Study of anomalies in the circle of Willis using magnetic resonance angiography in north eastern India

IntroductionThe circle of Willis is a large arterial anastomotic ring present at the basal cistern of the brain, uniting the internal carotid and the vertebrobasilar system. Branches from this arterial ring are distributed to supply the brain. In the year 1664, Sir Thomas Willis was the first to describe the importance of the circle in maintaining collateral flow. It was observed that there is very little mixing of blood between the collateral branches of the circle. These collaterals may however open up during occlusive episodes of the proximal feeding vessels. The anatomy of the circle is known to vary considerably and functionally a complete circle is a rare finding. This type of incomplete or variant forms off the circle may diminish its role as a collateral route.MethodsThe morphological pattern of circle of Willis of 70 healthy individuals from northeast India was studied retrospectively using Time of Flight-Magnetic resonance angiography (TOF-MRA).ResultsOnly 17 (24.28%) MRA's presented with a complete (classic) circle of Willis. Most common variant observed in our study was unilateral hypoplastic posterior communicating artery (20%). Most common variant observed in the anterior circulation was unilateral hypoplastic A1 segment of anterior cerebral artery (11.42%).DiscussionMost of the variant forms observed were comparable with earlier established findings. This variability (rare patterns) can be distinguished from an anomalous architecture if correlated phylogenically and embryologically.     

Some observations on the cerebral arterial circles of mink (Mustela vison)

With the exception of a brief allusion to an unidentified species of Mustela with regard to cerebral vascular studies by de Vriese ('05), major information concerning the circle of Willis in mink was nonexistent until the present investigation. Brains of mink in which the cerebral arterial circles were injected with latex and subsequently hardened in formalin, revealed the primary cerebral arterial anastomosis to be ring-like in form; all of the component vessels were patent and well formed, none was attenuated or string-like. Some of the more prominent findings included: (1) a predominance of asymmetric divergence of the posterior communicating arteries separating from the bifurcating basilar artery; (2) the presence of a posterior intercommunicating artery in all of the specimens; (3) the occasional doubling of the superior cerebellar and the posterior cerebral arteries; (4) deeply placed internal cerebral loops forming secondary arterial anastomoses between some penetrating vessels in the caudal region of the circle; other loops interconnected other penetrating vessels in the rostral region of the circle; (5) blood channels forming an intercarotid anastomosis traversed the pia mater; (6) the presence of a penetrating artery adjunctive to the recurrent artery of Heubner; (7) anastomoses between the internal and the external ophthalmic arteries, and between the internal and the external olfactory arteries forming collateral channels of communication between the intracranial and the extracranial circulations; (8) the occasional presence of an anterior communicating artery supplementing the commonly occurring azygos anterior cerebral artery which continued as a single vessel throughout its extent; (9) unjoined anterior cerebral arteries in one animal which was exceptional.     

Decrease of plasma somatostatin-like immunoreactivity and increase of gastrin and insulin levels in peripheral venous blood of conscious dogs following infusions of pentagastrin. The possible role of vagal “gastrinergic” fibres as inhibitors of gastrointestinal somatostatin release

Somatostatin has been shown to exert inhibitory actions on gastric acid secretion, gastrointestinal motility and on the release of gastrointestinal and pancreatic hormones. Furthermore, somatostatin is produced and stored in endocrine cells in the corporeal and antral parts of the stomach and in the pancreas, indicating that endogenous somatostatin might take part in the control of gastrointestinal and pancreatic functions. (For a review on the subjects see Efendic, Luft & Uvnäs-Wallensten 1982.)     

