The effects of resistive exercise with low intensity-high frequency on essential mild hypertension in men

高血圧症は心筋梗塞, 脳卒中, 動脈硬化の独立した危険因子になっている。日本人30歳以上の成人男子の約48%が軽症を含めた高血圧症とされている。高血圧関連疾患や死亡の予防として軽症高血圧症時の血圧コントロールは重要な関心点である。薬物による高血圧治療は著しい効果をあげているが, 好ましくない副作用の発現も見逃せない。薬物療法に対して運動療法が近年広く処方されるようになってきた。これまでに多くの研究が有酸素運動の降圧効果を報告しているが, レジスタンス運動による降圧効果については異なる知見が出されている。そこで本研究においては, 有酸素運動の様式に似た低強度-高頻度レジスタンス運動を用いて中年軽症高血圧男子に対する降圧効果を検索した。方法。42歳-56歳 (平均48.3) の男子10名が被検者として参加し, 内5名がレジスタンス運動群 (RE) に他の5名がウオーキング群 (AE) に区分された。RE群は10種目のウエイト運動を最大筋力の40-50%強度, 20-25レペテイションで2-3セット, 週3回の形で12週間行った。一方のAE群は同様に予測最大心拍数の60-75%強度の30分速歩を週3回, 12週間行った。結果。安静時血圧においてRE群はAE群より程度は低いものの有意な (P値2.3ml/kg/min=6.9%) と身体組成の改善 (体脂肪1.5kg=8.8%減) が見られ, その改善率はAE群に比べて小さいがいずれも有意であった (AE群 : 6ml/kg/min=17%, 3.1kg=18.9%)。また, 体重もしくは体脂肪の減少量と降圧値との間には有意差が得られなかったが相関傾向が見られた。しかし, AE群と異なり, RE群では血清総コレステロール, 高比重リポ蛋白コレステロール, 低比重リポ蛋白コレステロール, トリグリセライド (中性脂肪) の血清脂質・リポ蛋白濃度の有意な改善は見られなかった。結語。これまで血圧や身体組成もしくは有酸素性体力の改善, 向上に対するレジスタンス運動の効果については意見の一致をみていない。考えられる要因の一つに運動の処方の違いが挙げられる。血圧や身体組成の改善に対しては低強度・高頻度による運動量負荷 (Volume loading) の処方が好ましく, 高強度による過重負荷 (Over-weight loading) は至適処方とは言えないであろう。今回の研究においてレジスタンス運動による血清脂質の有意な改善が見られなかったのは総運動量が十分な刺激とならなかったものと考えられる。本研究は低強度高頻度のレジスタンス運動の習慣化が軽症高血圧患者の健康改善に効果的であることを示唆するものである。Five sedentary middle-aged men with mild hypertension were studied to determine the effects of a low-to moderate-intensity resistive exercise program (RE group) on resting systolic and diastolic blood pressures. Another group of five mild hypertensive men was also examined to determine the effects of a moderate aerobic exercise program (AE group) on the resting blood pressures. Besides blood pressures, effects of respective training programs were studied on aerobic capacity, muscle strengths, and serum lipid and lipoprotein concentrations. Resistive exercise consisted of 10 stations of weight training machines for 12 weeks. Workloads were set at 40-50% maximum and the subjects performed 10 repetitions for each station with 2-3 sets, 3 times per week. The subjects in the aerobic exercise group performed 30-min brisk waking or jogging with intensities of 60-75% their predicted maximum heart rates. The following changes occurred in the resistive exercise group : (1) resting systolic blood pressure dropped significantly (from 150 to 143mm Hg) after training and diastolic blood pressure dropped significantly (from 91 to 88mm Hg) after training ; (2) VO_ significantly increased 2.3 ml/kg/min or 6.9% (from 33.3 to 35.6 ml/kg/min) after training ; (3) increases of muscle strengths were profound, 17.9% and 23% in lower and upper body strengths, respectively ; (4) body weight and body fat decreased 2.6% (P) as well as body composition. Serum lipid lipoproteins included total cholesterol (TC), high-density cholesterol (HDL-C), low-density lipoprotein cholesterol (LDL-C), and triglycerides (TG). Significant (P<0.01) increase was noted for HDL-C while significant decreases were seen in TC, LDL-C, and TG

Circadian clock does not play an essential role in daylength measurement for growth-phase transition in Marchantia polymorpha

