L ± 10.2 pmol/L. However, for high frequencies, the mean ± SD values among the subjects with normal PTA was 47.4 pmol/L ± 7.3 pmol/L, while among those with HL, it was 41.3 pmol/L ± 9.2 pmol/L. Spearman's correlation revealed that low folate (correlation coefficient = -0.27, P = 0.01) and cyanocobalamin (correlation coefficient = -0.35, P = 0.02) were significantly associated with increasing hearing threshold in the high frequencies. After adjusting for age, serum folate (correlation coefficient = -0.01, P = 0.01) was significant, while vitamin B12 (correlation coefficient = -0.01, P = 0.74) was not.

CONCLUSION

Serum folate was significantly lower among elderly with ARHL. Trials on nutritional supplementation may substantiate the role of serum folate in ARHL.

Vitamin B6 deficiency decreases the glucose utilization in cognitive brain structures of rats

The effects of vitamin B(6) deficiency on metabolic activities of brain structures were studied. Male Sprague-Dawley weanling rats received one of the following diets: (1) 7 mg pyridoxine HCl/kg (control group); (2) 0 mg pyridoxine HCl/kg (vitamin B(6)-deficient group); or (3) 7 mg pyridoxine HCl/kg with food intake restricted in quantity to that consumed by the deficient group (pair-fed control group). After 8 weeks of dietary treatment, rats in all three groups received an intravenous injection of 2-deoxy-[(14)C] glucose (100 microCi/kg). Vitamin B(6) status was evaluated by plasma pyridoxal 5'-phosphate concentrations. The vitamin B(6)-deficient group had significantly lower levels of plasma pyridoxal 5'-phosphate than did the control and pair-fed groups. The local cerebral glucose utilization rates in structures of the limbic system, basal ganglia, sensory motor system, and hypothalamic system were determined. The local cerebral glucose utilization rates in each of the four brain regions in the deficient animals were approximately 50% lower (P < 0.05) than in the control group. Results of the present study suggest that serious cognitive deficit may occur in vitamin B(6)-deficient animals.

Age-related hearing loss, vitamin B-12, and folate in elderly women

BACKGROUND

Hearing impairment is 1 of the 4 most prevalent chronic conditions in the elderly. However, the biological basis of age-related hearing loss is unknown.

OBJECTIVE

The objective was to test the hypothesis that age-related hearing loss may be associated with poor vitamin B-12 and folate status.

DESIGN

A thorough audiometric assessment was conducted in 55 healthy women aged 60-71 y. Hearing function was determined by the average of pure-tone air conduction thresholds at 0.5, 1, 2, and 4 kHz and was categorized into 2 groups for logistic regression analyses: normal hearing (<20 dB hearing level; n = 44) and impaired hearing (> or = 20 dB hearing level; n = 11).

RESULTS

Mean age was the same (65 y) for the normal hearing and impaired hearing groups. Pure-tone averages were inversely correlated with serum vitamin B-12 (r = -0.58, P = 0.0001) and red cell folate (r = -0.37, P = 0.01). Women with impaired hearing had 38% lower serum vitamin B-12 (236 compared with 380 pmol/L, respectively, P = 0.008) and 31% lower red cell folate (425 compared with 619 nmol/L, respectively, P = 0.02) than women with normal hearing. Among participants who did not take supplements containing vitamin B-12 or folate, women with impaired hearing had 48% lower serum vitamin B-12 (156 compared with 302 pmol/L, respectively, P = 0.0007) and 43% lower red cell folate (288 compared with 502 nmol/L, respectively, P = 0.001) than women with normal hearing.

CONCLUSION

Poor vitamin B-12 and folate status may be associated with age-related auditory dysfunction.

Impaired brainstem auditory evoked potentials in patients with cystic fibrosis

Brainstem auditory evoked potentials (BAEPs) were measured in 11 young patients with cystic fibrosis (CF). Though none had clinical evidence of neurological impairment, all had various abnormal components of brainstem auditory evoked potentials (BAEPs). Abnormal BAEPs may be attributed to nutritional deficiencies including deficiencies of vitamins E and B6. As patients with CF are often deficient in vitamin E despite daily supplementation and normal serum levels, the authors suggest that the abnormal BAEPs demonstrated in the present study may reflect prolonged intracellular vitamin E deficiency. This finding suggests that BAEP studies may be useful in the neurological evaluation of patients with CF.

A critical review of minimal vitamin B6 requirements for growth in various species with a proposed method of calculation

We conclude that vitamin B6 is efficiently conserved by the tissues and that the major dietary requirement is to meet physiological stresses such as growth, pregnancy, lactation, vigorous exercise, and/or disease. A reasonable approximation of the minimal requirement for growth in most species can be obtained by assuming 15 nmol vitamin B6 for each g gain in body weight. For birds and fish, which can achieve 1 g gain/g feed, the vitamin B6 content would need to be about 15 mumol (3 mg)/kg feed. Such an intake is achievable with a variety of natural diets and would also be adequate for most mammalian species, which have lower feed efficiencies. Although well-balanced natural diets are usually adequate, supplementation with 5-10 mumol (1-2 mg)/kg diet is inexpensive and would provide a safety factor to allow for variations in feed composition and physiological stresses such as pregnancy, disease, parasites, and so on. At this time, whether the metabolic changes associated with increases in vitamin B6 intake above the minimum confer long-term health benefits on the organisms is not clear. Excessive vitamin B6 intake can be toxic. Fish and prawn seem to be particularly sensitive to this toxicity. Additional work is needed to clarify the interactions between vitamin B6 requirements and protein intake.