Stomach serosal arteries distinguish gastric regions of the rat

Because the stomach in situ has few distinctive surface features and changes shape dramatically with food intake, we have used micro-CT imaging combined with two distinct contrast agents to (1) characterize the pattern of arteries, potential landmarks, on the stomach wall and (2) evaluate how meal-related shape changes affect the size of the different regions. Images generated with a contrast agent injected directly into the heart during perfusion enabled a thorough look at the organizational features of the stomach angioarchitecture. The stomach receives its blood supply primarily from two pairs of vessels, the gastric and gastroepiploic arteries. Each of the three regions of the stomach is delineated by a distinctive combination of arterial fields: the corpus, consistent with its dynamic secretory activity and extensive mucosa, is supplied by extensive arterial trees formed by the left and right gastric arteries, travelling, respectively, on the ventral and dorsal stomach surfaces. These major arteries course circularly from the lesser towards the greater curvature, distally along both left (or ventral) and right (or dorsal) walls of the corpus, and branch rostrally to supply the region. The muscular antrum is characterized by smaller arterial branches arising primarily from the right gastroepiploic artery that follows the distal greater curvature and secondarily from small, distally directed arteries supplied by the large vessels of the left and right gastric arteries. The forestomach, essentially devoid of mucosal tissue and separated from the corpus by the limiting ridge, is vascularized predominantly by a network of small arteries issued from the left gastroepiploic artery coursing around the proximal greater curvature, as well as from higher order and smaller branches issued by the gastric and celiac arteries. These distinctive arterial fields appear to distinguish the major gastric regions, irrespective of the degree of fill of the stomach. Volume assessments of stomach compartments were made from images of iodine-stained stomachs. By varying the delay time between eating and perfusion, we were able to probe the emptying behavior of the stomach and demonstrate that the regions of the stomach empty at different rates, thus changing the relative dimensions of the organ regions. Notably, and despite these shape changes, the gastric arteries appear to form a regular, particularly recognizable, and lateralized pattern corresponding to the corpus that should be of use in guiding surgical and experimental interventions.     

Internal Ophthalmic Arteries Within the Brain‐Base Arterial System in Guinea Pig

In situ vascular specimens of the arterial circle were collected from 15 adult guinea pigs, both male and female. After specimen preparation, the vessels were filled with synthetic latex and subjected to analysis. Similar as in the case of other rodents, vertebral arteries were merged into basilar artery, further dividing into two short terminal branches. Distally, the terminal branches extend into caudal cerebral arteries. Rostral part of the arterial circle of brain is supplied with blood from maxillary arteries via external and internal ophthalmic arteries connected by a short anastomosis. This type of vascularity may probably be considered a functional analogy to the internal carotid arteries observed in other species. Rostral and caudal parts of the arterial circle of brain are connected by exceptionally long caudal communicating arteries. In author's opinion, the disputable contribution of internal carotid artery and the exceptional contribution of internal ophthalmic arteries in the cerebral blood supply in guinea pigs as compared to other rodents, warrants further research on the subject. Anat Rec, 301:887–891, 2018. © 2017 Wiley Periodicals, Inc.     

Atypical coeliomesenteric anastomosis: The presence of an anomalous fourth coeliac trunk branch

The presence of more than three coeliac trunk branches is a commonly encountered variant. Literature occasionally describes cases of middle or left colic arteries originating from the celiac trunks or its branches; however, the presence of an anomalous arterial connection between the celiac trunk and both the superior and inferior mesenteric arteries (SMA and IMA, respectively) has yet to be reported. Routine abdominal dissection of a male Caucasian cadaver, revealed the presence of an anomalous fourth arterial branch on the 4‐cm long coeliac trunk. The course of this artery was traced, and it terminated by anastomosing with the marginal artery of the mesenteric circulation. The distal termination point of this anomalous fourth coeliac branch was the marginal artery, 5 cm medial of the splenic flexure, anastomosing almost perpendicularly. The diameter of this anomalous artery was comparable with the left gastric artery at their origins. The artery coursed inferiorlaterally toward the splenic flexure, passing immediately posterior to both the pancreas and the splenic vein. The anastomosis point of this artery, near Griffith's Point, is normally considered a watershed region with dual arterial supply from both the SMA and IMA, allowing collateral circulation. This region has a relatively higher susceptibility to irreversible damage in ischemic diseases because of lower perfusion, thus, the anastomosis of atypical coeliac branches represents a rare case for consideration. Awareness of the possibility of embryological variants will minimize the risk of complications in surgical or clinical procedures, and exploration of rare variants will benefit the understanding of vascular embryology. Clin. Anat., 2010. © 2010 Wiley‐Liss, Inc.     