Daylength is perceived as a seasonal cue to induce growth-phase transition at a proper time of a year. The core of the mechanism of daylength measurement in angiosperms lies in the circadian clock-controlled expression of regulators of growth-phase transition. However, the roles of the circadian clock in daylength measurement in basal land plants remain largely unknown. In this study, we investigated the contribution of circadian clock to daylength measurement in a basal land plant, the liverwort Marchantia polymorpha. In M. polymorpha, transition from vegetative to reproductive phase under long-day conditions results in differentiation of sexual branches called gametangiophores which harbor gametangia. First, we showed that a widely used wild-type accession Takaragaike-1 is an obligate long-day plant with a critical daylength of about 10 hours and requires multiple long days. Then, we compared the timing of gametangiophore formation between wild type and circadian clock mutants in long-day and short-day conditions. Mutations in two clock genes, MpTIMING OF CAB EXPRESSION 1 and MpPSEUDO-RESPONSE REGULATOR, had no significant effects on the timing of gametangiophore formation. In addition, when M. polymorpha plants were treated with a chemical which lengthens circadian period, there was no significant effect on the timing of gametangiophore formation, either. We next observed the timing of gametangiophore formation under various non-24-h light/dark cycles to examine the effect of phase alteration in circadian rhythms. The results suggest that daylength measurement in M. polymorpha is based on the relative amount of light and darkness within a cycle rather than the intrinsic rhythms generated by circadian clock. Our findings suggest that M. polymorpha has a daylength measurement system which is different from that of angiosperms centered on the circadian clock function

Mangrove plantation over a limestone reef - good for the ecology?

There have been efforts to restore degraded tropical and subtropical mangrove forests. While there have been many failures, there have been some successes but these were seldom evaluated to test to what level the created mangrove wetlands reproduce the characteristics of the natural ecosystem and thus what ecosystem services they can deliver. We provide such a detailed assessment for the case of Olango and Banacon Islands in the Philippines where the forest was created over a limestone reef where mangroves did not exist in one island but they covered most of the other island before deforestation in the 1940s and 1950s. The created forest appears to have reached a steady state after 60 years. As is typical of mangrove rehabilitation efforts worldwide, planting was limited to a single Rhizophora species. While a forest has been created, it does not mimic a natural forest. There is a large difference between the natural and planted forests in terms of forest structure and species diversity, and tree density. The high density of planted trees excludes importing other species from nearby natural forests; therefore the planted forest remains mono-specific even after several decades and shows no sign of mimicking the characteristics of a natural forest. The planted forests provided mangrove propagules that invaded nearby natural forests. The planted forest has also changed the substratum from sandy to muddy. The outline of the crown of the planted forest has become smooth and horizontal, contrary to that of a natural forest, and this changes the local landscape. Thus we recommend that future mangrove restoration schemes should modify their methodology in order to plant several species, maintain sufficient space between trees for growth, include the naturally dominant species, and create tidal creeks, in order to reproduce in the rehabilitated areas some of the key ecosystem characteristics of natural mangrove forests

Serrated polyps–a concealed but prevalent precursor of colorectal cancer

Serrated polyps have long been considered to lack malignant potential but accumulating data suggest that these lesions may cause up to one-third of all sporadic colorectal cancer. Serrated polyps are classified into three subtypes, including sessile serrated adenomas/polyps (SSA/Ps), traditional serrated adenomas (TSAs), and hyperplastic polyps (HPs). SSA/P and TSA harbour malignant potential but TSA represents only 1–2%, wheras SSA/P constitute up to 20% of all serrated lesions. HPs are most common (80%) of all serrated polyps but are considered to have a low potential of developing colorectal cancer. Due to their subtle appearence, detection and removal of serrated polyps pose a major challenge to endoscopists. Considering that precancerous serrated polyps are predominately located in the right colon could explain why interval cancers most frequently appear in the proximal colon and why colonoscopy is less protective against colon cancer in the proximal compared to the distal colon. Despite the significant impact on colorectal cancer incidence, the aetiology, incidence, prevalence, and natural history of serrated polyps is incompletely known. To effectively detect, remove, and follow-up serrated polyps, endoscopists and pathologists should be well-informed about serrated polyps. This review highlights colorectal serrated polyps in terms of biology, types, diagnosis, therapy, and follow-up

Potential role of a novel endoscopic retrieval bag for large colorectal resected specimen: a proof-of-concept study

Endoscopic submucosal dissection enables en bloc resection of large superficial colorectal neoplasms. However, it is sometimes challenging to retrieve a large resected specimen via the anus without sample fragmentation. A novel “bag-type” retrieval device has been developed to accomplish complete isolation and non-destructive delivery of oversized specimens. This single-center retrospective study was performed to demonstrate the efficacy of this device for large colorectal resected specimens. Among 17 patients, we identified 18 superficial colorectal lesions for which the use of a novel retrieval device (Endo Carry Large Type) was indicated at specimen delivery at a referral cancer institute from March 2021 to July 2022. The median (interquartile range) tumor size was 62.5 (52.0–79.5) mm. Retrieval of 17 (94%) of 18 resected specimens was performed using the Endo Carry Large Type, and 16 (89%) were successfully retrieved without sample fragmentation. The median (interquartile range) retrieval time was 4 (4–8) minutes, and no apparent adverse events were observed. The novel Endo Carry Large Type device can accomplish colorectal specimen retrieval safely and quickly without specimen damage and therefore may contribute to accurate pathological diagnosis