Morphometry and Variability of the Brain Arterial Circle in Chinchilla (Chinchilla laniger,Molina)

Arterial circles of brains from 70 adult chinchillas were filled with synthetic latex. The arterial circle of the brain is formed as the result of vertebral arteries being merged into the basilar artery. Caudally, both vertebral arteries gave rise to the ventral spinal artery. The ventral spinal artery splits into tiny cerebellar vessels, the pontine and cochlear branches. Distally, the basilar artery ramified into two terminal branches that formed the arterial circle of brain, rostrally open in most cases (75%). The observed variability of the arterial circle of brain of chinchillas pertained to all elements of that circle. The greatest variability within the vessels of the circle of Willis in chinchillas was observed in 22 cases (31.4%) of internal ophthalmic arteries. In chinchillas, a trend toward slight variability within the arteries comprising the arterial circle of the brain was observed in 44 animals. This accounted for 62.8% of all cases. Only in three cases was the arterial circle of brain clearly symmetrical. At the same time, 23 animals (32.8%) revealed features of significant vascular variability within the brain base region. These consisted of disturbed geometry of the entire arterial circle, different levels of ramifications into individual arteries, as well as the number and diameter of arteries. No internal carotid arteries were observed in chinchillas apart from one atypical case in which the carotid artery extended unilaterally into the basilar artery. These investigations indicate on the significant variability of arterial circle in rodents. Anat Rec, 300:1472–1480, 2017. © 2017 Wiley Periodicals, Inc.     

张力吻合对动脉顺应性影响的实验研究

目的 探讨动脉张力吻合后其顺应性的变化。方法 在体测定犬股动脉非吻合、正常吻合及张力吻合后不同时相点吻合口段的压力与直径相应的数据，推算动脉非吻合、正常及张力吻合后的顺应性，确定动脉顺应性与平均血压的关系。结果 在各时相点，吻合组动脉的顺应性低于非吻合组，张力吻合组动脉的顺应性低于正常吻合组，术后14d降低最显著。结论 动脉张力吻合术后近期吻合口段的可扩张能力较正常吻合动脉及正常动脉有明显减弱，张力吻合对吻合口段动脉的功能有较大影响。     

Leukotrienes do not contribute to the pathogenesis of indomethacin-induced ulceration of the gastric antrum in the re-fed rat

The potential involvement of leukotrienes in the pathogenesis of indomethacin-induced ulceration of the rat gastric antrum has been studied. Pretreatment with the leukotriene biosynthesis inhibitor, MK886 (30 mg/kg p.o.), inhibited the increases in blood and antral leukotriene B₄ releaseex vivo associated with the evolution of antral ulceration. Despite this, however, there was no significant reduction in either the area of antral ulceration, or in the associated blood neutrophilia and neutrophil infiltration into the gastric antrum. Similarly, pretreatment with the leukotriene B₄ antagonist, SC41930 (50 mg/kg p.o.) or the peptidyl leukotriene antagonist ICI198,615 (50 mg/kg p.o.) did not inhibit the area of antral ulceration induced by indomethacin.Thus, in contrast to published reports studying fundic ulceration, our results suggest that leukotrienes do not play a major role either in the pathogenesis of indomethacin-induced ulceration of the rat gastric antrum or neutrophil infiltration into the damaged antrum.     

A rare variation of the coeliac trunk.

The hepatic, splenic and Left gastric arteries are considered as the "main classic branches" of the coeliac trunk. During the routine dissections in the laboratory of the Anatomy Department in a 62-year-old male cadaver, a rare variation, a coeliacomesenteric trunk was observed. This trunk gave rise to the left gastric, the common hepatic, the splenic, the left gastro-epiploic, the right and left inferior phrenic arteries. The developmental and clinical significance of this anomalous vessel is discussed.     

Aberrant left gastric vein directly draining into the liver

An aberrant left gastric vein found in dissection is reported here. The right gastric vein did not exist and only the left gastric vein originating from the lesser curvature of the stomach was present. It directly entered the liver without typically joining the trunk of the portal vein. After giving off a small branch to the liver parenchyma, the left gastric vein merged into the left branch of the portal vein. This aberrant left gastric vein may correspond to the phylogenetic and ontogenetic "left portal vein." The aberrant left gastric vein is considered to play an important role as a portal collateral pathway of the portal system, which is critical not only in anatomy but also in clinical diagnosis.     

动脉张力吻合后的顺应性变化

通过在体测定狗股动脉非吻合、正常吻合及张力吻合后不同时相点吻合口段的压力与直径相应的数据 ,计算出动脉非吻合、正常及张力吻合后的顺应性 ,顺应性与平均血压曲线用幂函数 C=bem Pa进行拟合 ,建立顺应性与平均血压的关系。结果表明 :在各时相点 ,吻合组的顺应性低于非吻合组 ,张力吻合组吻合口段动脉的顺应性低于正常吻合组 ,术后 14 d降低最显著。反映出动脉张力吻合术后近期吻合口段的可扩张能力较正常吻合动脉及正常动脉有明显减弱。张力吻合对吻合口段动脉的功能有较大影响     

Simultaneous aberrant left and right gastric veins draining directly into the liver.

Aberrant gastric veins draining directly into the liver are rare variations of the portal vein system. We report on an autopsy in which both right and left gastric veins drained directly into the liver without joining the portal vein. Although the left gastric artery adopted a standard disposition, the left gastric vein was indeed found to ascend from the lesser curvature through the upper part of the lesser omentum. After receiving branches from the gastroesophageal junction, it directly entered the left part of the porta hepatis. The right gastric vein ascended from the lesser gastric curvature along and in front of the right aspect of the common bile duct without ending in the portal vein. It crossed in front of the common hepatic duct and directly entered the porta hepatis. Careful dissection within the liver parenchyma showed that both gastric veins ended in the intra-hepatic part of the left branch of the portal vein. Although aberrant gastric veins are known variations of the portal vein system, the conjunction of both right and left gastric vein has never been reported. It highlights the possibility that the venous drainage of the gastric lesser curvature may be totally independent of the main portal vein.     

The effects of general anaesthesia on antroduodenal motility, gastric pH and gastric emptying in man

This survey was based on five recently published papers. The aims of the studies were to to investigate the effect of general anaesthesia on antroduodenal motility, gastric pH and gastric emptying. Antroduodenal motility was measured by manometry, gastric pH by a stomach microelectrode and gastric emptying rate using paracetamol absorption as an index. Two studies deal with antroduodenal motility during basal conditions and after administration of paracetamol and diazepam in 11 healthy volunteers. Three studies deal with the effects of 4 different methods of general anaesthesia on antroduodenal motility, gastric pH and gastric emptying rate in 43 patients undergoing orthopedic or plastic surgery not involving the abdomen having four different methods of general anaesthesia. In the healthy volunteers a close connection between antral activity and gastric emptying rate was found. Paracetamol had no effects on gastric pH. The changes in motility (a shortening of phase III and a decline in the incidence of antral phase III activity) were minor and ascribed to diurnal variations and by a possible stimulation of antral activity by the positioning of the manometric tube. It was found that no paracetamol was absorbed in the quiescent phase I, irrespective of its duration, and that the absorption rate of paracetamol correlated with the duration of phase II and the occurrence of antral activity during phases II and III. The effects of premedication with diazepam on antroduodenal motility, gastric pH and gastric emptying rate was investigated in the same healthy volunteers prior to the patient studies. Also in this study a correlation between antral activity and gastric emptying rate was found. Furthermore, it was observed that some volunteers had fast gastric emptying rate, indicated by fast absorption of paracetamol, the first study day and slow the second. It seemed that any intra- or interindividual variation in gastric emptying rate arises from individual variations in antroduodenal motility. Diazepam tended to increase gastric emptying rate by enhancing the amplitudes of antral contractions and the motility index during phase II and pH of the gastric juice increased. Gastroduodenal motility was found to be normal in patients awaiting elective orthopedic or plastic surgery when premedicated with diazepam. pH of the gastric contents was not different from the findings in volunteers after administration of diazepam. All methods of general anaesthesia reduced the duration of the interdigestive motility complex, mainly by a reduction of phase II. General anaesthesia with halothane and enflurane depressed antral motility.(ABSTRACT TRUNCATED AT 400 WORDS)     

动脉正常吻接和张力吻接后顺应性对比研究

通过在体测定狗股动脉正常吻接和张力吻接后不同时相点吻合口段的压力与直接相应的数据,从而得出动脉在正常及张力吻接后的顺应性,以及顺应性与平均血压的关系。结果表明：在各时相点,张力吻接组吻合口段动脉的顺应性均低于正常吻接组,反映出动脉张力吻接合吻合口段的可扩张能力较正常吻接动脉有明显减弱,术后14天减弱最显著,张力吻合对吻合口段动脉的功能有较大影响。     

利用微血管铸型技术研究肝外胆管动脉的分布特征

目的　统计分析肝外胆管的血供来源和分布以及在十二指肠上段胆管的吻合动脉链之间的多环形血管网,为胆管外科手术提供临床解剖学理论依据。 方法　以丙烯酸树脂为动脉填充剂灌注6例肝外胆管动脉制备铸型标本,使用photoshop测量法测量微小血管内径,观测和分析肝外胆管的血供来源和分布情况。 结果　肝固有动脉左、右支在肝总管上方存在弓型交通支,十二指肠上段胆管左右边缘的吻合动脉链间有丰富的横向动脉,吻合动脉链的供血约53%来自下方,来自上方的约占46%,1%来自中段肝固有动脉。通过对每条横向动脉中部的内径和两侧起始部的内径测量,发现肝总管中段和上段的横向动脉较粗,中部的平均内径分别为（0.26±0.02）mm和（0.24±0.04）mm,与两侧的内径比也比较大,上段比值最大,为1.09,中段其次,为1,下段中部的平均内径为（0.14±0.03）mm;与两侧的内径比值为0.74。 结论　肝外胆管上、下方的血供来源比例相对均衡;肝外胆管手术应尽可能于动脉吻合相对较少的胆总管十二指肠上段和血管相对较细小肝总管下部做纵行小切口,以降低肝外胆管血供的损伤;肝总管段的血供丰富,支持现行原位肝移植离断部位在胆囊管汇合处上方的主张。     

A reinterpretation of the events in gastric carcinogenesis

It is proposed here that the initial events in gastric carcinogenesis occur at the junction of the oxyntic and antral mucosae. Intestinal metaplasia represents an adaptive counter-response to early neoplastic change at this site. Chronic gastric ulceration may arise due to the elimination of overtly dedifferentiated cells at a later stage in the evolution of the neoplastic process. Intestinal type gastric carcinoma possibly represents breakthrough past these mechanisms.     

Heterotopic ossification induced by hypoxia in a retrosternal gastric tube following transhiatal oesophagectomy.

A 71 year old man underwent retrosternal gastric tube reconstruction following transhiatal oesophagectomy for squamous cell carcinoma. On the second post-operative day, the patient developed a cardiac arythmia with secondary hypotension followed by hypoxaemia necessitating artificial ventilation. Two weeks after surgery, endoscopy revealed massive necrosis of the proximal segment of the gastric tube extending from the anastomosis in the neck to the watershed area. Three weeks later, the patient died and a necropsy was performed. Macroscopic evaluation of the gastric tube revealed a sharply demarcated and fully ossificated proximal segment. Heterotopic ossification was present on histological examination. This condition has only been described in conjunction with primary or metastatic gastric adenocarcinoma. The location of the ossification and the presence of temporary systemic hypoxia suggest that the latter was the main factor responsible for the ossificative response.